ftp.cc.uoc.gr
rfc3525
This is a purely informative rendering of an RFC that includes verified errata. This rendering may not be used as a reference.

The following 'Verified' errata have been incorporated in this document: EID 256
Network Working Group                                          C. Groves
Request for Comments: 3525                                   M. Pantaleo
Obsoletes: 3015                                              LM Ericsson
Category: Standards Track                                    T. Anderson
                                                              Consultant
                                                               T. Taylor
                                                         Nortel Networks
                                                                 Editors
                                                               June 2003


                  Gateway Control Protocol Version 1

Status of this Memo

   This document specifies an Internet standards track protocol for the
   Internet community, and requests discussion and suggestions for
   improvements.  Please refer to the current edition of the "Internet
   Official Protocol Standards" (STD 1) for the standardization state
   and status of this protocol.  Distribution of this memo is unlimited.

Copyright Notice

   Copyright (C) The Internet Society (2003).  All Rights Reserved.

Abstract

   This document defines the protocol used between elements of a
   physically decomposed multimedia gateway, i.e., a Media Gateway and a
   Media Gateway Controller.  The protocol presented in this document
   meets the requirements for a media gateway control protocol as
   presented in RFC 2805.

   This document replaces RFC 3015.  It is the result of continued
   cooperation between the IETF Megaco Working Group and ITU-T Study
   Group 16.  It incorporates the original text of RFC 3015, modified by
   corrections and clarifications discussed on the Megaco
   E-mail list and incorporated into the Study Group 16 Implementor's
   Guide for Recommendation H.248.  The present version of this document
   underwent  ITU-T Last Call as Recommendation H.248 Amendment 1.
   Because of ITU-T renumbering, it was published by the ITU-T as
   Recommendation H.248.1 (03/2002), Gateway Control Protocol Version 1.

   Users of this specification are advised to consult the H.248 Sub-
   series Implementors' Guide at http://www.itu.int/itudoc/itu-
   t/com16/implgd for additional corrections and clarifications.

Conventions used in this document

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
   document are to be interpreted as described in RFC 2119 [RFC2119].

Table of Contents

   1 Scope.........................................................5
     1.1 Changes From RFC 3015.....................................5
     1.2 Differences From ITU-T Recommendation H.248.1 (03/2002)...5
   2 References....................................................6
     2.1 Normative references......................................6
     2.2 Informative references....................................9
   3 Definitions..................................................10
   4 Abbreviations................................................11
   5 Conventions..................................................12
   6 Connection model.............................................13
     6.1 Contexts.................................................16
     6.2 Terminations.............................................17
       6.2.1 Termination dynamics.................................21
       6.2.2 TerminationIDs.......................................21
       6.2.3 Packages.............................................22
       6.2.4 Termination properties and descriptors...............23
       6.2.5 Root Termination.....................................25
   7 Commands.....................................................26
     7.1 Descriptors..............................................27
       7.1.1 Specifying parameters................................27
       7.1.2 Modem descriptor.....................................28
       7.1.3 Multiplex descriptor.................................28
       7.1.4 Media descriptor.....................................29
       7.1.5 TerminationState descriptor..........................29
       7.1.6 Stream descriptor....................................30
       7.1.7 LocalControl descriptor..............................31
       7.1.8 Local and Remote descriptors.........................32
       7.1.9 Events descriptor....................................35
       7.1.10 EventBuffer descriptor..............................38
       7.1.11 Signals descriptor..................................38
       7.1.12 Audit descriptor....................................40
       7.1.13 ServiceChange descriptor............................41
       7.1.14 DigitMap descriptor.................................41
       7.1.15 Statistics descriptor...............................46
       7.1.16 Packages descriptor.................................47
       7.1.17 ObservedEvents descriptor...........................47
       7.1.18 Topology descriptor.................................47
       7.1.19 Error Descriptor....................................50
     7.2 Command Application Programming Interface................50
       7.2.1 Add..................................................51

       7.2.2 Modify...............................................52
       7.2.3 Subtract.............................................53
       7.2.4 Move.................................................55
       7.2.5 AuditValue...........................................56
       7.2.6 AuditCapabilities....................................59
       7.2.7 Notify...............................................60
       7.2.8 ServiceChange........................................61
       7.2.9 Manipulating and Auditing Context Attributes.........65
       7.2.10 Generic Command Syntax..............................66
     7.3 Command Error Codes......................................66
   8 Transactions.................................................66
     8.1 Common parameters........................................68
       8.1.1 Transaction Identifiers..............................68
       8.1.2 Context Identifiers..................................68
     8.2 Transaction Application Programming Interface............69
       8.2.1 TransactionRequest...................................69
       8.2.2 TransactionReply.....................................69
       8.2.3 TransactionPending...................................71
     8.3 Messages.................................................72
   9 Transport....................................................72
     9.1 Ordering of Commands.....................................73
     9.2 Protection against Restart Avalanche.....................74
   10 Security Considerations.....................................75
     10.1 Protection of Protocol Connections......................75
     10.2 Interim AH scheme.......................................76
     10.3 Protection of Media Connections.........................77
   11 MG-MGC Control Interface....................................78
     11.1 Multiple Virtual MGs....................................78
     11.2 Cold start..............................................79
     11.3 Negotiation of protocol version.........................79
     11.4 Failure of a MG.........................................80
     11.5 Failure of an MGC.......................................81
   12 Package definition..........................................82
     12.1 Guidelines for defining packages........................82
       12.1.1 Package.............................................83
       12.1.2 Properties..........................................84
       12.1.3 Events..............................................85
       12.1.4 Signals.............................................85
       12.1.5 Statistics..........................................86
       12.1.6 Procedures..........................................86
     12.2 Guidelines to defining Parameters to Events and Signals.86
     12.3 Lists...................................................87
     12.4 Identifiers.............................................87
     12.5 Package registration....................................88
   13 IANA Considerations.........................................88
     13.1 Packages................................................88
     13.2 Error codes.............................................89
     13.3 ServiceChange reasons...................................89

   ANNEX A  Binary encoding of the protocol.......................90
     A.1 Coding of wildcards......................................90
     A.2 ASN.1 syntax specification...............................92
     A.3 Digit maps and path names...............................111
   ANNEX B Text encoding of the protocol.........................113
     B.1 Coding of wildcards.....................................113
     B.2 ABNF specification......................................113
     B.3 Hexadecimal octet coding................................127
     B.4 Hexadecimal octet sequence..............................127
   ANNEX C Tags for media stream properties......................128
     C.1 General media attributes................................128
     C.2 Mux properties..........................................130
     C.3 General bearer properties...............................130
     C.4 General ATM properties..................................130
     C.5 Frame Relay.............................................134
     C.6 IP......................................................134
     C.7 ATM AAL2................................................134
     C.8 ATM AAL1................................................136
     C.9 Bearer capabilities.....................................137
     C.10 AAL5 properties........................................147
     C.11 SDP equivalents........................................148
     C.12 H.245..................................................149
   ANNEX D Transport over IP.....................................150
     D.1 Transport over IP/UDP using Application Level Framing ..150
       D.1.1 Providing At-Most-Once functionality................150
       D.1.2 Transaction identifiers and three-way handshake.....151
       D.1.3 Computing retransmission timers.....................152
       D.1.4 Provisional responses...............................153
       D.1.5 Repeating Requests, Responses and Acknowledgements..153
     D.2 Using TCP...............................................155
       D.2.1 Providing the At-Most-Once functionality............155
       D.2.2 Transaction identifiers and three-way handshake.....155
       D.2.3 Computing retransmission timers.....................156
       D.2.4 Provisional responses...............................156
       D.2.5 Ordering of commands................................156
   ANNEX E  Basic packages.......................................157
     E.1 Generic.................................................157
     E.2 Base Root Package.......................................159
     E.3 Tone Generator Package..................................161
     E.4 Tone Detection Package..................................163
     E.5 Basic DTMF Generator Package............................166
     E.6 DTMF detection Package..................................167
     E.7 Call Progress Tones Generator Package...................169
     E.8 Call Progress Tones Detection Package...................171
     E.9 Analog Line Supervision Package.........................172
     E.10 Basic Continuity Package...............................175
     E.11 Network Package........................................178
     E.12 RTP Package............................................180

     E.13 TDM Circuit Package....................................182
   APPENDIX I EXAMPLE CALL FLOWS (INFORMATIVE)...................184
     A.1 Residential Gateway to Residential Gateway Call.........184
       A.1.1 Programming Residential GW Analog Line Terminations
             for Idle Behavior...................................184
       A.1.2 Collecting Originator Digits and Initiating
             Termination.........................................186
   APPENDIX II  Changes From RFC 3015............................195
   Intellectual Property Rights..................................210
   Acknowledgments...............................................211
   Authors' Addresses............................................212
   Full Copyright Statement......................................213

1  Scope

   The present document, which is identical to the published version of
   ITU-T Recommendation H.248.1 (03/2002) except as noted below, defines
   the protocols used between elements of a physically decomposed
   multimedia gateway.  There are no functional differences from a
   system view between a decomposed gateway, with distributed sub-
   components potentially on more than one physical device, and a
   monolithic gateway such as described in ITU-T Recommendation H.246.
   This document does not define how gateways, multipoint control units
   or interactive voice response units (IVRs) work.  Instead it creates
   a general framework that is suitable for these applications.

   Packet network interfaces may include IP, ATM or possibly others.
   The interfaces will support a variety of Switched Circuit Network
   (SCN) signalling systems, including tone signalling, ISDN, ISUP, QSIG
   and GSM.  National variants of these signalling systems will be
   supported where applicable.

1.1 Changes From RFC 3015

   The differences between this document and RFC 3015 are documented in
   Appendix II.

1.2 Differences From ITU-T Recommendation H.248.1 (03/2002)

   This document differs from the corresponding ITU-T publication in the
   following respects:

   -  Added IETF front matter in place of the corresponding ITU-T
      material.

   -  The ITU-T summary is too H.323-specific and has been omitted.

   -  The IETF conventions have been stated as governing this document.
      As discussed in section 5 below, this gives slightly greater
      strength to "should" requirements.

   -  The Scope section (just above) has been edited slightly to suit
      its IETF context.

   -  Added normative references to RFCs 2026 and 2119.

   -  Figures 4, 5, and 6 show the centre of the context for greater
      clarity.  Also added Figure 6a showing an important additional
      example.

   -  Added a paragraph in section 7.1.18 which was approved in the
      Implementor's Guide but lost inadvertently in the ITU-T approved
      version.

   -  This document incorporates corrections to the informative examples
      in Appendix I which also appear in H.248.1 version 2, but which
      were not picked up in H.248.1 (03/2002).

   -  This document includes a new Appendix II listing all the changes
      from RFC 3015.

   -  This document includes an Acknowledgements section listing the
      authors of RFC 3015 but also many other people who contributed to
      the development of the Megaco/H.248.x protocol.

   -  Moved the Intellectual Property declaration to its usual place in
      an IETF document and added a reference to declarations on the IETF
      web site.

2  References

   The following ITU-T Recommendations and other references contain
   provisions which, through reference in this text, constitute
   provisions of this RFC.  At the time of publication, the editions
   indicated were valid.  All Recommendations and other references are
   subject to revision; all users of this RFC are therefore encouraged
   to investigate the possibility of applying the most recent edition of
   the Recommendations and other references listed below.  A list of the
   currently valid ITU-T Recommendations is regularly published.

   2.1        GEN0202   Added reference to X.690.

   2.2         IGDUB    Added informative references to Q.724, Q.764,
                        and Q.1902.4.

   4          IG0601    Added expansion of ALF.

   5          TTPOST    Gave priority to IETF conventions (added at
                        start of document).

   6.1.1      IG0601    Added text regarding use of wildcards for
                        context identifiers.  (This information
                        already appeared in section 8.1.2.  The IG
                        change subsequently disappeared.)

   6.1.1      IG1100    Added ranking of priority values.

3  Definitions

   This document defines the following terms:

   Access gateway:
   A type of gateway that provides a User-Network Interface (UNI) such
   as ISDN.

   Descriptor:
   A syntactic element of the protocol that groups related properties.
   For instance, the properties of a media flow on the MG can be set by
   the MGC by including the appropriate descriptor in a command.

   Media Gateway (MG):
   The media gateway converts media provided in one type of network to
   the format required in another type of network.  For example, a MG
   could terminate bearer channels from a switched circuit network
   (e.g., DS0s) and media streams from a packet network (e.g., RTP
   streams in an IP network).  This gateway may be capable of processing
   audio, video and T.120 alone or in any combination, and will be
   capable of full duplex media translations.  The MG may also play
   audio/video messages and perform other IVR functions, or may perform
   media conferencing.

   Media Gateway Controller (MGC):
   Controls the parts of the call state that pertain to connection
   control for media channels in a MG.

   Multipoint Control Unit (MCU):
   An entity that controls the setup and coordination of a multi-user
   conference that typically includes processing of audio, video and
   data.

   Residential gateway:
   A gateway that interworks an analogue line to a packet network.  A
   residential gateway typically contains one or two analogue lines and
   is located at the customer premises.

   SCN FAS signalling gateway:
   This function contains the SCN Signalling Interface that terminates
   SS7, ISDN or other signalling links where the call control channel
   and bearer channels are collocated in the same physical span.

   SCN NFAS signalling gateway:
   This function contains the SCN Signalling Interface that terminates
   SS7 or other signalling links where the call control channels are
   separated from bearer channels.

   Stream:
   Bidirectional media or control flow received/sent by a media gateway
   as part of a call or conference.

   Trunk:
   A communication channel between two switching systems such as a DS0
   on a T1 or E1 line.

   Trunking gateway:
   A gateway between SCN network and packet network that typically
   terminates a large number of digital circuits.

4  Abbreviations

   This RFC document uses the following abbreviations:

   ALF   Application Layer Framing

   ATM   Asynchronous Transfer Mode

   CAS   Channel Associated Signalling

   DTMF  Dual Tone Multi-Frequency

   FAS   Facility Associated Signalling

   GSM   Global System for Mobile communications

   GW    GateWay

   IANA  Internet Assigned Numbers Authority (superseded by Internet
         Corporation for Assigned Names and Numbers - ICANN)

   IP    Internet Protocol

   ISUP  ISDN User Part

   IVR   Interactive Voice Response

   MG    Media Gateway

   MGC   Media Gateway Controller

   NFAS  Non-Facility Associated Signalling

   PRI   Primary Rate Interface

   PSTN  Public Switched Telephone Network

   QoS   Quality of Service

   RTP   Real-time Transport Protocol

   SCN   Switched Circuit Network

   SG    Signalling Gateway

   SS7   Signalling System No. 7

5  Conventions

   In the H.248.1 Recommendation, "SHALL" refers to a mandatory
   requirement, while "SHOULD" refers to a suggested but optional
   feature or procedure.  The term "MAY" refers to an optional course of
   action without expressing a preference.  Note that these definition
   are overridden in the present document by the RFC 2119 conventions
   stated at the beginning of this document.  RFC 2119 has a more
   precise definition of "should" than is provided by the ITU-T.

6  Connection model

   The connection model for the protocol describes the logical entities,
   or objects, within the Media Gateway that can be controlled by the
   Media Gateway Controller.  The main abstractions used in the
   connection model are Terminations and Contexts.

   A Termination sources and/or sinks one or more streams.  In a
   multimedia conference, a Termination can be multimedia and sources or
   sinks multiple media streams.  The media stream parameters, as well
   as modem, and bearer parameters are encapsulated within the
   Termination.

   A Context is an association between a collection of Terminations.
   There is a special type of Context, the null Context, which contains
   all Terminations that are not associated to any other Termination.
   For instance, in a decomposed access gateway, all idle lines are
   represented by Terminations in the null Context.

   Following is a graphical depiction of these concepts.  The diagram of
   Figure 1 gives several examples and is not meant to be an
   all-inclusive illustration.  The asterisk box in each of the Contexts
   represents the logical association of Terminations implied by the
   Context.

         +------------------------------------------------------+
         |Media Gateway                                         |
         | +-------------------------------------------------+  |
         | |Context                          +-------------+ |  |
         | |                                 | Termination | |  |
         | |                                 |-------------| |  |
         | |  +-------------+             +->| SCN Bearer  |<---+->
         | |  | Termination |   +-----+   |  |   Channel   | |  |
         | |  |-------------|   |     |---+  +-------------+ |  |
       <-+--->| RTP Stream  |---|  *  |                      |  |
         | |  |             |   |     |---+  +-------------+ |  |
         | |  +-------------+   +-----+   |  | Termination | |  |
         | |                              |  |-------------| |  |
         | |                              +->| SCN Bearer  |<---+->
         | |                                 |   Channel   | |  |
         | |                                 +-------------+ |  |
         | +-------------------------------------------------+  |
         |                                                      |
         |                                                      |
         |                    +------------------------------+  |
         |   (NULL Context)   |Context                       |  |
         |  +-------------+   |              +-------------+ |  |
         |  | Termination |   | +-----+      | Termination | |  |
         |  |-------------|   | |     |      |-------------| |  |
         |  | SCN Bearer  |   | |  *  |------| SCN Bearer  |<---+->
         |  |   Channel   |   | |     |      |   Channel   | |  |
         |  +-------------+   | +-----+      +-------------+ |  |
         |                    +------------------------------+  |
         |                                                      |
         |                                                      |
         | +-------------------------------------------------+  |
         | |Context                                          |  |
         | |  +-------------+                +-------------+ |  |
         | |  | Termination |   +-----+      | Termination | |  |
         | |  |-------------|   |     |      |-------------| |  |
       <-+--->| SCN Bearer  |---|  *  |------| SCN Bearer  |<---+->
         | |  |   Channel   |   |     |      |   Channel   | |  |
         | |  +-------------+   +-----+      +-------------+ |  |
         | +-------------------------------------------------+  |
         | ___________________________________________________  |
         +------------------------------------------------------+

            Figure 1: Examples of Megaco/H.248 Connection Model

   The example in Figure 2 shows an example of one way to accomplish a
   call-waiting scenario in a decomposed access gateway, illustrating
   the relocation of a Termination between Contexts.  Terminations T1
   and T2 belong to Context C1 in a two-way audio call.  A second audio
   call is waiting for T1 from Termination T3.  T3 is alone in Context
   C2.  T1 accepts the call from T3, placing T2 on hold.  This action
   results in T1 moving into Context C2, as shown in Figure 3.

         +------------------------------------------------------+
         |Media Gateway                                         |
         | +-------------------------------------------------+  |
         | |Context C1                                       |  |
         | |  +-------------+                +-------------+ |  |
         | |  | Term. T2    |   +-----+      | Term. T1    | |  |
         | |  |-------------|   |     |      |-------------| |  |
       <-+--->| RTP Stream  |---|  *  |------| SCN Bearer  |<---+->
         | |  |             |   |     |      |   Channel   | |  |
         | |  +-------------+   +-----+      +-------------+ |  |
         | +-------------------------------------------------+  |
         |                                                      |
         | +-------------------------------------------------+  |
         | |Context C2                                       |  |
         | |                                 +-------------+ |  |
         | |                    +-----+      | Term. T3    | |  |
         | |                    |     |      |-------------| |  |
         | |                    |  *  |------| SCN Bearer  |<---+->
         | |                    |     |      |   Channel   | |  |
         | |                    +-----+      +-------------+ |  |
         | +-------------------------------------------------+  |
         +------------------------------------------------------+

     Figure 2: Example Call Waiting Scenario / Alerting Applied to T1

         +------------------------------------------------------+
         |Media Gateway                                         |
         | +-------------------------------------------------+  |
         | |Context C1                                       |  |
         | |  +-------------+                                |  |
         | |  | Term. T2    |   +-----+                      |  |
         | |  |-------------|   |     |                      |  |
       <-+--->| RTP Stream  |---|  *  |                      |  |
         | |  |             |   |     |                      |  |
         | |  +-------------+   +-----+                      |  |
         | +-------------------------------------------------+  |
         |                                                      |
         | +-------------------------------------------------+  |
         | |Context C2                                       |  |
         | |  +-------------+                +-------------+ |  |
         | |  | Term. T1    |   +-----+      | Term. T3    | |  |
         | |  |-------------|   |     |      |-------------| |  |
       <-+--->| SCN Bearer  |---|  *  |------| SCN Bearer  |<---+->
         | |  |   Channel   |   |     |      |   Channel   | |  |
         | |  +-------------+   +-----+      +-------------+ |  |
         | +-------------------------------------------------+  |
         +------------------------------------------------------+

          Figure 3. Example Call Waiting Scenario / Answer by T1

6.1   Contexts

   A Context is an association between a number of Terminations.  The
   Context describes the topology (who hears/sees whom) and the media
   mixing and/or switching parameters if more than two Terminations are
   involved in the association.

   There is a special Context called the null Context.  It contains
   Terminations that are not associated to any other Termination.
   Terminations in the null Context can have their parameters examined
   or modified, and may have events detected on them.

   In general, an Add command is used to add Terminations to Contexts.
   If the MGC does not specify an existing Context to which the
   Termination is to be added, the MG creates a new Context.  A
   Termination may be removed from a Context with a Subtract command,
   and a Termination may be moved from one Context to another with a
   Move command.  A Termination SHALL exist in only one Context at a
   time.

   The maximum number of Terminations in a Context is a MG property.
   Media gateways that offer only point-to-point connectivity might
   allow at most two Terminations per Context.  Media gateways that
   support multipoint conferences might allow three or more Terminations
   per Context.

6.1.1 Context attributes and descriptors

   The attributes of Contexts are:

   -  ContextID.

   -  The topology (who hears/sees whom).

      The topology of a Context describes the flow of media between the
      Terminations within a Context.  In contrast, the mode of a
      Termination (send/receive/...) describes the flow of the media at
      the ingress/egress of the media gateway.

   -  The priority is used for a Context in order to provide the MG with
      information about a certain precedence handling for a Context.
      The MGC can also use the priority to control autonomously the
      traffic precedence in the MG in a smooth way in certain
      situations (e.g., restart), when a lot of Contexts must be handled
      simultaneously.  Priority 0 is the lowest priority and a priority
      of 15 is the highest priority.

   -  An indicator for an emergency call is also provided to allow a
      preference handling in the MG.

6.1.2 Creating, deleting and modifying Contexts

   The protocol can be used to (implicitly) create Contexts and modify
   the parameter values of existing Contexts.  The protocol has commands
   to add Terminations to Contexts, subtract them from Contexts, and to
   move Terminations between Contexts.  Contexts are deleted implicitly
   when the last remaining Termination is subtracted or moved out.

   6.2        TTPOST    Added asterisks to multiplexing diagrams to
                        indicate centre of context.  Added Figure 6a
                        showing cascading of multiplexes.

6.2.1 Termination dynamics

   The protocol can be used to create new Terminations and to modify
   property values of existing Terminations.  These modifications
   include the possibility of adding or removing events and/or signals.
   The Termination properties, and events and signals are described in
   the ensuing subclauses.  An MGC can only release/modify Terminations
   and the resources that the Termination represents which it has
   previously seized via, e.g., the Add command.

   6.2.2      IG0601    Added text indicating that ALL does not
                        include ROOT.

   6.2.3      IG1100    Added text indicating what packages a peer can
                        indicate support for, when some of them are
                        extensions of others.

   6.2.4      IG1100    Added Topology and Error Descriptors to table.

   6.2.5       IGDUB    Specified error code to return if ROOT used
                        inappropriately.

7  Commands

   The protocol provides commands for manipulating the logical entities
   of the protocol connection model, Contexts and Terminations.
   Commands provide control at the finest level of granularity supported
   by the protocol.  For example, Commands exist to add Terminations to
   a Context, modify Terminations, subtract Terminations from a Context,
   and audit properties of Contexts or Terminations.  Commands provide
   for complete control of the properties of Contexts and Terminations.
   This includes specifying which events a Termination is to report,
   which signals/actions are to be applied to a Termination and
   specifying the topology of a Context (who hears/sees whom).

   Most commands are for the specific use of the Media Gateway
   Controller as command initiator in controlling Media Gateways as
   command responders.  The exceptions are the Notify and ServiceChange
   commands: Notify is sent from Media Gateway to Media Gateway
   Controller, and ServiceChange may be sent by either entity.  Below is
   an overview of the commands; they are explained in more detail in
   7.2.

   1) Add - The Add command adds a Termination to a Context.  The Add
      command on the first Termination in a Context is used to create a
      Context.

   2) Modify - The Modify command modifies the properties, events and
      signals of a Termination.

   3) Subtract - The Subtract command disconnects a Termination from its
      Context and returns statistics on the Termination's participation
      in the Context.  The Subtract command on the last Termination in a
      Context deletes the Context.

   4) Move - The Move command atomically moves a Termination to another
      Context.

   5) AuditValue - The AuditValue command returns the current state of
      properties, events, signals and statistics of Terminations.

   6) AuditCapabilities - The AuditCapabilities command returns all the
      possible values for Termination properties, events and signals
      allowed by the Media Gateway.

   7) Notify - The Notify command allows the Media Gateway to inform the
      Media Gateway Controller of the occurrence of events in the Media
      Gateway.

   8) ServiceChange - The ServiceChange command allows the Media Gateway
      to notify the Media Gateway Controller that a Termination or group
      of Terminations is about to be taken out of service or has just
      been returned to service.  ServiceChange is also used by the MG to
      announce its availability to a MGC (registration), and to notify
      the MGC of impending or completed restart of the MG.  The MGC may
      announce a handover to the MG by sending it a ServiceChange
      command.  The MGC may also use ServiceChange to instruct the MG to
      take a Termination or group of Terminations in or out of service.

   These commands are detailed in 7.2.1 through 7.2.8.

7.1   Descriptors

   The parameters to a command are termed Descriptors.  A descriptor
   consists of a name and a list of items.  Some items may have values.
   Many Commands share common descriptors.  This subclause enumerates
   these descriptors.  Descriptors may be returned as output from a
   command.  In any such return of descriptor contents, an empty
   descriptor is represented by its name unaccompanied by any list.
   Parameters and parameter usage specific to a given Command type are
   described in the subclause that describes the Command.

   7.1.1      IG1100    Added qualification to explanation of effect
                        of missing Audit Descriptor, excepting
                        Subtract.

7.1.2 Modem descriptor

   The Modem descriptor specifies the modem type and parameters, if any,
   required for use in e.g., H.324 and text conversation.  The
   descriptor includes the following modem types: V.18, V.22, V.22 bis,
   V.32, V.32 bis, V.34, V.90, V.91, Synchronous ISDN, and allows for
   extensions.  By default, no Modem descriptor is present in a
   Termination.

   7.1.3      GEN0202   Changed "inputs" to "bearers" to be consistent
                        with terminology in 6.2.

   7.1.4      IG0601    Small change to make clear that more than one
                        of Local, Remote, and LocalControl can be
                        included in the default streamId.

7.1.5 TerminationState descriptor

   The TerminationState descriptor contains the ServiceStates property,
   the EventBufferControl property and properties of a Termination
   (defined in Packages) that are not stream specific.

   The ServiceStates property describes the overall state of the
   Termination (not stream specific).  A Termination can be in one of
   the following states: "test", "out of service", or "in service".  The
   "test" state indicates that the Termination is being tested.  The
   state "out of service" indicates that the Termination cannot be used
   for traffic.  The state "in service" indicates that a Termination can
   be used or is being used for normal traffic.  "in service" is the
   default state.

   Values assigned to Properties may be simple values
   (integer/string/enumeration) or may be underspecified, where more
   than one value is supplied and the MG may make a choice:

   -  Alternative Values - multiple values in a list, one of which must
      be selected

   -  Ranges - minimum and maximum values, any value between min and max
      must be selected, boundary values included

   -  Greater Than/Less Than - value must be greater/less than specified
      value

   -  CHOOSE Wildcard - the MG chooses from the allowed values for the
      property

   The EventBufferControl property specifies whether events are buffered
   following detection of an event in the Events descriptor, or
   processed immediately.  See 7.1.9 for details.

7.1.6 Stream descriptor

   A Stream descriptor specifies the parameters of a single
   bidirectional stream.  These parameters are structured into three
   descriptors: one that contains Termination properties specific to a
   stream and one each for local and remote flows.  The Stream
   Descriptor includes a StreamID which identifies the stream.  Streams
   are created by specifying a new StreamID on one of the Terminations
   in a Context.  A stream is deleted by setting empty Local and Remote
   descriptors for the stream with ReserveGroup and ReserveValue in
   LocalControl set to "false" on all Terminations in the Context that
   previously supported that stream.

   StreamIDs are of local significance between MGC and MG and they are
   assigned by the MGC.  Within a Context, StreamID is a means by which
   to indicate which media flows are interconnected: streams with the
   same StreamID are connected.

   If a Termination is moved from one Context to another, the effect on
   the Context to which the Termination is moved is the same as in the
   case that a new Termination were added with the same StreamIDs as the
   moved Termination.

   7.1.7      GEN0202   Added text requiring processing of media in
                        any of the reserved formats, where more than
                        one has been reserved in a given stream.

   7.1.8       IGDUB    Added restriction to at most one m= line per
                        session description.

   7.1.9      IG1100    Added note to say event remains active after
                        it has been notified, so long as it is still
                        present in the active Events Descriptor.

7.1.10   EventBuffer descriptor

   The EventBuffer descriptor contains a list of events, with their
   parameters if any, that the MG is requested to detect and buffer when
   EventBufferControl equals LockStep (see 7.1.9).

   7.1.11     IG1100    Deleted text discussing type of Signals List.

   7.1.12     GEN0202   Improved wording of introductory paragraph and
                        added text making content of returned
                        Descriptor clear.

   7.1.14.2   GEN0202   Added text indicating that when the start
                        timer is set to 0, initial digit timing is
                        disabled and the MG waits indefinitely for
                        digits.

   7.1.14.2   GEN0202   Added text pointing out that default digit
                        timer values should be provisioned, but can be
                        overridden in the digit map.

   7.1.14.3   GEN0202   Changed result of long-short digit timer
                        conflict from undefined to long.

   7.1.14.6   IG1100    Clarified that the digit map is provided by
                        the eventDM parameter, which must be present.

   7.1.14.7   GEN0202   Added text clarifying that events covered by
                        the digit map completion event have no side-
                        effects unless separately enabled.

   7.1.14.8   IG0601    Added requirement that the event specification
                        include the eventDM parameter.

7.1.13   ServiceChange descriptor

   The ServiceChangeDescriptor contains the following parameters:

      .  ServiceChangeMethod
      .  ServiceChangeReason
      .  ServiceChangeAddress
      .  ServiceChangeDelay
      .  ServiceChangeProfile
      .  ServiceChangeVersion
      .  ServiceChangeMGCId
      .  TimeStamp
      .  Extension

   See 7.2.8.

7.1.14   DigitMap descriptor

7.1.14.1 DigitMap definition, creation, modification and deletion

   A DigitMap is a dialing plan resident in the Media Gateway used for
   detecting and reporting digit events received on a Termination.  The
   DigitMap descriptor contains a DigitMap name and the DigitMap to be
   assigned.  A digit map may be preloaded into the MG by management
   action and referenced by name in an EventsDescriptor, may be defined
   dynamically and subsequently referenced by name, or the actual
   digitmap itself may be specified in the EventsDescriptor.  It is
   permissible for a digit map completion event within an Events
   descriptor to refer by name to a DigitMap which is defined by a
   DigitMap descriptor within the same command, regardless of the
   transmitted order of the respective descriptors.

   DigitMaps defined in a DigitMapDescriptor can occur in any of the
   standard Termination manipulation Commands of the protocol.  A
   DigitMap, once defined, can be used on all Terminations specified by
   the (possibly wildcarded) TerminationID in such a command.  DigitMaps
   defined on the root Termination are global and can be used on every
   Termination in the MG, provided that a DigitMap with the same name
   has not been defined on the given Termination.  When a DigitMap is
   defined dynamically in a DigitMap descriptor:

   -  A new DigitMap is created by specifying a name that is not yet
      defined.  The value shall be present.

   -  A DigitMap value is updated by supplying a new value for a name
      that is already defined.  Terminations presently using the
      digitmap shall continue to use the old definition; subsequent
      EventsDescriptors specifying the name, including any
      EventsDescriptor in the command containing the DigitMap
      descriptor, shall use the new one.

   -  A DigitMap is deleted by supplying an empty value for a name that
      is already defined.  Terminations presently using the digitmap
      shall continue to use the old definition.

7.1.14.2 DigitMap Timers

   The collection of digits according to a DigitMap may be protected by
   three timers, viz. a start timer (T), short timer (S), and long timer
   (L).

   1) The start timer (T) is used prior to any digits having been
      dialed.  If the start timer is overridden with the value set to
      zero (T=0), then the start timer shall be disabled.  This implies
      that the MG will wait indefinitely for digits.

   2) If the Media Gateway can determine that at least one more digit is
      needed for a digit string to match any of the allowed patterns in
      the digit map, then the interdigit timer value should be set to a
      long (L) duration (e.g., 16 seconds).

   3) If the digit string has matched one of the patterns in a digit
      map, but it is possible that more digits could be received which
      would cause a match with a different pattern, then instead of
      reporting the match immediately, the MG must apply the short timer
      (S) and wait for more digits.

   The timers are configurable parameters to a DigitMap.  Default values
   of these timers should be provisioned on the MG, but can be
   overridden by values specified within the DigitMap.

7.1.14.3 DigitMap Syntax

   The formal syntax of the digit map is described by the DigitMap rule
   in the formal syntax description of the protocol (see Annex A and
   Annex B).  A DigitMap, according to this syntax, is defined either by
   a string or by a list of strings.  Each string in the list is an
   alternative event sequence, specified either as a sequence of digit
   map symbols or as a regular expression of digit map symbols.  These
   digit map symbols, the digits "0" through "9" and letters "A" through
   a maximum value depending on the signalling system concerned, but
   never exceeding "K", correspond to specified events within a package

   which has been designated in the Events descriptor on the Termination
   to which the digit map is being applied.  (The mapping between events
   and digit map symbols is defined in the documentation for packages
   associated with channel-associated signalling systems such as DTMF,
   MF, or R2.  Digits "0" through "9" MUST be mapped to the
   corresponding digit events within the signalling system concerned.
   Letters should be allocated in logical fashion, facilitating the use
   of range notation for alternative events.)

   The letter "x" is used as a wildcard, designating any event
   corresponding to symbols in the range "0"-"9".  The string may also
   contain explicit ranges and, more generally, explicit sets of
   symbols, designating alternative events any one of which satisfies
   that position of the digit map.  Finally, the dot symbol "." stands
   for zero or more repetitions of the event selector (event, range of
   events, set of alternative events, or wildcard) that precedes it.  As
   a consequence of the third timing rule above, inter-event timing
   while matching a terminal dot symbol uses the short timer by default.

   In addition to these event symbols, the string may contain "S" and
   "L" inter-event timing specifiers and the "Z" duration modifier.  "S"
   and "L" respectively indicate that the MG should use the short (S)
   timer or the long (L) timer for subsequent events, overriding the
   timing rules described above.  If an explicit timing specifier is in
   effect in one alternative event sequence, but none is given in any
   other candidate alternative, the timer value set by the explicit
   timing specifier must be used.  If all sequences with explicit timing
   controls are dropped from the candidate set, timing reverts to the
   default rules given above.  Finally, if conflicting timing specifiers
   are in effect in different alternative sequences, the long timer
   shall be used.

   A "Z" designates a long duration event: placed in front of the
   symbol(s) designating the event(s) which satisfy a given digit
   position, it indicates that that position is satisfied only if the
   duration of the event exceeds the long-duration threshold.  The value
   of this threshold is assumed to be provisioned in the MG.

7.1.14.4 DigitMap Completion Event

   A digit map is active while the Events descriptor which invoked it is
   active and it has not completed.  A digit map completes when:

   -  a timer has expired; or

   -  an alternative event sequence has been matched and no other
      alternative event sequence in the digit map could be matched
      through detection of an additional event (unambiguous match); or

   -  an event has been detected such that a match to a complete
      alternative event sequence of the digit map will be impossible no
      matter what additional events are received.

   Upon completion, a digit map completion event as defined in the
   package providing the events being mapped into the digit map shall be
   generated.  At that point the digit map is deactivated.  Subsequent
   events in the package are processed as per the currently active event
   processing mechanisms.

7.1.14.5 DigitMap Procedures

   Pending completion, successive events shall be processed according to
   the following rules:

   1) The "current dial string", an internal variable, is initially
      empty.  The set of candidate alternative event sequences includes
      all of the alternatives specified in the digit map.

   2) At each step, a timer is set to wait for the next event, based
      either on the default timing rules given above or on explicit
      timing specified in one or more alternative event sequences.  If
      the timer expires and a member of the candidate set of
      alternatives is fully satisfied, a timeout completion with full
      match is reported.  If the timer expires and part or none of any
      candidate alternative is satisfied, a timeout completion with
      partial match is reported.

   3) If an event is detected before the timer expires, it is mapped to
      a digit string symbol and provisionally added to the end of the
      current dial string.  The duration of the event (long or not long)
      is noted if and only if this is relevant in the current symbol
      position (because at least one of the candidate alternative event
      sequences includes the "Z" modifier at this position in the
      sequence).

   4) The current dial string is compared to the candidate alternative
      event sequences.  If and only if a sequence expecting a
      long-duration event at this position is matched (i.e., the event
      had long duration and met the specification for this position),
      then any alternative event sequences not specifying a long
      duration event at this position are discarded, and the current
      dial string is modified by inserting a "Z" in front of the symbol
      representing the latest event.   Any sequence expecting a long-
      duration event at this position but not matching the observed
      event is discarded from the candidate set.  If alternative event
      sequences not specifying a long duration event in the given

      position remain in the candidate set after application of the
      above rules, the observed event duration is treated as irrelevant
      in assessing matches to them.

   5) If exactly one candidate remains and it has been fully matched, a
      completion event is generated indicating an unambiguous match.  If
      no candidates remain, the latest event is removed from the current
      dial string and a completion event is generated indicating full
      match if one of the candidates from the previous step was fully
      satisfied before the latest event was detected, or partial match
      otherwise.  The event removed from the current dial string will
      then be reported as per the currently active event processing
      mechanisms.

   6) If no completion event is reported out of step 5, processing
      returns to step 2.

7.1.14.6 DigitMap Activation

   A digit map is activated whenever a new Event descriptor is applied
   to the Termination or embedded Event descriptor is activated, and
   that Event descriptor contains a digit map completion event.  The
   digit map completion event contains an eventDM field in the requested
   actions field.  Each new activation of a digit map begins at step 1
   of the above procedure, with a clear current dial string.  Any
   previous contents of the current dial string from an earlier
   activation are lost.

   A digit map completion event that does not contain an eventDM field
   in its requested actions field is considered an error.  Upon receipt
   of such an event in an EventsDescriptor, a MG shall respond with an
   error response, including Error 457 - Missing parameter in signal or
   event.

7.1.14.7 Interaction Of DigitMap and Event Processing

   While the digit map is activated, detection is enabled for all events
   defined in the package containing the specified digit map completion
   event.  Normal event behaviour (e.g., stopping of signals unless the
   digit completion event has the KeepActive flag enabled) continues to
   apply for each such event detected, except that:

   -  the events in the package containing the specified digit map
      completion event other than the completion event itself are not
      individually notified and have no side-effects unless separately
      enabled; and

   -  an event that triggers a partial match completion event is not
      recognized and therefore has no side effects until reprocessed
      following the recognition of the digit map completion event.

7.1.14.8 Wildcards

   Note that if a package contains a digit map completion event, then an
   event specification consisting of the package name with a wildcarded
   ItemID (Property Name) will activate a digit map; to that end, the
   event specification must include an eventDM field according to
   section 7.1.14.6.  If the package also contains the digit events
   themselves, this form of event specification will cause the
   individual events to be reported to the MGC as they are detected.

7.1.14.9 Example

   As an example, consider the following dial plan:

   0                      Local operator

   00                     Long-distance operator

   xxxx                   Local extension number (starts with 1-7)

   8xxxxxxx               Local number

   #xxxxxxx               Off-site extension

   *xx                    Star services

   91xxxxxxxxxx           Long-distance number

   9011 + up to 15 digits International number



   If the DTMF detection package described in E.6 is used to collect the
   dialed digits, then the dialing plan shown above results in the
   following digit map:

    (0| 00|[1-7]xxx|8xxxxxxx|Fxxxxxxx|Exx|91xxxxxxxxxx|9011x.)

7.1.15   Statistics descriptor

   The Statistics Descriptor provides information describing the status
   and usage of a Termination during its existence within a specific
   Context.  There is a set of standard statistics kept for each
   Termination where appropriate (number of octets sent and received for

   example).  The particular statistical properties that are reported
   for a given Termination are determined by the Packages realized by
   the Termination.  By default, statistics are reported when the
   Termination is Subtracted from the Context.  This behaviour can be
   overridden by including an empty AuditDescriptor in the Subtract
   command.  Statistics may also be returned from the AuditValue
   command, or any Add/Move/Modify command using the Audit descriptor.

   Statistics are cumulative; reporting Statistics does not reset them.
   Statistics are reset when a Termination is Subtracted from a Context.

7.1.16   Packages descriptor

   Used only with the AuditValue command, the PackageDescriptor returns
   a list of Packages realized by the Termination.

   7.1.17     GEN0202   Deleted provision that time is expressed in
                        UTC (since intention was to use format, not
                        time zone).

   7.1.18     IG1100    Added text clarifying effect of not mentioning
              TTPOST    a termination in a topology Descriptor, and
                        default topology for a new termination.  (This
                        text got lost between the Dublin meeting and
                        the production of H.248 Amendment 1 out of the
                        Geneva 02/02 meeting.  It has been added back
                        to the present document.)

   7.1.19     IG0601    Added paragraph giving guidance on level at
                        which errors should be reported.

   7.2        IG1100    Noted possibility of Error Descriptor in reply
                        to any command.

   7.2.1      IG1100    Removed restriction on use of CHOOSE wildcard.

   7.2.2      GEN0202   Added text on side-effects of Modify of a
                        multiplexing termination.

   7.2.3       IGDUB    Added text clarifying effect of empty
                        AuditDescriptor in Subtract.

   7.2.4      GEN0202   Added text on side-effects of Move of a
                        multiplexing termination.

   7.2.5      IG1100    Added table entry (ALL, specific) to determine
                        context in which termination currently
                        resides.

   7.2.6      GEN0202   Added table similar to that in 7.2.5.

   7.2.7      IG1100    Noted possibility of sending Error Descriptor
                        in Notify.

   7.2.8       IGDUB    Corrected "gateway" to "MGC" in discussion of
                        returned ServiceChangeMgcId parameter.

7.2.9 Manipulating and Auditing Context Attributes

   The commands of the protocol as discussed in the preceding subclauses
   apply to Terminations.  This subclause specifies how Contexts are
   manipulated and audited.

   Commands are grouped into actions (see clause 8).  An action applies
   to one Context.  In addition to commands, an action may contain
   Context manipulation and auditing instructions.

   An action request sent to a MG may include a request to audit
   attributes of a Context.  An action may also include a request to
   change the attributes of a Context.

   The Context properties that may be included in an action reply are
   used to return information to a MGC.  This can be information
   requested by an audit of Context attributes or details of the effect
   of manipulation of a Context.

   If a MG receives an action which contains both a request to audit
   context attributes and a request to manipulate those attributes, the
   response SHALL include the values of the attributes after processing
   the manipulation request.

7.2.10   Generic Command Syntax

   The protocol can be encoded in a binary format or in a text format.
   MGCs should support both encoding formats.  MGs may support both
   formats.

   The protocol syntax for the binary format of the protocol is defined
   in Annex A.  Annex C specifies the encoding of the Local and Remote
   descriptors for use with the binary format.

   A complete ABNF of the text encoding of the protocol per RFC 2234 is
   given in Annex B.  SDP is used as the encoding of the Local and
   Remote descriptors for use with the text encoding as modified in
   7.1.8.

   7.3        IG0601    Removed error code documentation to Annex L
              ITUPOST   (now H.248.8).

   8          IG1100    Added requirement that an Action be non-empty.

   8          GEN0202   Added context properties and context property
                        audit requests to commands as potential
                        contents of actions.

8  Transactions

   Commands between the Media Gateway Controller and the Media Gateway
   are grouped into Transactions, each of which is identified by a
   TransactionID.  Transactions consist of one or more Actions.  An
   Action consists of a non-empty series of Commands, Context property
   modifications, or Context property audits that are limited to
   operating within a single Context.  Consequently, each Action
   typically specifies a ContextID.  However, there are two
   circumstances where a specific ContextID is not provided with an
   Action.  One is the case of modification of a Termination outside of
   a Context.  The other is where the controller requests the gateway to
   create a new Context.  Figure 8 is a graphic representation of the
   Transaction, Action and Command relationships.

      +----------------------------------------------------------+
      | Transaction x                                            |
      |  +----------------------------------------------------+  |
      |  | Action 1                                           |  |
      |  | +---------+  +---------+  +---------+  +---------+ |  |
      |  | | Command |  | Command |  | Command |  | Command | |  |
      |  | |    1    |  |    2    |  |    3    |  |    4    | |  |
      |  | +---------+  +---------+  +---------+  +---------+ |  |
      |  +----------------------------------------------------+  |
      |                                                          |
      |  +----------------------------------------------------+  |
      |  | Action 2                                           |  |
      |  | +---------+                                        |  |
      |  | | Command |                                        |  |
      |  | |    1    |                                        |  |
      |  | +---------+                                        |  |
      |  +----------------------------------------------------+  |
      |                                                          |
      |  +----------------------------------------------------+  |
      |  | Action 3                                           |  |
      |  | +---------+  +---------+  +---------+              |  |
      |  | | Command |  | Command |  | Command |              |  |
      |  | |    1    |  |    2    |  |    3    |              |  |
      |  | +---------+  +---------+  +---------+              |  |
      |  +----------------------------------------------------+  |
      +----------------------------------------------------------+

               Figure 8: Transactions, Actions and Commands

   Transactions are presented as TransactionRequests.  Corresponding
   responses to a TransactionRequest are received in a single reply,
   possibly preceded by a number of TransactionPending messages (see
   8.2.3).

   Transactions guarantee ordered Command processing.  That is, Commands
   within a Transaction are executed sequentially.  Ordering of
   Transactions is NOT guaranteed - transactions may be executed in any
   order, or simultaneously.

   At the first failing Command in a Transaction, processing of the
   remaining Commands in that Transaction stops.  If a command contains
   a wildcarded TerminationID, the command is attempted with each of the
   actual TerminationIDs matching the wildcard.  A response within the
   TransactionReply is included for each matching TerminationID, even if
   one or more instances generated an error.  If any TerminationID
   matching a wildcard results in an error when executed, any commands
   following the wildcarded command are not attempted.

   Commands may be marked as "Optional" which can override this
   behaviour - if a command marked as Optional results in an error,
   subsequent commands in the Transaction will be executed.  If a
   command fails, the MG shall as far as possible restore the state that
   existed prior to the attempted execution of the command before
   continuing with command processing.

   A TransactionReply includes the results for all of the Commands in
   the corresponding TransactionRequest.  The TransactionReply includes
   the return values for the Commands that were executed successfully,
   and the Command and error descriptor for any Command that failed.

   TransactionPending is used to periodically notify the receiver that a
   Transaction has not completed yet, but is actively being processed.

   Applications SHOULD implement an application level timer per
   transaction.  Expiration of the timer should cause a retransmission
   of the request.  Receipt of a Reply should cancel the timer.  Receipt
   of Pending should restart the timer.

8.1   Common parameters

8.1.1 Transaction Identifiers

   Transactions are identified by a TransactionID, which is assigned by
   sender and is unique within the scope of the sender.  A response
   containing an error descriptor to indicate that the TransactionID is
   missing in a request shall use TransactionID 0 in the corresponding
   TransactionReply.

   8.1.2      GEN0202   Added prohibition on using partial contextIDs
                        with ALL wildcards.

8.2   Transaction Application Programming Interface

   Following is an Application Programming Interface (API) describing
   the Transactions of the protocol.  This API is shown to illustrate
   the Transactions and their parameters and is not intended to specify
   implementation (e.g., via use of blocking function calls).  It will
   describe the input parameters and return values expected to be used
   by the various Transactions of the protocol from a very high level.
   Transaction syntax and encodings are specified in later subclauses.

8.2.1 TransactionRequest

   The TransactionRequest is invoked by the sender.  There is one
   Transaction per request invocation.  A request contains one or more
   Actions, each of which specifies its target Context and one or more
   Commands per Context.

     TransactionRequest(TransactionId {
         ContextID {Command ... Command},
            . . .
         ContextID {Command ... Command } })

   The TransactionID parameter must specify a value for later
   correlation with the TransactionReply or TransactionPending response
   from the receiver.

   The ContextID parameter must specify a value to pertain to all
   Commands that follow up to either the next specification of a
   ContextID parameter or the end of the TransactionRequest, whichever
   comes first.

   The Command parameter represents one of the Commands mentioned in 7.2
   (Command Application Programming Interface).

   8.2.2      IG0601    Corrected Actions to Commands when discussing
                        partially-understood action.

8.2.3 TransactionPending

   The receiver invokes the TransactionPending.  A TransactionPending
   indicates that the Transaction is actively being processed, but has
   not been completed.  It is used to prevent the sender from assuming
   the TransactionRequest was lost where the Transaction will take some
   time to complete.

     TransactionPending(TransactionID { } )

   The TransactionID parameter must be the same as that of the
   corresponding TransactionRequest.  A property of root
   (normalMGExecutionTime) is settable by the MGC to indicate the
   interval within which the MGC expects a response to any transaction
   from the MG.  Another property (normalMGCExecutionTime) is settable
   by the MGC to indicate the interval within which the MG should expect
   a response to any transaction from the MGC.  Senders may receive more
   than one TransactionPending for a command.  If a duplicate request is

   received when pending, the responder may send a duplicate pending
   immediately, or continue waiting for its timer to trigger another
   TransactionPending.

   8.3        IG0601    Added text expanding on independence of
                        transactions from messages.

   9          ITUPOST   Indicated that additional transports may be
                        defined in separate Recommendations as well as
                        annexes to the primary specification.

   9          IG0601    Gave specific example of "request source
                        address" for IP.

9  Transport

   The transport mechanism for the protocol should allow the reliable
   transport of transactions between a MGC and MG.  The transport shall
   remain independent of what particular commands are being sent and
   shall be applicable to all application states.  There are several
   transports defined for the protocol, which are defined in Annexes to
   this RFC and other Recommendations of the H.248
   sub-series.  Additional Transports may be defined as additional

   Recommendations of the H.248 sub-series.  For transport of the
   protocol over IP, MGCs shall implement both TCP and UDP/ALF, a MG
   shall implement TCP or UDP/ALF or both.

   The MG is provisioned with a name or address (such as DNS name or IP
   address) of a primary and zero or more secondary MGCs (see 7.2.8)
   that is the address the MG uses to send messages to the MGC.  If TCP
   or UDP is used as the protocol transport and the port to which the
   initial ServiceChange request is to be sent is not otherwise known,
   that request should be sent to the default port number for the
   protocol.  This port number is 2944 for text-encoded operation or
   2945 for binary-encoded operation, for either UDP or TCP.  The MGC
   receives the message containing the ServiceChange request from the MG
   and can determine the MG's address from it.  As described in 7.2.8,
   either the MG or the MGC may supply an address in the
   ServiceChangeAddress parameter to which subsequent transaction
   requests must be addressed, but responses (including the response to
   the initial ServiceChange request) must always be sent back to the
   address which was the source of the corresponding request.  For
   example, in IP networks, this is the source address in the IP header
   and the source port number in the TCP/UDP/SCTP header.

   9.1        IG0601    Restored restriction, but noted that it
                        applied only to transport not guaranteeing
                        ordered delivery.

9.2   Protection against Restart Avalanche

   In the event that a large number of Media Gateways are powered on
   simultaneously and they were to all initiate a ServiceChange
   transaction, the Media Gateway Controller would very likely be
   swamped, leading to message losses and network congestion during the
   critical period of service restoration.  In order to prevent such
   avalanches, the following behaviour is suggested:

   1) When a Media Gateway is powered on, it should initiate a restart
      timer to a random value, uniformly distributed between 0 and a
      maximum waiting delay (MWD).  Care should be taken to avoid
      synchronicity of the random number generation between multiple
      Media Gateways that would use the same algorithm.

   2) The Media Gateway should then wait for either the end of this
      timer or the detection of a local user activity, such as for
      example an off-hook transition on a residential Media Gateway.

   3) When the timer elapses, or when an activity is detected, the Media
      Gateway should initiate the restart procedure.

   The restart procedure simply requires the MG to guarantee that the
   first message that the Media Gateway Controller sees from this MG is
   a ServiceChange message informing the Media Gateway Controller about
   the restart.

     NOTE - The value of MWD is a configuration parameter that depends
     on the type of the Media Gateway.  The following reasoning may be
     used to determine the value of this delay on residential gateways.

   Media Gateway Controllers are typically dimensioned to handle the
   peak hour traffic load, during which, in average, 10% of the lines
   will be busy, placing calls whose average duration is typically 3
   minutes.  The processing of a call typically involves 5 to 6 Media
   Gateway Controller transactions between each Media Gateway and the
   Media Gateway Controller.  This simple calculation shows that the
   Media Gateway Controller is expected to handle 5 to 6 transactions
   for each Termination, every 30 minutes on average, or, to put it
   otherwise, about one transaction per Termination every 5 to 6 minutes
   on average.  This suggests that a reasonable value of MWD for a
   residential gateway would be 10 to 12 minutes.  In the absence of
   explicit configuration, residential gateways should adopt a value of
   600 seconds for MWD.

   The same reasoning suggests that the value of MWD should be much
   shorter for trunking gateways or for business gateways, because they
   handle a large number of Terminations, and also because the usage
   rate of these Terminations is much higher than 10% during the peak
   busy hour, a typical value being 60%.  These Terminations, during the
   peak hour, are this expected to contribute about one transaction per
   minute to the Media Gateway Controller load.  A reasonable algorithm
   is to make the value of MWD per "trunk" Termination six times shorter
   than the MWD per residential gateway, and also inversely proportional
   to the number of Terminations that are being restarted.  For example
   MWD should be set to 2.5 seconds for a gateway that handles a T1
   line, or to 60 milliseconds for a gateway that handles a T3 line.

10 Security Considerations

   This clause covers security when using the protocol in an IP
   environment.

10.1  Protection of Protocol Connections

   A security mechanism is clearly needed to prevent unauthorized
   entities from using the protocol defined in this RFC for setting up
   unauthorized calls or interfering with authorized calls.  The
   security mechanism for the protocol when transported over IP networks
   is IPsec [RFC 2401 to RFC 2411].

   The AH header [RFC 2402] affords data origin authentication,
   connectionless integrity and optional anti-replay protection of
   messages passed between the MG and the MGC.  The ESP header [RFC
   2406] provides confidentiality of messages, if desired.  For

   instance, the ESP encryption service should be requested if the
   session descriptions are used to carry session keys, as defined in
   SDP.

   Implementations of the protocol defined in this RFC employing the ESP
   header SHALL comply with section 5 of [RFC 2406], which defines a
   minimum set of algorithms for integrity checking and encryption.
   Similarly, implementations employing the AH header SHALL comply with
   section 5 of [RFC 2402], which defines a minimum set of algorithms
   for integrity checking using manual keys.

   Implementations SHOULD use IKE [RFC 2409] to permit more robust
   keying options.  Implementations employing IKE SHOULD support
   authentication with RSA signatures and RSA public key encryption.

   10.2       IG1100    Corrected length of synthesized address field
                        from 10 to 20 hex digits and indicated that
                        calculation should be over entire message, not
                        just one transaction.

10.3  Protection of Media Connections

   The protocol allows the MGC to provide MGs with "session keys" that
   can be used to encrypt the audio messages, protecting against
   eavesdropping.

   A specific problem of packet networks is "uncontrolled barge-in".
   This attack can be performed by directing media packets to the IP
   address and UDP port used by a connection.  If no protection is
   implemented, the packets must be decompressed and the signals must be
   played on the "line side".

   A basic protection against this attack is to only accept packets from
   known sources, checking for example that the IP source address and
   UDP source port match the values announced in the Remote descriptor.
   This has two inconveniences: it slows down connection establishment
   and it can be fooled by source spoofing:

   -  To enable the address-based protection, the MGC must obtain the
      remote session description of the egress MG and pass it to the
      ingress MG.  This requires at least one network round trip, and
      leaves us with a dilemma: either allow the call to proceed without
      waiting for the round trip to complete, and risk for example,
      "clipping" a remote announcement, or wait for the full round trip
      and settle for slower call-set up procedures.

   -  Source spoofing is only effective if the attacker can obtain valid
      pairs of source destination addresses and ports, for example by
      listening to a fraction of the traffic.  To fight source spoofing,
      one could try to control all access points to the network.  But
      this is in practice very hard to achieve.

   An alternative to checking the source address is to encrypt and
   authenticate the packets, using a secret key that is conveyed during
   the call set-up procedure.  This will not slow down the call set-up,
   and provides strong protection against address spoofing.

11 MG-MGC Control Interface

   The control association between MG and MGC is initiated at MG cold
   start, and announced by a ServiceChange message, but can be changed
   by subsequent events, such as failures or manual service events.
   While the protocol does not have an explicit mechanism to support
   multiple MGCs controlling a physical MG, it has been designed to
   support the multiple logical MG (within a single physical MG) that
   can be associated with different MGCs.

11.1  Multiple Virtual MGs

   A physical Media Gateway may be partitioned into one or more Virtual
   MGs.  A virtual MG consists of a set of statically partitioned
   physical Terminations and/or sets of ephemeral Terminations.  A
   physical Termination is controlled by one MGC.  The model does not
   require that other resources be statically allocated, just
   Terminations.  The mechanism for allocating Terminations to virtual
   MGs is a management method outside the scope of the protocol.  Each
   of the virtual MGs appears to the MGC as a complete MG client.

   A physical MG may have only one network interface, which must be
   shared across virtual MGs.  In such a case, the packet/cell side
   Termination is shared.  It should be noted however, that in use, such
   interfaces require an ephemeral instance of the Termination to be
   created per flow, and thus sharing the Termination is
   straightforward.  This mechanism does lead to a complication, namely
   that the MG must always know which of its controlling MGCs should be
   notified if an event occurs on the interface.

   In normal operation, the Virtual MG will be instructed by the MGC to
   create network flows (if it is the originating side), or to expect
   flow requests (if it is the terminating side), and no confusion will
   arise.  However, if an unexpected event occurs, the Virtual MG must
   know what to do with respect to the physical resources it is
   controlling.

   If recovering from the event requires manipulation of a physical
   interface's state, only one MGC should do so.  These issues are
   resolved by allowing any of the MGCs to create EventsDescriptors to
   be notified of such events, but only one MGC can have read/write

   access to the physical interface properties; all other MGCs have
   read-only access.  The management mechanism is used to designate
   which MGC has read/write capability, and is designated the Master
   MGC.

   Each virtual MG has its own Root Termination.  In most cases the
   values for the properties of the Root Termination are independently
   settable by each MGC.  Where there can only be one value, the
   parameter is read-only to all but the Master MGC.

   ServiceChange may only be applied to a Termination or set of
   Terminations partitioned to the Virtual MG or created (in the case of
   ephemeral Terminations) by that Virtual MG.

   11.2       IG1100    Corrected "Transaction Accept" to "Transaction
                        Reply".

11.3  Negotiation of protocol version

   The first ServiceChange command from a MG shall contain the version
   number of the protocol supported by the MG in the
   ServiceChangeVersion parameter.  Upon receiving such a message, if
   the MGC supports only a lower version, then the MGC shall send a

   ServiceChangeReply with the lower version and thereafter all the
   messages between MG and MGC shall conform to the lower version of the
   protocol.  If the MG is unable to comply and it has established a
   transport connection to the MGC, it should close that connection.  In
   any event, it should reject all subsequent requests from the MGC with
   error 406 - Version Not Supported.

   If the MGC supports a higher version than the MG but is able to
   support the lower version proposed by the MG, it shall send a
   ServiceChangeReply with the lower version and thereafter all the
   messages between MG and MGC shall conform to the lower version of the
   protocol.  If the MGC is unable to comply, it shall reject the
   association, with error 406 - Version Not Supported.

   Protocol version negotiation may also occur at "handoff" and
   "failover" ServiceChanges.

   When extending the protocol with new versions, the following rules
   should be followed:

   1) Existing protocol elements, i.e., procedures, parameters,
      descriptor, property, values, should not be changed unless a
      protocol error needs to be corrected or it becomes necessary to
      change the operation of the service that is being supported by the
      protocol.

   2) The semantics of a command, a parameter, a descriptor, a property,
      or a value should not be changed.

   3) Established rules for formatting and encoding messages and
      parameters should not be modified.

   4) When information elements are found to be obsolete they can be
      marked as not used.  However, the identifier for that information
      element will be marked as reserved.  In that way it can not be
      used in future versions.

   11.4       IG0601    Noted that support of redundant MGs requires
              GEN0202   use of a reliable transport and support in the
                        MGC.  Added more explanation in Geneva.

   11.5       GEN0202   Changed text on replies to transactions in
                        progress during handoff.  Replies now
                        discarded when the service relationship with
                        the old MGC has ended, rather than sent to the
                        new MGC.  The new MGC could still send replies
                        to requests sent to the old MGC.

12 Package definition

   The primary mechanism for extension is by means of Packages.
   Packages define additional Properties, Events, Signals and Statistics
   that may occur on Terminations.

   Packages defined by IETF will appear in separate RFCs.

   Packages defined by ITU-T may appear in the relevant Recommendations
   (e.g., as Recommendations of the H.248 sub-series).

   1) A public document or a standard forum document, which can be
      referenced as the document that describes the package following
      the guideline above, should be specified.

   2) The document shall specify the version of the Package that it
      describes.

   3) The document should be available on a public web server and should
      have a stable URL.  The site should provide a mechanism to provide
      comments and appropriate responses should be returned.

12.1  Guidelines for defining packages

   Packages define Properties, Events, Signals, and Statistics.

   Packages may also define new error codes according to the guidelines
   given in 13.2.  This is a matter of documentary convenience: the
   package documentation is submitted to IANA in support of the error
   code registration.  If a package is modified, it is unnecessary to
   provide IANA with a new document reference in support of the error
   code unless the description of the error code itself is modified.

   Names of all such defined constructs shall consist of the PackageID
   (which uniquely identifies the package) and the ID of the item (which
   uniquely identifies the item in that package).  In the text encoding
   the two shall be separated by a forward slash ("/") character.
   Example: togen/playtone is the text encoding to refer to the play
   tone signal in the tone generation package.

   A Package will contain the following sections:

   12.1.1     IG1100    Made prohibition on overloading of identifiers
                        in extended packages transitive through all
                        ancestors of the extended package.

   12.1.2     GEN0202   Provided requirements for content of the
                        "Possible Values" template item, including
                        specification of default values or behaviour.

12.1.3   Events

   Events defined by the package, specifying:

      Event name: only descriptive

      EventID: is an identifier

      Description:

      EventsDescriptor Parameters:

         Parameters used by the MGC to configure the event, and found in
         the EventsDescriptor.  See 12.2.

      ObservedEventsDescriptor Parameters:

         Parameters returned to the MGC in Notify requests and in
         replies to command requests from the MGC that audit
         ObservedEventsDescriptor, and found in the
         ObservedEventsDescriptor.  See 12.2.

   12.1.4     GEN0202   Added requirement to specify the default
                        signal type, and specify a default duration
                        for TO signals.  Also noted that duration is
                        meaningless for BR, and that the signal type
                        might be dependent on the values of other
                        signal parameters.

   12.2       GEN0202   Fixed section title (covers only event and
                        signal parameters, not properties or
                        statistics).

   12.2       IG1100    Reserved SPA and EPA prefixes, so they are not
                        to be used for signal and event parameter
                        tokens.

   12.2       IG0601    Expanded list of reserved prefixes.

   12.2        IGDUB    Clarified the set of types allowed for signal
                        and event parameters.

   12.2       GEN0202   Added requirement to specify the base type of
                        a sub-list.

   12.2       GEN0202   Provided requirements for content of the
                        "Possible Values" template item, including
                        specification of default values or behaviour.

   12.4        IGDUB    Corrected to indicate identifiers must start
                        with alphabetic rather than alphanumeric
                        character.

   13.1       IG0601    Changed private range of binary package
                        identifiers to convenient hex values.

   A          GEN0202   Removed versions from X.680 and X.690
                        references.

   A.2         IGDUB    Added note warning that the syntax alone does
                        not provide a complete description of the
                        constraints, but must be supplemented by a
                        reading of the text and comments.

   A.2        IG0601    Added description of double wrapping of
                        parameters declared as OCTET STRING.

   A.2        GEN0202   Some editing of double wrapping description to
                        use ASN.1, BER in their proper places.  Added
                        possibility of encoding strings as UTF8String,
                        but only if they contain non-ASCII characters.

   A.2         IGDUB    Added line in table on double wrapping of true
                        octet strings.

   A.2        IG1100    Corrected and expanded comments describing
                        mtpAddress form of MId.  Fixed maximum length
                        of mtpAddress both here and in
                        ServiceChangeAddress.

   A.2        IG0601   Inserted missing lines in IP4Address
                        production.

   A.2        IG0601    Modified TransactionResponseAck to allow
                        acknowledgement of multiple ranges of
                        transactionIds.

   A.2        IG0601    Corrected numerical value of CHOOSE as a
                        context identifier.

   A.2         IGDUB    Added missing extension marker in
                        TopologyRequest.

   A.2        IG1100    AuditReply and AuditResult modified to bring
                        binary functionality into line with text
                        functionality.

   A.2        IG0601    Removed OPTIONAL tag from terminationID in
                        NotifyReply.

   A.2        IG0601    Added extraInfo substructure to EventParameter
                        and SigParameter.

   A.2        IG0601    Modified MediaDescriptor to make it optional
                        to specify a stream.

   A.2        IG0601    Added OPTIONAL tags to reserveValue and
                        reserveGroup.

   A.2         IGDUB    Added to comments for pkgdName to indicate
                        applicability to event names, signal names,
                        and statisticIds as well as property.

   A.2        IG0601    RequestID made optional in EventsDescriptor
                        and SecondEventsDescriptor and comment added
                        saying it must be present if events are
                        present.

   A.2        IG1100    Added OPTIONAL tags on RequestActions and
                        SecondRequestedActions keepActive BOOLEANs.

   A.2        IG1100    Added comment to indicate requestID value to
                        use in an AuditCapReply.

   A.2        GEN0202   Added comment to DigitMapValue indicating time
                        units for timers.

   A.2        IG0601    Added comment indicating coding of Value for
              GEN0202   ServiceChangeReason.  Cleaned up in Geneva to
                        use ASN.1 and BER in their proper places.

   A.2        IG0601    Inserted missing extension marker in
                        ServiceChangeParm production.

   A.2        IG0601    Aligned definition of mtpAddress in
                        ServiceChangeAddress with that in MId.

   A.2        IG0601    Added timestamp to ServiceChangeResParm.

   A.2         IGDUB    Changed type of profileName in
                        ServiceChangeProfile to IA5String.

   A.2        IG0601    Made returned value optional in
                        statisticsParameter, to support
                        auditCapability result.

   A.2        GEN0202   Added reference to ISO 8601:1988 for
                        TimeNotation.

   A.2        IG1100    Value production modified to support the
                        sublist parameter type.

   A.3        IG1100    Corrected ABNF for digitStringlisT, replacing
                        "/" with "|".

   A.3        IG1100    Added parentheses to digitMapRange production.

   A.3        IG1100    Replaced more abbreviated syntax for pathName
                        with fuller definition and constraints copied
                        from B.2.

   B.2         IGDUB    Added note warning that the syntax alone does
                        not provide a complete description of the
                        constraints, but must be supplemented by a
                        reading of the text and comments.

   B.2        IG0601    Added note warning that the interpretation of
                        symbols is context-dependent.

   B.2        IG1100    Added comment to indicate case insensitivity
                        of protocol (excepting SDP) and ABNF.

   B.2        IG0601    Expanded upon and capitalized this comment.

   B.2        IG0601    Lengthy note added on the coding of the VALUE
                        construct.

   B.2         IGDUB    Deleted sentence in note suggesting that
                        packages could add new types for properties,
                        parameters, or statistics.

   B.2        IG0601    Added note indicating that parsers should
                        allow for white space preceding the first line
                        of SDP in Local or Remote.

   B.2         IGDUB    Added comments identifying the O- and W- tags.

   B.2        IG1100    Moved wildcard tag up from individual commands
                        to commandRequestList.

   B.2        GEN0202   Added additional error case to actionReply.

   B.2        IG0601    Modified syntax of auditOther to allow return
                        of terminationID only.

   B.2         IGDUB    Corrected upper limit for V4hex.

   B.2        IG1100    Corrected and expanded comments describing
                        mtpAddress form of MId.

   B.2        IG0601    Modified comment to mediaParm to make
                        streamParms and StreamDescriptor mutually
                        exclusive.

   B.2        GEN0202   Modified comment further to indicate at most
                        one instance of terminationStateDescriptor.

   B.2        GEN0202   Expanded comment for streamParm to indicate
                        the restriction on repetition is per item.

   B.2        IG0601    Modified "at most once" comments to localParm,
                        terminationStateParm, and modemType, to allow
                        multiple instances of propertyParm in the
                        first two cases and extensionParameter in the
                        last one.

   B.2        IG0601    Added note before description of Local and
                        Remote, pointing out that the octet value x00
                        is not allowed in octetString.

   B.2        IG0601    Syntax for eventsDescriptor, embedFirst, and
                        eventBufferDescriptor modified to make
                        contents beyond token optional.

   B.2         IGDUB    Replaced "event" by "item" in comment to
                        pkgdName because pkgdName applies to
                        properties, signals, and statistics as well.

   B.2        IG0601    Corrected placement of EQUAL in eventDM
                        production.

   B.2        IG1100    Added comment and syntax to indicate requestID
                        value to use in an AuditCapReply.

   B.2        IG1100    Corrected Modem Descriptor to allow package
                        items as properties.

   B.2        IG0601    Comment to modemType changed to allow multiple
                        instances of extensionParameter.

   B.2        GEN0202   Comment added to indicate units for Timer.

   B.2        IG1100    Added parentheses to digitMapRange production.

   B.2        IG1100    Added comment to serviceChangeParm,
                        restricting each parameter to one appearance.

   B.2        IG0601    Added comments making serviceChangeMgcId and
                        serviceChangeAddress mutually exclusive in
                        ServiceChangeParm and servChgReplyParm.

   B.2         IGDUB    Added comment to serviceChangeParm indicating
                        that ServiceChangeMethod and
                        ServiceChangeReason are required.

   B.2        IG0601    Added Timestamp to servChgReplyParm.

   B.2        IG0601    Added comment indicating coding of Value for
                        ServiceChangeReason.

   B.2        IG0601    Modified ServiceChangeAddress to use MId
                        definition for full address.

   B.2        IG1100    Made returned value optional in
                        statisticsParameter, to support
                        auditCapability result.

   B.2        IG1100    Changed topologyDescriptor to allow multiple
                        triples.

   B.2        IG0601    Added comment forbidding use of a double quote
                        within a quotedString value.

   B.2        IG1100    Reserved prefixes for new tokens added to
                        signalParameter and eventParameter, to avoid
                        collision with package names.

   B.2        IG1100    EmbedToken and EmergencyToken changed to
                        remove clash with EventBufferToken.

   B.3        IG1100    New section describing hexadecimal octet
                        encoding.

   B.4        IG1100    New section describing hex octet sequence.

   C          IG1100    Added permission to use Annex C properties in
                        LocalControl as well as in Local and Remote.

   C          IG0601    Added text making support of all properties of
                        Annex C optional.

   C           IGDUB    Added directions to reconcile tabulated
                        formats with allowed types for properties.

   C.1        IG1100    Corrected Q.765 reference to Q.765.5 for
                        ACodec.

   C.1        IG1100    Deprecated Echocanc codepoint in favour of
                        package-defined property.

   C.4        ITUPOST   Updated references from Q.2961 to Q.2961.1.

   C.4         IGDUB    Added details on format of VPVC.

   C.9        IG1100    Renamed USI to layer1prot.

   C.9        IG1100    Deprecated ECHOCI codepoint in favour of
                        package-defined property.

   C.9        IG1100    Added new USI property.

   C.11       IG1100    Added m= line tag.

   D.1        IG0601    Added explanation of ALF.

   D.1.5       IGDUB    Expanded text indicating that when trying to
                        reestablish contact with the previously
                        controlling MGC the MG uses the Disconnected
                        method.

   E.1.2      GEN0202   Added missing EventsDescriptor parameters
                        lines.

   E.1.2      GEN0202   For the Signal Completion event:
                        - corrected the description of how it is
                        enabled
                        - heavily edited the description of the Signal
                        Identity observed event parameter and added a
                        type.

   E.1.2       IGDUB    The timeout completion reason for the Signal
                        Completion event was broadened to include
                        other circumstances where the signal completed
                        on its own.

   E.1.2      IG1100    Added signal list ID observed event parameter
                        to the Signal Completion event.

   E.2.1      IG0601    Added missing read only, read-write
                        specifications.

   E.2.1      IG0601    Split ProvisionalResponseTimer properties into
                        one for MG, one for MGC.

   E.3        GEN0202   Added "Designed to be extended only" to
                        tonegen package description.

   E.4        GEN0202   Added "Designed to be extended only" to
                        tonedet package description.

   E.4.2      GEN0202   Added type for tone ID observed parameter for
                        Long Tone Detected event.

   E.6.2      IG1100    Corrected binary identifier for digit map
                        completion event to avoid clash with base
                        package.

   E.6.2      IG1100    Removed procedural text.

   E.6.5      IG1100    Added procedural text indicating where to find
                        the applicable digit map and indicating the
                        error to return if the parameter is missing.

   E.6.5      IG0601    Further modified procedural text.

   E.7.3      IG1100    Corrected text identifier for payphone
                        recognition tone to avoid clash with base
                        package.

   E.10.5      IGDUB    Provided informative references for tones and
                        procedures for continuity check.

12.1.5   Statistics

   Statistics defined by the package, specifying:

      Statistic name: only descriptive

      StatisticID: is an identifier

      StatisticID is used in a StatisticsDescriptor

      Description:

      Units: unit of measure, e.g., milliseconds, packets

12.1.6   Procedures

   Additional guidance on the use of the package.

12.2  Guidelines to defining Parameters to Events and Signals

   Parameter Name: only descriptive

   ParameterID: is an identifier.  The textual ParameterID of parameters
   to Events and Signals shall not start with "EPA" and "SPA",
   respectively.  The textual ParameterID shall also not be "ST",
   "Stream", "SY", "SignalType", "DR", "Duration", "NC",
   "NotifyCompletion", "KA", "Keepactive", "EB", "Embed", "DM" or
   "DigitMap".

   Type: One of:

      Boolean

      String: UTF-8 octet string

      Octet String: A number of octets.  See Annex A and Annex B.3 for
      encoding

      Integer: 4-octet signed integer

      Double: 8-octet signed integer

      Character: unicode UTF-8 encoding of a single letter.  Could be
      more than one octet.

      Enumeration: one of a list of possible unique values (see 12.3)

      Sub-list: a list of several values from a list (not supported for
      statistics).  The type of sub-list SHALL also be specified.  The
      type shall be chosen from the types specified in this section
      (with the exception of sub-list).  For example, Type: sub-list of
      enumeration.  The encoding of sub-lists is specified in Annexes A
      and B.3.

   Possible values:

      A package MUST specify either a specific set of values or a
      description of how values are determined.  A package MUST also
      specify a default value or the default behavior when the value is
      omitted from its descriptor.  For example, a package may specify
      that procedures related to the parameter are suspended when it
      value is omitted.  A default value (but not procedures) may be
      specified as provisionable.

   Description:

12.3  Lists

   Possible values for parameters include enumerations.  Enumerations
   may be defined in a list.  It is recommended that the list be IANA
   registered so that packages that extend the list can be defined
   without concern for conflicting names.

12.4  Identifiers

   Identifiers in text encoding shall be strings of up to 64 characters,
   containing no spaces, starting with an alphabetic character and
   consisting of alphanumeric characters and/or digits, and possibly
   including the special character underscore ("_").

   Identifiers in binary encoding are 2 octets long.

   Both text and binary values shall be specified for each identifier,
   including identifiers used as values in enumerated types.

12.5  Package registration

   A package can be registered with IANA for interoperability reasons.
   See clause 13 for IANA Considerations.

13 IANA Considerations

13.1  Packages

   The following considerations SHALL be met to register a package with
   IANA:

   1) A unique string name, unique serial number and version number is
      registered for each package.  The string name is used with text
      encoding.  The serial number shall be used with binary encoding.
      Serial Numbers 0x8000 to 0xFFFF are reserved for private use.
      Serial number 0 is reserved.

   2) A contact name, email and postal addresses for that contact shall
      be specified.  The contact information shall be updated by the
      defining organization as necessary.

   3) A reference to a document that describes the package, which should
      be public:

      The document shall specify the version of the Package that it
      describes.

      If the document is public, it should be located on a public web
      server and should have a stable URL.  The site should provide a
      mechanism to provide comments and appropriate responses should be
      returned.

   4) Packages registered by other than recognized standards bodies
      shall have a minimum package name length of 8 characters.

   5) All other package names are first come-first served if all other
      conditions are met.

13.2  Error codes

   The following considerations SHALL be met to register an error code
   with IANA:

   1) An error number and a one-line (80-character maximum) string is
      registered for each error.

   2) A complete description of the conditions under which the error is
      detected shall be included in a publicly available document.  The
      description shall be sufficiently clear to differentiate the error
      from all other existing error codes.

   3) The document should be available on a public web server and should
      have a stable URL.

   4) Error numbers registered by recognized standards bodies shall have
      3- or 4-character error numbers.

   5) Error numbers registered by all other organizations or individuals
      shall have 4-character error numbers.

   6) An error number shall not be redefined nor modified except by the
      organization or individual that originally defined it, or their
      successors or assigns.

13.3  ServiceChange reasons

   The following considerations SHALL be met to register service change
   reason with IANA:

   1) A one-phrase, 80-character maximum, unique reason code is
      registered for each reason.

   2) A complete description of the conditions under which the reason is
      used is detected shall be included in a publicly available
      document.  The description shall be sufficiently clear to
      differentiate the reason from all other existing reasons.

   3) The document should be available on a public web server and should
      have a stable URL.

ANNEX A - Binary encoding of the protocol

   This annex specifies the syntax of messages using the notation
   defined in Recommendation X.680; Information technology - Abstract
   Syntax Notation One (ASN.1): Specification of basic notation.
   Messages shall be encoded for transmission by applying the basic
   encoding rules specified in Recommendation X.690, Information
   Technology - ASN.1 Encoding Rules: Specification of Basic Encoding
   Rules (BER), Canonical Encoding Rules (CER) and Distinguished
   Encoding Rules.

A.1   Coding of wildcards

   The use of wildcards ALL and CHOOSE is allowed in the protocol.  This
   allows a MGC to partially specify Termination IDs and to let the MG
   choose from the values that conform to the partial specification.
   Termination IDs may encode a hierarchy of names.  This hierarchy is
   provisioned.  For instance, a TerminationID may consist of a trunk
   group, a trunk within the group and a circuit.  Wildcarding must be
   possible at all levels.  The following paragraphs explain how this is
   achieved.

   The ASN.1 description uses octet strings of up to 8 octets in length
   for Termination IDs.  This means that Termination IDs consist of at
   most 64 bits.  A fully specified Termination ID may be preceded by a
   sequence of wildcarding fields.  A wildcarding field is one octet in
   length.  Bit 7 (the most significant bit) of this octet specifies
   what type of wildcarding is invoked: if the bit value equals 1, then
   the ALL wildcard is used; if the bit value if 0, then the CHOOSE
   wildcard is used.  Bit 6 of the wildcarding field specifies whether
   the wildcarding pertains to one level in the hierarchical naming
   scheme (bit value 0) or to the level of the hierarchy specified in
   the wildcarding field plus all lower levels (bit value 1).  Bits 0
   through 5 of the wildcarding field specify the bit position in the
   Termination ID at which the wildcarding starts.

   We illustrate this scheme with some examples.  In these examples, the
   most significant bit in a string of bits appears on the left hand
   side.

   Assume that Termination IDs are three octets long and that each octet
   represents a level in a hierarchical naming scheme.  A valid
   Termination ID is:

      00000001 00011110 01010101.

   Addressing ALL names with prefix 00000001 00011110 is done as
   follows:

      wildcarding field: 10000111

      Termination ID: 00000001 00011110 xxxxxxxx.

   The values of the bits labeled "x" is irrelevant and shall be ignored
   by the receiver.

   Indicating to the receiver that it must choose a name with 00011110
   as the second octet is done as follows:

      wildcarding fields: 00010111 followed by 00000111

      Termination ID: xxxxxxxx 00011110 xxxxxxxx.

   The first wildcard field indicates a CHOOSE wildcard for the level in
   the naming hierarchy starting at bit 23, the highest level in our
   assumed naming scheme.  The second wildcard field indicates a CHOOSE
   wildcard for the level in the naming hierarchy starting at bit 7, the
   lowest level in our assumed naming scheme.

   Finally, a CHOOSE-wildcarded name with the highest level of the name
   equal to 00000001 is specified as follows:

      wildcard field: 01001111

      Termination ID: 0000001 xxxxxxxx xxxxxxxx .

   Bit value 1 at bit position 6 of the first octet of the wildcard
   field indicates that the wildcarding pertains to the specified level
   in the naming hierarchy and all lower levels.

   Context IDs may also be wildcarded.  In the case of Context IDs,
   however, specifying partial names is not allowed.  Context ID 0x0
   SHALL be used to indicate the NULL Context, Context ID 0xFFFFFFFE
   SHALL be used to indicate a CHOOSE wildcard, and Context ID
   0xFFFFFFFF SHALL be used to indicate an ALL wildcard.

   TerminationID 0xFFFFFFFFFFFFFFFF SHALL be used to indicate the ROOT
   Termination.

A.2   ASN.1 syntax specification

   This subclause contains the ASN.1 specification of the H.248.1
   protocol syntax.

     NOTE 1 - In case a transport mechanism is used that employs
     application level framing, the definition of Transaction below
     changes.  Refer to the annex or to the Recommendation of the H.248
     sub-series defining the transport mechanism for the definition that
     applies in that case.

     NOTE 2 - The ASN.1 specification below contains a clause defining
     TerminationIDList as a sequence of TerminationIDs.  The length of
     this sequence SHALL be one, except possibly when used in
     contextAuditResult.

     NOTE 3 - This syntax specification does not enforce all
     restrictions on element inclusions and values.  Some additional
     restrictions are stated in comments and other restrictions appear
     in the text of this RFC.  These additional restrictions
     are part of the protocol even though not enforced by this
     specification.

     NOTE 4 - The ASN.1 module in this Annex uses octet string types to
     encode values for property parameter, signal parameter and event
     parameter values and statistics.  The actual types of these values
     vary and are specified in Annex C or the relevant package
     definition.

   A value is first BER-encoded based on its type using the table below.
   The result of this BER-encoding is then encoded as an ASN.1 octet
   string, "double wrapping" the value.  The format specified in Annex C
   or the package relates to BER encoding according to the following
   table:

   Type Specified in Package   ASN.1 BER Type

   String                      IA5String or UTF8String (Note 4)

   Integer (4 Octet)           INTEGER

   Double (8 octet signed int) INTEGER (Note 3)

   Character (UTF-8, Note 1)   IA5String

   Enumeration                 ENUMERATED

   Boolean                     BOOLEAN

   Unsigned Integer (Note 2)   INTEGER  (Note 3)

   Octet (String)              OCTET STRING

     Note 1: Can be more than one byte

     Note 2: Unsigned integer is referenced in Annex C

     Note 3: The BER encoding of INTEGER does not imply the use of 4
     bytes.

     Note 4: String should be encoded as IA5String when the contents
     are all ASCII characters, but as UTF8String if it contains any
     Non-ASCII characters.

   See ITU-T Rec.  X.690, 8.7, for the definition of the encoding of an
   octet string value.

   MEDIA-GATEWAY-CONTROL DEFINITIONS AUTOMATIC TAGS::=
   BEGIN

   MegacoMessage ::= SEQUENCE
   {
      authHeader     AuthenticationHeader OPTIONAL,
      mess           Message
   }

   AuthenticationHeader ::= SEQUENCE
   {
      secParmIndex   SecurityParmIndex,
      seqNum         SequenceNum,
      ad             AuthData
   }

   SecurityParmIndex ::= OCTET STRING(SIZE(4))

   SequenceNum       ::= OCTET STRING(SIZE(4))

   AuthData          ::= OCTET STRING (SIZE (12..32))

   Message ::= SEQUENCE
   {
      version           INTEGER(0..99),
      -- The version of the protocol defined here is equal to 1.
      mId               MId,  -- Name/address of message originator
      messageBody       CHOICE
      {
         messageError      ErrorDescriptor,
         transactions      SEQUENCE OF Transaction
      },
      ...
   }

   MId ::= CHOICE
   {
      ip4Address           IP4Address,
      ip6Address           IP6Address,
      domainName           DomainName,
      deviceName           PathName,
      mtpAddress           OCTET STRING(SIZE(2..4)),
      -- Addressing structure of mtpAddress:
      --     25 - 15           0
      --        |  PC        | NI |
      --      24 - 14 bits    2 bits
      -- Note: 14 bits are defined for international use.
      -- Two national options exist where the point code is 16 or 24
      -- bits.
      -- To octet align the mtpAddress, the MSBs shall be encoded as 0s.
             ...
   }

   DomainName ::= SEQUENCE
   {
      name        IA5String,
      -- The name starts with an alphanumeric digit followed by a
      -- sequence of alphanumeric digits, hyphens and dots.  No two
      -- dots shall occur consecutively.
      portNumber     INTEGER(0..65535) OPTIONAL
   }

   IP4Address ::= SEQUENCE
   {
      address        OCTET STRING (SIZE(4)),
      portNumber     INTEGER(0..65535) OPTIONAL
   }

   IP6Address ::= SEQUENCE
   {
      address        OCTET STRING (SIZE(16)),
      portNumber     INTEGER(0..65535) OPTIONAL
   }

   PathName ::= IA5String(SIZE (1..64))
   -- See A.3

   Transaction ::= CHOICE

   {
      transactionRequest   TransactionRequest,
      transactionPending   TransactionPending,
      transactionReply     TransactionReply,
      transactionResponseAck  TransactionResponseAck,
          -- use of response acks is dependent on underlying transport
      ...
   }

   TransactionId ::= INTEGER(0..4294967295)  -- 32-bit unsigned integer

   TransactionRequest ::= SEQUENCE
   {
      transactionId        TransactionId,
      actions              SEQUENCE OF ActionRequest,
      ...
   }

   TransactionPending ::= SEQUENCE
   {
      transactionId        TransactionId,
      ...
   }

   TransactionReply ::= SEQUENCE
   {
      transactionId        TransactionId,
      immAckRequired       NULL OPTIONAL,
      transactionResult    CHOICE
      {
           transactionError   ErrorDescriptor,
           actionReplies      SEQUENCE OF ActionReply
      },
      ...
   }

   TransactionResponseAck ::= SEQUENCE OF TransactionAck
   TransactionAck ::= SEQUENCE
   {
      firstAck       TransactionId,
      lastAck        TransactionId OPTIONAL
   }

   ErrorDescriptor ::= SEQUENCE
   {
      errorCode      ErrorCode,
      errorText      ErrorText OPTIONAL
   }

   ErrorCode ::= INTEGER(0..65535)
   -- See clause 13 for IANA Considerations with respect to error codes

   ErrorText ::= IA5String

   ContextID ::= INTEGER(0..4294967295)

   -- Context   NULL Value: 0
   -- Context CHOOSE Value: 4294967294 (0xFFFFFFFE)
   -- Context    ALL Value: 4294967295 (0xFFFFFFFF)


   ActionRequest ::= SEQUENCE
   {
      contextId         ContextID,
      contextRequest       ContextRequest OPTIONAL,
      contextAttrAuditReq  ContextAttrAuditRequest OPTIONAL,
      commandRequests   SEQUENCE OF CommandRequest
   }

   ActionReply ::= SEQUENCE
   {
      contextId         ContextID,
      errorDescriptor   ErrorDescriptor OPTIONAL,
      contextReply      ContextRequest OPTIONAL,
      commandReply      SEQUENCE OF CommandReply
   }

   ContextRequest ::= SEQUENCE
   {
      priority       INTEGER(0..15) OPTIONAL,
      emergency      BOOLEAN OPTIONAL,
      topologyReq    SEQUENCE OF TopologyRequest OPTIONAL,
      ...
   }

   ContextAttrAuditRequest ::= SEQUENCE
   {
      topology    NULL OPTIONAL,
      emergency   NULL OPTIONAL,
      priority    NULL OPTIONAL,
      ...
   }

   CommandRequest ::= SEQUENCE
   {
      command           Command,
      optional          NULL OPTIONAL,
      wildcardReturn    NULL OPTIONAL,
      ...
   }

   Command ::= CHOICE
   {
      addReq               AmmRequest,
      moveReq              AmmRequest,
      modReq               AmmRequest,
      -- Add, Move, Modify requests have the same parameters
      subtractReq          SubtractRequest,
      auditCapRequest      AuditRequest,
      auditValueRequest    AuditRequest,
      notifyReq            NotifyRequest,
      serviceChangeReq     ServiceChangeRequest,
      ...
   }

   CommandReply ::= CHOICE
   {
      addReply                AmmsReply,
      moveReply               AmmsReply,
      modReply                AmmsReply,
      subtractReply           AmmsReply,
      -- Add, Move, Modify, Subtract replies have the same parameters
      auditCapReply           AuditReply,
      auditValueReply         AuditReply,
      notifyReply             NotifyReply,
      serviceChangeReply      ServiceChangeReply,
      ...
   }

   TopologyRequest ::= SEQUENCE
   {
      terminationFrom         TerminationID,
      terminationTo           TerminationID,
      topologyDirection       ENUMERATED
      {
         bothway(0),
         isolate(1),
         oneway(2)
      },
      ...
   }

   AmmRequest ::= SEQUENCE
   {

      terminationID        TerminationIDList,
      descriptors          SEQUENCE OF AmmDescriptor,
      -- At most one descriptor of each type (see AmmDescriptor)
      -- allowed in the sequence.
      ...
   }

   AmmDescriptor ::= CHOICE
   {
      mediaDescriptor         MediaDescriptor,
      modemDescriptor         ModemDescriptor,
      muxDescriptor           MuxDescriptor,
      eventsDescriptor        EventsDescriptor,
      eventBufferDescriptor   EventBufferDescriptor,
      signalsDescriptor       SignalsDescriptor,
      digitMapDescriptor      DigitMapDescriptor,
      auditDescriptor         AuditDescriptor,
      ...
   }

   AmmsReply ::= SEQUENCE
   {
      terminationID        TerminationIDList,
      terminationAudit     TerminationAudit OPTIONAL,
      ...
   }

   SubtractRequest ::= SEQUENCE
   {
      terminationID        TerminationIDList,
      auditDescriptor      AuditDescriptor OPTIONAL,
      ...
   }

   AuditRequest ::= SEQUENCE
   {
      terminationID        TerminationID,
      auditDescriptor      AuditDescriptor,
      ...
   }

   AuditReply ::= CHOICE
   {
      contextAuditResult   TerminationIDList,
      error                ErrorDescriptor,
      auditResult          AuditResult,
      ...
   }

   AuditResult ::= SEQUENCE
   {

      terminationID           TerminationID,
      terminationAuditResult  TerminationAudit
   }

   TerminationAudit ::= SEQUENCE OF AuditReturnParameter

   AuditReturnParameter ::= CHOICE
   {
      errorDescriptor         ErrorDescriptor,
      mediaDescriptor         MediaDescriptor,
      modemDescriptor         ModemDescriptor,
      muxDescriptor           MuxDescriptor,
      eventsDescriptor        EventsDescriptor,
      eventBufferDescriptor   EventBufferDescriptor,
      signalsDescriptor       SignalsDescriptor,
      digitMapDescriptor      DigitMapDescriptor,
      observedEventsDescriptor   ObservedEventsDescriptor,
      statisticsDescriptor    StatisticsDescriptor,
      packagesDescriptor      PackagesDescriptor,
      emptyDescriptors        AuditDescriptor,
      ...
   }

   AuditDescriptor ::= SEQUENCE
   {
      auditToken  BIT STRING
         {
            muxToken(0), modemToken(1), mediaToken(2),
            eventsToken(3), signalsToken(4),
            digitMapToken(5), statsToken(6),
            observedEventsToken(7),
            packagesToken(8), eventBufferToken(9)
         } OPTIONAL,
      ...
   }

   NotifyRequest ::= SEQUENCE
   {
      terminationID              TerminationIDList,
      observedEventsDescriptor   ObservedEventsDescriptor,
      errorDescriptor            ErrorDescriptor OPTIONAL,
      ...
   }

   NotifyReply ::= SEQUENCE
   {
      terminationID           TerminationIDList,
      errorDescriptor         ErrorDescriptor OPTIONAL,
      ...
   }

   ObservedEventsDescriptor ::= SEQUENCE
   {
      requestId               RequestID,
      observedEventLst        SEQUENCE OF ObservedEvent
   }

   ObservedEvent ::= SEQUENCE
   {
      eventName            EventName,
      streamID             StreamID OPTIONAL,
      eventParList         SEQUENCE OF EventParameter,
      timeNotation         TimeNotation OPTIONAL,
      ...
   }

   EventName ::= PkgdName

   EventParameter ::= SEQUENCE
   {
      eventParameterName      Name,
      value                   Value,
   -- For use of extraInfo see the comment related to PropertyParm
      extraInfo CHOICE
      {
         relation Relation,
         range    BOOLEAN,
         sublist  BOOLEAN
      } OPTIONAL,
      ...
   }

   ServiceChangeRequest ::= SEQUENCE
   {
      terminationID           TerminationIDList,
      serviceChangeParms      ServiceChangeParm,
      ...
   }

   ServiceChangeReply ::= SEQUENCE
   {
      terminationID           TerminationIDList,
      serviceChangeResult     ServiceChangeResult,
      ...
   }

   -- For ServiceChangeResult, no parameters are mandatory.  Hence the
   -- distinction between ServiceChangeParm and ServiceChangeResParm.

   ServiceChangeResult ::= CHOICE
   {
      errorDescriptor            ErrorDescriptor,
      serviceChangeResParms      ServiceChangeResParm
   }

   WildcardField ::= OCTET STRING(SIZE(1))

   TerminationID ::= SEQUENCE
   {
      wildcard SEQUENCE OF WildcardField,
      id    OCTET STRING(SIZE(1..8)),
      ...
   }
   -- See A.1 for explanation of wildcarding mechanism.
   -- Termination ID 0xFFFFFFFFFFFFFFFF indicates the ROOT Termination.

   TerminationIDList ::= SEQUENCE OF TerminationID

   MediaDescriptor ::= SEQUENCE
   {

      termStateDescr TerminationStateDescriptor OPTIONAL,
      streams     CHOICE
      {
         oneStream      StreamParms,
         multiStream    SEQUENCE OF StreamDescriptor
      } OPTIONAL,
      ...
   }

   StreamDescriptor ::= SEQUENCE
   {
      streamID          StreamID,
      streamParms       StreamParms
   }

   StreamParms ::= SEQUENCE
   {
      localControlDescriptor     LocalControlDescriptor OPTIONAL,
      localDescriptor            LocalRemoteDescriptor OPTIONAL,
      remoteDescriptor           LocalRemoteDescriptor OPTIONAL,
      ...
   }

   LocalControlDescriptor ::= SEQUENCE
   {

      streamMode        StreamMode OPTIONAL,
      reserveValue      BOOLEAN OPTIONAL,
      reserveGroup      BOOLEAN OPTIONAL,
      propertyParms     SEQUENCE OF PropertyParm,
      ...
   }

   StreamMode ::= ENUMERATED
   {
      sendOnly(0),
      recvOnly(1),
      sendRecv(2),
      inactive(3),
      loopBack(4),
         ...
   }

   -- In PropertyParm, value is a SEQUENCE OF octet string.  When sent
   -- by an MGC the interpretation is as follows:
   -- empty sequence means CHOOSE
   -- one element sequence specifies value
   -- If the sublist field is not selected, a longer sequence means
   -- "choose one of the values" (i.e., value1 OR value2 OR ...)
   -- If the sublist field is selected,
   -- a sequence with more than one element encodes the value of a
   -- list-valued property (i.e., value1 AND value2 AND ...).
   -- The relation field may only be selected if the value sequence
   -- has length 1.  It indicates that the MG has to choose a value
   -- for the property.  E.g., x > 3 (using the greaterThan
   -- value for relation) instructs the MG to choose any value larger
   -- than 3 for property x.
   -- The range field may only be selected if the value sequence
   -- has length 2.  It indicates that the MG has to choose a value
   -- in the range between the first octet in the value sequence and
   -- the trailing octet in the value sequence, including the
   -- boundary values.
   -- When sent by the MG, only responses to an AuditCapability request
   -- may contain multiple values, a range, or a relation field.

   PropertyParm ::= SEQUENCE
   {

      name        PkgdName,
      value       SEQUENCE OF OCTET STRING,
      extraInfo   CHOICE
      {
         relation    Relation,
         range       BOOLEAN,
         sublist     BOOLEAN
      } OPTIONAL,
      ...
   }

   Name ::= OCTET STRING(SIZE(2))

   PkgdName ::= OCTET STRING(SIZE(4))
   -- represents Package Name (2 octets) plus Property, Event,
   -- Signal Names or Statistics ID. (2 octets)
   -- To wildcard a package use 0xFFFF for first two octets, choose
   -- is not allowed.  To reference native property tag specified in
   -- Annex C, use 0x0000 as first two octets.
   -- To wildcard a Property, Event, Signal, or Statistics ID, use
   -- 0xFFFF for last two octets, choose is not allowed.
   -- Wildcarding of Package Name is permitted only if Property,
   -- Event, Signal, or Statistics ID are
   -- also wildcarded.

   Relation ::= ENUMERATED
   {
      greaterThan(0),
      smallerThan(1),
      unequalTo(2),
      ...
   }

   LocalRemoteDescriptor ::= SEQUENCE
   {
      propGrps SEQUENCE OF PropertyGroup,
      ...
   }

   PropertyGroup ::= SEQUENCE OF PropertyParm

   TerminationStateDescriptor ::= SEQUENCE
   {
      propertyParms        SEQUENCE OF PropertyParm,
      eventBufferControl   EventBufferControl OPTIONAL,
      serviceState         ServiceState OPTIONAL,
      ...
   }

   EventBufferControl ::= ENUMERATED
   {
      off(0),
      lockStep(1),
      ...
   }

   ServiceState ::= ENUMERATED

   {
      test(0),
      outOfSvc(1),
      inSvc(2),
         ...
   }

   MuxDescriptor   ::= SEQUENCE
   {
      muxType           MuxType,
      termList          SEQUENCE OF TerminationID,
      nonStandardData   NonStandardData OPTIONAL,
      ...
   }

   MuxType ::= ENUMERATED
   {
      h221(0),
      h223(1),
      h226(2),
      v76(3),
      ...
   }

   StreamID ::= INTEGER(0..65535)   -- 16-bit unsigned integer

   EventsDescriptor ::= SEQUENCE
   {
      requestID      RequestID OPTIONAL,
                  -- RequestID must be present if eventList
                  -- is non empty
      eventList      SEQUENCE OF RequestedEvent,
      ...
   }

   RequestedEvent ::= SEQUENCE
   {
      pkgdName       PkgdName,
      streamID       StreamID OPTIONAL,
      eventAction    RequestedActions OPTIONAL,
      evParList      SEQUENCE OF EventParameter,
      ...
   }

   RequestedActions ::= SEQUENCE
   {
      keepActive        BOOLEAN OPTIONAL,
      eventDM           EventDM OPTIONAL,
      secondEvent          SecondEventsDescriptor OPTIONAL,
      signalsDescriptor    SignalsDescriptor OPTIONAL,
      ...
   }

   EventDM ::= CHOICE
   {  digitMapName   DigitMapName,
      digitMapValue  DigitMapValue
   }

   SecondEventsDescriptor ::= SEQUENCE
   {
      requestID         RequestID OPTIONAL,
      eventList         SEQUENCE OF SecondRequestedEvent,
      ...
   }

   SecondRequestedEvent ::= SEQUENCE
   {
      pkgdName          PkgdName,
      streamID          StreamID OPTIONAL,
      eventAction       SecondRequestedActions OPTIONAL,
      evParList         SEQUENCE OF EventParameter,
      ...
   }

   SecondRequestedActions ::= SEQUENCE
   {
      keepActive           BOOLEAN OPTIONAL,
      eventDM              EventDM OPTIONAL,
      signalsDescriptor    SignalsDescriptor OPTIONAL,
      ...
   }

   EventBufferDescriptor ::= SEQUENCE OF EventSpec

   EventSpec ::= SEQUENCE
   {

      eventName      EventName,
      streamID       StreamID OPTIONAL,
      eventParList   SEQUENCE OF EventParameter,
      ...
   }

   SignalsDescriptor ::= SEQUENCE OF SignalRequest

   SignalRequest ::=CHOICE
   {
      signal         Signal,
      seqSigList     SeqSigList,
      ...
   }

   SeqSigList ::= SEQUENCE
   {
      id                INTEGER(0..65535),
      signalList        SEQUENCE OF Signal
   }

   Signal ::= SEQUENCE
   {
      signalName        SignalName,
      streamID          StreamID OPTIONAL,
      sigType           SignalType OPTIONAL,
      duration          INTEGER (0..65535) OPTIONAL,
      notifyCompletion  NotifyCompletion OPTIONAL,
      keepActive        BOOLEAN OPTIONAL,
      sigParList        SEQUENCE OF SigParameter,
      ...
   }

   SignalType ::= ENUMERATED
   {
      brief(0),
      onOff(1),
      timeOut(2),
      ...
   }

   SignalName ::= PkgdName

   NotifyCompletion ::= BIT STRING
   {
      onTimeOut(0), onInterruptByEvent(1),
      onInterruptByNewSignalDescr(2), otherReason(3)
   }

   SigParameter ::= SEQUENCE
   {
      sigParameterName     Name,
      value                Value,
      -- For use of extraInfo see the comment related to PropertyParm
      extraInfo CHOICE
      {
         relation Relation,
         range    BOOLEAN,
         sublist  BOOLEAN

      } OPTIONAL,
      ...
   }

   -- For an AuditCapReply with all events, the RequestID SHALL be ALL.
   -- ALL is represented by 0xffffffff.

   RequestID ::= INTEGER(0..4294967295)   -- 32-bit unsigned integer

   ModemDescriptor ::= SEQUENCE
   {
      mtl               SEQUENCE OF ModemType,
      mpl               SEQUENCE OF PropertyParm,
      nonStandardData   NonStandardData OPTIONAL
   }

   ModemType ::= ENUMERATED
   {
      v18(0),
      v22(1),
      v22bis(2),
      v32(3),
      v32bis(4),
      v34(5),
      v90(6),
      v91(7),
      synchISDN(8),
      ...
   }

   DigitMapDescriptor ::= SEQUENCE
   {
      digitMapName   DigitMapName   OPTIONAL,
      digitMapValue  DigitMapValue  OPTIONAL
   }

   DigitMapName ::= Name

   DigitMapValue ::= SEQUENCE
   {
      startTimer     INTEGER(0..99) OPTIONAL,
      shortTimer     INTEGER(0..99) OPTIONAL,
      longTimer      INTEGER(0..99) OPTIONAL,
      digitMapBody      IA5String,
   -- Units are seconds for start, short and long timers, and
   -- hundreds of milliseconds for duration timer.  Thus start,
   -- short, and long range from 1 to 99 seconds and duration
   -- from 100 ms to 9.9 s
      -- See A.3 for explanation of digit map syntax
      ...
   }

   ServiceChangeParm ::= SEQUENCE
   {
      serviceChangeMethod     ServiceChangeMethod,
      serviceChangeAddress    ServiceChangeAddress OPTIONAL,
      serviceChangeVersion    INTEGER(0..99) OPTIONAL,
      serviceChangeProfile    ServiceChangeProfile OPTIONAL,
      serviceChangeReason     Value,
   -- A serviceChangeReason consists of a numeric reason code
   -- and an optional text description.
   -- The serviceChangeReason SHALL be a string consisting of
   -- a decimal reason code, optionally followed by a single
   -- space character and a textual description string.
   -- This string is first BER-encoded as an IA5String.
   -- The result of this BER-encoding is then encoded as
   -- an ASN.1 OCTET STRING type, "double wrapping" the
   -- value as was done for package elements.
      serviceChangeDelay      INTEGER(0..4294967295) OPTIONAL,
                                        -- 32-bit unsigned integer
      serviceChangeMgcId      MId OPTIONAL,
      timeStamp               TimeNotation OPTIONAL,
      nonStandardData         NonStandardData OPTIONAL,
      ...
   }

   ServiceChangeAddress ::= CHOICE
   {
      portNumber        INTEGER(0..65535),    -- TCP/UDP port number
      ip4Address        IP4Address,
      ip6Address        IP6Address,
      domainName        DomainName,
      deviceName        PathName,
      mtpAddress        OCTET STRING(SIZE(2..4)),
      ...
   }

   ServiceChangeResParm ::= SEQUENCE
   {
      serviceChangeMgcId      MId OPTIONAL,
      serviceChangeAddress    ServiceChangeAddress OPTIONAL,
      serviceChangeVersion    INTEGER(0..99) OPTIONAL,
      serviceChangeProfile    ServiceChangeProfile OPTIONAL,
      timestamp               TimeNotation OPTIONAL,
      ...
   }

   ServiceChangeMethod ::= ENUMERATED

   {
      failover(0),
      forced(1),
      graceful(2),
      restart(3),
      disconnected(4),
      handOff(5),
      ...
   }

   ServiceChangeProfile ::= SEQUENCE
   {
      profileName    IA5String(SIZE (1..67))
      -- 64 characters for name, 1 for "/", 2 for version to match ABNF
   }

   PackagesDescriptor ::= SEQUENCE OF PackagesItem

   PackagesItem ::= SEQUENCE
   {
      packageName       Name,
      packageVersion    INTEGER(0..99),
      ...
   }

   StatisticsDescriptor ::= SEQUENCE OF StatisticsParameter

   StatisticsParameter ::= SEQUENCE
   {
      statName       PkgdName,
      statValue      Value OPTIONAL
   }

   NonStandardData ::= SEQUENCE
   {
      nonStandardIdentifier   NonStandardIdentifier,
      data                    OCTET STRING
   }

   NonStandardIdentifier ::= CHOICE
   {
      object            OBJECT IDENTIFIER,
      h221NonStandard   H221NonStandard,
      experimental      IA5String(SIZE(8)),
          -- first two characters should be "X-" or "X+"
      ...
   }

   H221NonStandard ::= SEQUENCE
   {  t35CountryCode1   INTEGER(0..255),
      t35CountryCode2   INTEGER(0..255),      -- country, as per T.35
      t35Extension      INTEGER(0..255),      -- assigned nationally
      manufacturerCode     INTEGER(0..65535), -- assigned nationally
      ...
   }

   TimeNotation ::= SEQUENCE
   {
      date     IA5String(SIZE(8)),  -- yyyymmdd format
      time     IA5String(SIZE(8))   -- hhmmssss format
      -- per ISO 8601:1988
   }

   Value ::= SEQUENCE OF OCTET STRING

   END

A.3   Digit maps and path names

   From a syntactic viewpoint, digit maps are strings with syntactic
   restrictions imposed upon them.  The syntax of valid digit maps is
   specified in ABNF [RFC 2234].  The syntax for digit maps presented in
   this subclause is for illustrative purposes only.  The definition of
   digitMap in Annex B takes precedence in the case of differences
   between the two.

     digitMap = (digitString / LWSP "(" LWSP digitStringList LWSP ")"
               LWSP)

     digitStringList = digitString *( LWSP "|" LWSP digitString )
     digitString = 1*(digitStringElement)
     digitStringElement = digitPosition [DOT]
     digitPosition = digitMapLetter / digitMapRange
     digitMapRange = ("x" / (LWSP "[" LWSP digitLetter LWSP "]" LWSP))
     digitLetter = *((DIGIT "-" DIGIT) /digitMapLetter)
     digitMapLetter = DIGIT           ;digits 0-9
             / %x41-4B / %x61-6B    ;a-k and A-K
             / "L"/ "S"       ;Inter-event timers
                                 ;(long, short)
             / "Z"            ;Long duration event
     DOT = %x2E ; "."
     LWSP = *(WSP / COMMENT / EOL)
     WSP = SP / HTAB
     COMMENT = ";" *(SafeChar / RestChar / WSP) EOL
     EOL = (CR [LF]) / LF
     SP = %x20
     HTAB = %x09
     CR = %x0D
     LF = %x0A
     SafeChar = DIGIT / ALPHA / "+" / "-" / "&" / "!" / "_" / "/" /
         "'" / "?" / "@" / "^" / "`" / "~" / "*" / "$" / "\" /
         "(" / ")" / "%" / "."
     RestChar = ";" / "[" / "]" / "{" / "}" / ":" / "," / "#" /
         "<" / ">" / "=" / %x22
     DIGIT = %x30-39       ; digits 0 through 9
     ALPHA = %x41-5A / %x61-7A; A-Z, a-z

   A path name is also a string with syntactic restrictions imposed upon
   it.  The ABNF production defining it is copied from Annex B.

     ; Total length of pathNAME must not exceed 64 chars.
     pathNAME = ["*"] NAME *("/" / "*"/ ALPHA / DIGIT /"_" / "$" )
                            ["@" pathDomainName ]

     ; ABNF allows two or more consecutive "." although it is
     ; meaningless in a path domain name.
     pathDomainName       = (ALPHA / DIGIT / "*" )
                            *63(ALPHA / DIGIT / "-"
     NAME = ALPHA *63(ALPHA / DIGIT / "_" )

ANNEX B - Text encoding of the protocol

B.1   Coding of wildcards

   In a text encoding of the protocol, while TerminationIDs are
   arbitrary, by judicious choice of names, the wildcard character, "*"
   may be made more useful.  When the wildcard character is encountered,
   it will "match" all TerminationIDs having the same previous and
   following characters (if appropriate).  For example, if there were
   TerminationIDs of R13/3/1, R13/3/2 and R13/3/3, the TerminationID
   R13/3/* would match all of them.  There are some circumstances where
   ALL Terminations must be referred to.  The TerminationID "*"
   suffices, and is referred to as ALL.  The CHOOSE TerminationID "$"
   may be used to signal to the MG that it has to create an ephemeral
   Termination or select an idle physical Termination.

B.2   ABNF specification

   The protocol syntax is presented in ABNF according to RFC 2234.

      Note 1 - This syntax specification does not enforce all
      restrictions on element inclusions and values.  Some additional
      restrictions are stated in comments and other restrictions appear
      in the text of this RFC.  These additional restrictions are part
      of the protocol even though not enforced by this specification.

      Note 2 - The syntax is context-dependent.  For example, "Add" can
      be the AddToken or a NAME depending on the context in which it
      occurs.

   Everything in the ABNF and text encoding is case insensitive.  This
   includes TerminationIDs, digitmap Ids etc.  SDP is case sensitive as
   per RFC 2327.

   ; NOTE -- The ABNF in this section uses the VALUE construct (or lists
   ; of VALUE constructs) to encode various package element values
   ; (properties, signal parameters, etc.).  The types of these values
   ; vary and are specified the relevant package definition.  Several
   ; such types are described in section 12.2.
   ;
   ; The ABNF specification for VALUE allows a quotedString form or a
   ; collection of SafeChars.  The encoding of package element values
   ; into ABNF VALUES is specified below.  If a type's encoding allows
   ; characters other than SafeChars, the quotedString form MUST be used
   ; for all values of that type, even for specific values that consist
   ; only of SafeChars.
   ;

   ; String:  A string MUST use the quotedString form of VALUE and can
   ; contain anything allowable in the quotedString form.
   ;
   ; Integer, Double, and Unsigned Integer:  Decimal values can be
   ; encoded using characters 0-9.  Hexadecimal values must be prefixed
   ; with '0x' and can use characters 0-9,a-f,A-F.  An octal format is
   ; not supported.  Negative integers start with '-' and MUST be
   ; Decimal.  The SafeChar form of VALUE MUST be used.
   ;
   ; Character:  A UTF-8 encoding of a single letter surrounded by
   ; double quotes.
   ;
   ; Enumeration:  An enumeration MUST use the SafeChar form of VALUE
   ; and can contain anything allowable in the SafeChar form.
   ;
   ; Boolean:  Boolean values are encoded as "on" and "off" and are
   ; case insensitive.  The SafeChar form of VALUE MUST be used.
   ;
   ; Future types:  Any defined types MUST fit within
   ; the ABNF specification of VALUE.  Specifically, if a type's
   ; encoding allows characters other than SafeChars, the quotedString
   ; form MUST be used for all values of that type, even for specific
   ; values that consist only of SafeChars.
   ;
   ; Note that there is no way to use the double quote character within
   ; a value.
   ;
   ; Note that SDP disallows whitespace at the beginning of a line,
   ; Megaco ABNF allows whitespace before the beginning of the SDP in
   ; the Local/Remote descriptor.  Parsers should accept whitespace
   ; between the LBRKT following the Local/Remote token and the
   ; beginning of the SDP.

   megacoMessage        = LWSP [authenticationHeader SEP ] message

   authenticationHeader = AuthToken EQUAL SecurityParmIndex COLON
                          SequenceNum COLON AuthData

   SecurityParmIndex    = "0x" 8(HEXDIG)
   SequenceNum          = "0x" 8(HEXDIG)
   AuthData             = "0x" 24*64(HEXDIG)

   message            = MegacopToken SLASH Version SEP mId SEP
   messageBody
   ; The version of the protocol defined here is equal to 1.

   messageBody          = ( errorDescriptor / transactionList )

   transactionList      = 1*( transactionRequest / transactionReply /
                          transactionPending / transactionResponseAck )
   ;Use of response acks is dependent on underlying transport


   transactionPending   = PendingToken EQUAL TransactionID LBRKT
   RBRKT

   transactionResponseAck = ResponseAckToken LBRKT transactionAck
                  *(COMMA transactionAck) RBRKT
   transactionAck = transactionID / (transactionID "-" transactionID)

   transactionRequest   = TransToken EQUAL TransactionID LBRKT
                          actionRequest *(COMMA actionRequest) RBRKT

   actionRequest        = CtxToken EQUAL ContextID LBRKT ((
                          contextRequest [COMMA  commandRequestList])
                          / commandRequestList) RBRKT

   contextRequest    = ((contextProperties [COMMA contextAudit])
               / contextAudit)

   contextProperties    = contextProperty *(COMMA contextProperty)

   ; at-most-once
   contextProperty    = (topologyDescriptor / priority / EmergencyToken)

   contextAudit   = ContextAuditToken LBRKT contextAuditProperties
                         *(COMMA contextAuditProperties) RBRKT

   ; at-most-once
   contextAuditProperties = ( TopologyToken / EmergencyToken /
                              PriorityToken )

   ; "O-" indicates an optional command
   ; "W-" indicates a wildcarded response to a command
   commandRequestList = ["O-"] ["W-"] commandRequest
                        *(COMMA ["O-"] ["W-"]commandRequest)

   commandRequest      = ( ammRequest / subtractRequest / auditRequest /
                           notifyRequest / serviceChangeRequest)

   transactionReply     = ReplyToken EQUAL TransactionID LBRKT
                     [ ImmAckRequiredToken COMMA]
                   ( errorDescriptor / actionReplyList ) RBRKT

   actionReplyList      = actionReply *(COMMA actionReply )

   actionReply          = CtxToken EQUAL ContextID LBRKT
                     ( errorDescriptor / commandReply ) /
            (commandReply COMMA errorDescriptor) ) RBRKT

   commandReply      = (( contextProperties [COMMA commandReplyList] ) /
                           commandReplyList )


   commandReplyList     = commandReplys *(COMMA commandReplys )

   commandReplys        = (serviceChangeReply / auditReply / ammsReply /
                           notifyReply )

   ;Add Move and Modify have the same request parameters
   ammRequest           = (AddToken / MoveToken / ModifyToken ) EQUAL
                          TerminationID [LBRKT ammParameter *(COMMA
                          ammParameter) RBRKT]

   ;at-most-once
   ammParameter         = (mediaDescriptor / modemDescriptor /
                           muxDescriptor / eventsDescriptor /
                           signalsDescriptor / digitMapDescriptor /
                           eventBufferDescriptor / auditDescriptor)

   ammsReply            = (AddToken / MoveToken / ModifyToken /
                           SubtractToken ) EQUAL TerminationID [ LBRKT
                           terminationAudit RBRKT ]

   subtractRequest      =  SubtractToken EQUAL TerminationID
                           [ LBRKT auditDescriptor RBRKT]

   auditRequest         =  (AuditValueToken / AuditCapToken ) EQUAL
                           TerminationID LBRKT auditDescriptor RBRKT

   auditReply           = (AuditValueToken / AuditCapToken )
                          ( contextTerminationAudit  / auditOther)

   auditOther           = EQUAL TerminationID [LBRKT
                          terminationAudit RBRKT]

   terminationAudit = auditReturnParameter *(COMMA auditReturnParameter)

   contextTerminationAudit = EQUAL CtxToken ( terminationIDList /
                          LBRKT errorDescriptor RBRKT )

   auditReturnParameter = (mediaDescriptor / modemDescriptor /
                           muxDescriptor / eventsDescriptor /
                           signalsDescriptor / digitMapDescriptor /

                      observedEventsDescriptor / eventBufferDescriptor /
                           statisticsDescriptor / packagesDescriptor /
                            errorDescriptor / auditItem)

   auditDescriptor      = AuditToken LBRKT [ auditItem
                          *(COMMA auditItem) ] RBRKT

   notifyRequest        = NotifyToken EQUAL TerminationID
                          LBRKT ( observedEventsDescriptor
                                [ COMMA errorDescriptor ] ) RBRKT

   notifyReply          = NotifyToken EQUAL TerminationID
                          [ LBRKT errorDescriptor RBRKT ]

   serviceChangeRequest = ServiceChangeToken EQUAL TerminationID
                          LBRKT serviceChangeDescriptor RBRKT

   serviceChangeReply   = ServiceChangeToken EQUAL TerminationID
                          [LBRKT (errorDescriptor /
                          serviceChangeReplyDescriptor) RBRKT]

   errorDescriptor   = ErrorToken EQUAL ErrorCode
                       LBRKT [quotedString] RBRKT

   ErrorCode            = 1*4(DIGIT) ; could be extended

   TransactionID        = UINT32

   mId                  = (( domainAddress / domainName )
                          [":" portNumber]) / mtpAddress / deviceName

   ; ABNF allows two or more consecutive "." although it is meaningless
   ; in a domain name.
   domainName           = "<" (ALPHA / DIGIT) *63(ALPHA / DIGIT / "-" /
                          ".") ">"
   deviceName           = pathNAME

   ;The values 0x0, 0xFFFFFFFE and 0xFFFFFFFF are reserved.
   ContextID            = (UINT32 / "*" / "-" / "$")

   domainAddress        = "[" (IPv4address / IPv6address) "]"
   ;RFC2373 contains the definition of IP6Addresses.
   IPv6address          = hexpart [ ":" IPv4address ]
   IPv4address          = V4hex DOT V4hex DOT V4hex DOT V4hex
   V4hex                = 1*3(DIGIT) ; "0".."255"
   ; this production, while occurring in RFC2373, is not referenced
   ; IPv6prefix           = hexpart SLASH 1*2DIGIT
   hexpart           = hexseq "::" [ hexseq ] / "::" [ hexseq ] / hexseq

   hexseq               = hex4 *( ":" hex4)
   hex4                 = 1*4HEXDIG

   portNumber           = UINT16

   ; Addressing structure of mtpAddress:
   ; 25 - 15            0
   ;    |  PC        | NI |
   ;    24 - 14 bits    2 bits
   ; Note: 14 bits are defined for international use.
   ; Two national options exist where the point code is 16 or 24 bits.
   ; To octet align the mtpAddress the MSBs shall be encoded as 0s.
   ; An octet shall be represented by 2 hex digits.
   mtpAddress           = MTPToken LBRKT 4*8 (HEXDIG) RBRKT

   terminationIDList  = LBRKT TerminationID *(COMMA TerminationID) RBRKT

   ; Total length of pathNAME must not exceed 64 chars.
   pathNAME      = ["*"] NAME *("/" / "*"/ ALPHA / DIGIT /"_" / "$" )
                          ["@" pathDomainName ]

   ; ABNF allows two or more consecutive "." although it is meaningless
   ; in a path domain name.
   pathDomainName       = (ALPHA / DIGIT / "*" )
                          *63(ALPHA / DIGIT / "-" / "*" / ".")

   TerminationID        = "ROOT" / pathNAME / "$" / "*"

   mediaDescriptor = MediaToken LBRKT mediaParm *(COMMA mediaParm) RBRKT

   ; at-most one terminationStateDescriptor
   ; and either streamParm(s) or streamDescriptor(s) but not both
   mediaParm            = (streamParm / streamDescriptor /
                           terminationStateDescriptor)

   ; at-most-once per item
   streamParm           = ( localDescriptor / remoteDescriptor /
                           localControlDescriptor )

   streamDescriptor     = StreamToken EQUAL StreamID LBRKT streamParm
                          *(COMMA streamParm) RBRKT

   localControlDescriptor = LocalControlToken LBRKT localParm
                            *(COMMA localParm) RBRKT

   ; at-most-once per item except for propertyParm
   localParm = ( streamMode / propertyParm / reservedValueMode
                  / reservedGroupMode )

   reservedValueMode    = ReservedValueToken EQUAL ( "ON" / "OFF" )
   reservedGroupMode    = ReservedGroupToken EQUAL ( "ON" / "OFF" )

   streamMode           = ModeToken EQUAL streamModes

   streamModes     = (SendonlyToken / RecvonlyToken / SendrecvToken /
                          InactiveToken / LoopbackToken )

   propertyParm         = pkgdName parmValue
   parmValue            = (EQUAL alternativeValue/ INEQUAL VALUE)
   alternativeValue     = ( VALUE
                  / LSBRKT VALUE *(COMMA VALUE) RSBRKT
                   ; sublist (i.e., A AND B AND ...)
                  / LBRKT VALUE *(COMMA VALUE) RBRKT
                   ; alternatives (i.e., A OR B OR ...)
                  /  LSBRKT VALUE COLON VALUE RSBRKT )
                   ; range

   INEQUAL              = LWSP (">" / "<" / "#" ) LWSP
   LSBRKT               = LWSP "[" LWSP
   RSBRKT               = LWSP "]" LWSP

   ; Note - The octet zero is not among the permitted characters in
   ; octet string.  As the current definition is limited to SDP, and a
   ; zero octet would not be a legal character in SDP, this is not a
   ; concern.

   localDescriptor      = LocalToken LBRKT octetString RBRKT

   remoteDescriptor     = RemoteToken LBRKT octetString RBRKT

   eventBufferDescriptor= EventBufferToken [ LBRKT eventSpec
                          *( COMMA eventSpec) RBRKT ]

   eventSpec      = pkgdName [ LBRKT eventSpecParameter
                *(COMMA eventSpecParameter) RBRKT ]
   eventSpecParameter   = (eventStream / eventOther)

   eventBufferControl     = BufferToken EQUAL ( "OFF" / LockStepToken )

   terminationStateDescriptor = TerminationStateToken LBRKT
              terminationStateParm *( COMMA terminationStateParm ) RBRKT

   ; at-most-once per item except for propertyParm
   terminationStateParm = (propertyParm / serviceStates /
                           eventBufferControl )

   serviceStates        = ServiceStatesToken EQUAL ( TestToken /
                          OutOfSvcToken / InSvcToken )

   muxDescriptor        = MuxToken EQUAL MuxType  terminationIDList

   MuxType              = ( H221Token / H223Token / H226Token / V76Token
                           / extensionParameter )

   StreamID             = UINT16
   pkgdName     = (PackageName SLASH ItemID) ;specific item
                / (PackageName SLASH "*") ;all items in package
                / ("*" SLASH "*") ; all items supported by the MG
   PackageName          = NAME
   ItemID               = NAME

   eventsDescriptor     = EventsToken [ EQUAL RequestID LBRKT
                        requestedEvent *( COMMA requestedEvent ) RBRKT ]

   requestedEvent       = pkgdName [ LBRKT eventParameter
                          *( COMMA eventParameter ) RBRKT ]

   ; at-most-once each of KeepActiveToken , eventDM and eventStream
   ;at most one of either embedWithSig or embedNoSig but not both
   ;KeepActiveToken and embedWithSig must not both be present
   eventParameter       = ( embedWithSig / embedNoSig / KeepActiveToken
                            /eventDM / eventStream / eventOther )

   embedWithSig         = EmbedToken LBRKT signalsDescriptor
                            [COMMA embedFirst ] RBRKT
   embedNoSig        = EmbedToken LBRKT embedFirst RBRKT

   ; at-most-once of each
   embedFirst      = EventsToken [ EQUAL RequestID LBRKT
              secondRequestedEvent *(COMMA secondRequestedEvent) RBRKT ]

   secondRequestedEvent = pkgdName [ LBRKT secondEventParameter
                          *( COMMA secondEventParameter ) RBRKT ]

   ; at-most-once each of embedSig , KeepActiveToken, eventDM or
   ; eventStream
   ; KeepActiveToken and embedSig must not both be present
   secondEventParameter = ( embedSig / KeepActiveToken / eventDM /
                            eventStream / eventOther )

   embedSig  = EmbedToken LBRKT signalsDescriptor RBRKT

   eventStream          = StreamToken EQUAL StreamID

   eventOther           = eventParameterName parmValue

   eventParameterName   = NAME

   eventDM              = DigitMapToken EQUAL(( digitMapName ) /
                          (LBRKT digitMapValue RBRKT ))

   signalsDescriptor    = SignalsToken LBRKT [ signalParm
                          *(COMMA signalParm)] RBRKT

   signalParm           = signalList / signalRequest

   signalRequest        = signalName [ LBRKT sigParameter
                          *(COMMA sigParameter) RBRKT ]

   signalList           = SignalListToken EQUAL signalListId LBRKT
                          signalListParm *(COMMA signalListParm) RBRKT

   signalListId         = UINT16

   ;exactly once signalType, at most once duration and every signal
   ;parameter
   signalListParm       = signalRequest

   signalName           = pkgdName
   ;at-most-once sigStream, at-most-once sigSignalType,
   ;at-most-once sigDuration, every signalParameterName at most once
   sigParameter = sigStream / sigSignalType / sigDuration / sigOther
               / notifyCompletion / KeepActiveToken
   sigStream            = StreamToken EQUAL StreamID
   sigOther             = sigParameterName parmValue
   sigParameterName     = NAME
   sigSignalType        = SignalTypeToken EQUAL signalType
   signalType           = (OnOffToken / TimeOutToken / BriefToken)
   sigDuration          = DurationToken EQUAL UINT16
   notifyCompletion     = NotifyCompletionToken EQUAL (LBRKT
            notificationReason *(COMMA notificationReason) RBRKT)

   notificationReason   = ( TimeOutToken / InterruptByEventToken
                        / InterruptByNewSignalsDescrToken
                        / OtherReasonToken )
   observedEventsDescriptor = ObservedEventsToken EQUAL RequestID
                      LBRKT observedEvent *(COMMA observedEvent) RBRKT

   ;time per event, because it might be buffered
   observedEvent        = [ TimeStamp LWSP COLON] LWSP
                          pkgdName [ LBRKT observedEventParameter
                          *(COMMA observedEventParameter) RBRKT ]

   ;at-most-once eventStream, every eventParameterName at most once
   observedEventParameter = eventStream / eventOther

   ; For an AuditCapReply with all events, the RequestID should be ALL.
   RequestID            = ( UINT32 / "*" )

   modemDescriptor      = ModemToken (( EQUAL modemType) /
                      (LSBRKT modemType *(COMMA modemType) RSBRKT))
                     [ LBRKT propertyParm *(COMMA propertyParm) RBRKT ]


   ; at-most-once except for extensionParameter
   modemType            = (V32bisToken / V22bisToken / V18Token /
                           V22Token / V32Token / V34Token / V90Token /
                         V91Token / SynchISDNToken / extensionParameter)

   digitMapDescriptor  = DigitMapToken EQUAL
                        ( ( LBRKT digitMapValue RBRKT ) /
                        (digitMapName [ LBRKT digitMapValue RBRKT ]) )
   digitMapName        = NAME
   digitMapValue       = ["T" COLON Timer COMMA] ["S" COLON Timer COMMA]
                         ["L" COLON Timer COMMA] digitMap
   Timer               = 1*2DIGIT
   ; Units are seconds for T, S, and L timers, and hundreds of
   ; milliseconds for Z timer.  Thus T, S, and L range from 1 to 99
   ; seconds and Z from 100 ms to 9.9 s
   digitMap = (digitString /
               LWSP "(" LWSP digitStringList LWSP ")" LWSP)
   digitStringList   = digitString *( LWSP "|" LWSP digitString )
   digitString       = 1*(digitStringElement)
   digitStringElement = digitPosition [DOT]
   digitPosition     = digitMapLetter / digitMapRange
   digitMapRange     = ("x" / (LWSP "[" LWSP digitLetter LWSP "]" LWSP))
   digitLetter       = *((DIGIT "-" DIGIT ) / digitMapLetter)
   digitMapLetter    = DIGIT   ;Basic event symbols
               / %x41-4B / %x61-6B ; a-k, A-K
               / "L" / "S"   ;Inter-event timers (long, short)
               / "Z"         ;Long duration modifier

   ;at-most-once, and DigitMapToken and PackagesToken are not allowed
   ;in AuditCapabilities command
   auditItem            = ( MuxToken / ModemToken / MediaToken /
                           SignalsToken / EventBufferToken /
                           DigitMapToken / StatsToken / EventsToken /
                           ObservedEventsToken / PackagesToken )

   serviceChangeDescriptor = ServicesToken LBRKT serviceChangeParm
                            *(COMMA serviceChangeParm) RBRKT

   ; each parameter at-most-once
   ; at most one of either serviceChangeAddress or serviceChangeMgcId
   ; but not both
   ; serviceChangeMethod and serviceChangeReason are REQUIRED
   serviceChangeParm    = (serviceChangeMethod / serviceChangeReason /
                          serviceChangeDelay / serviceChangeAddress /
                          serviceChangeProfile / extension / TimeStamp /
                          serviceChangeMgcId / serviceChangeVersion )

   serviceChangeReplyDescriptor = ServicesToken LBRKT
                        servChgReplyParm *(COMMA servChgReplyParm) RBRKT

   ; at-most-once.  Version is REQUIRED on first ServiceChange response
   ; at most one of either serviceChangeAddress or serviceChangeMgcId
   ; but not both
   servChgReplyParm     = (serviceChangeAddress / serviceChangeMgcId /
                          serviceChangeProfile / serviceChangeVersion /
                          TimeStamp)
   serviceChangeMethod  = MethodToken EQUAL (FailoverToken /
                          ForcedToken / GracefulToken / RestartToken /
                          DisconnectedToken / HandOffToken /
                          extensionParameter)
   ; A serviceChangeReason consists of a numeric reason code
   ; and an optional text description.
   ; A serviceChangeReason MUST be encoded using the quotedString
   ; form of VALUE.
   ; The quotedString SHALL contain a decimal reason code,
   ; optionally followed by a single space character and a
   ; textual description string.


   serviceChangeReason  = ReasonToken  EQUAL VALUE
   serviceChangeDelay   = DelayToken   EQUAL UINT32
   serviceChangeAddress = ServiceChangeAddressToken EQUAL ( mId /
                          portNumber )
   serviceChangeMgcId   = MgcIdToken   EQUAL mId
   serviceChangeProfile = ProfileToken EQUAL NAME SLASH Version
   serviceChangeVersion = VersionToken EQUAL Version
   extension            = extensionParameter parmValue

   packagesDescriptor   = PackagesToken LBRKT packagesItem
                          *(COMMA packagesItem) RBRKT

   Version              = 1*2(DIGIT)
   packagesItem         = NAME "-" UINT16

   TimeStamp            = Date "T" Time ; per ISO 8601:1988
   ; Date = yyyymmdd
   Date                 = 8(DIGIT)
   ; Time = hhmmssss
   Time                 = 8(DIGIT)
   statisticsDescriptor = StatsToken LBRKT statisticsParameter
                         *(COMMA statisticsParameter ) RBRKT

   ;at-most-once per item
   statisticsParameter  = pkgdName [EQUAL VALUE]

   topologyDescriptor   = TopologyToken LBRKT topologyTriple
                          *(COMMA topologyTriple) RBRKT
   topologyTriple       = terminationA COMMA
                          terminationB COMMA topologyDirection
   terminationA         = TerminationID
   terminationB         = TerminationID
   topologyDirection    = BothwayToken / IsolateToken / OnewayToken

   priority             = PriorityToken EQUAL UINT16

   extensionParameter   = "X"  ("-" / "+") 1*6(ALPHA / DIGIT)

   ; octetString is used to describe SDP defined in RFC2327.
   ; Caution should be taken if CRLF in RFC2327 is used.
   ; To be safe, use EOL in this ABNF.
   ; Whenever "}" appears in SDP, it is escaped by "\", e.g., "\}"
   octetString          = *(nonEscapeChar)
   nonEscapeChar        = ( "\}" / %x01-7C / %x7E-FF )
   ; Note - The double-quote character is not allowed in quotedString.
   quotedString         = DQUOTE *(SafeChar / RestChar/ WSP) DQUOTE

   UINT16               = 1*5(DIGIT)  ; %x0-FFFF
   UINT32               = 1*10(DIGIT) ; %x0-FFFFFFFF

   NAME                 = ALPHA *63(ALPHA / DIGIT / "_" )
   VALUE                = quotedString / 1*(SafeChar)
   SafeChar             = DIGIT / ALPHA / "+" / "-" / "&" /
                          "!" / "_" / "/" / "\'" / "?" / "@" /
                          "^" / "`" / "~" / "*" / "$" / "\" /
                          "(" / ")" / "%" / "|" / "."

   EQUAL                = LWSP %x3D LWSP ; "="
   COLON                = %x3A           ; ":"
   LBRKT                = LWSP %x7B LWSP ; "{"
   RBRKT                = LWSP %x7D LWSP ; "}"
   COMMA                = LWSP %x2C LWSP ; ","

   DOT                  = %x2E           ; "."
   SLASH                = %x2F           ; "/"
   ALPHA                = %x41-5A / %x61-7A ; A-Z / a-z
   DIGIT                = %x30-39         ; 0-9
   DQUOTE               = %x22            ; " (Double Quote)
   HEXDIG               = ( DIGIT / "A" / "B" / "C" / "D" / "E" / "F" )
   SP                   = %x20        ; space
   HTAB                 = %x09        ; horizontal tab
   CR                   = %x0D        ; Carriage return
   LF                   = %x0A        ; linefeed
   LWSP                 = *( WSP / COMMENT / EOL )
   EOL                  = (CR [LF] / LF )
   WSP                  = SP / HTAB ; white space
   SEP                  = ( WSP / EOL / COMMENT) LWSP
   COMMENT              = ";" *(SafeChar/ RestChar / WSP / %x22) EOL
   RestChar            = ";" / "[" / "]" / "{" / "}" / ":" / "," / "#" /
                          "<" / ">" / "="

   ; New Tokens added to sigParameter must take the format of SPA*
   ; * may be of any form i.e., SPAM
   ; New Tokens added to eventParameter must take the form of EPA*
   ; * may be of any form i.e., EPAD

   AddToken                   = ("Add"                   / "A")
   AuditToken                 = ("Audit"                 / "AT")
   AuditCapToken              = ("AuditCapability"       / "AC")
   AuditValueToken            = ("AuditValue"            / "AV")
   AuthToken                  = ("Authentication"        / "AU")
   BothwayToken               = ("Bothway"               / "BW")
   BriefToken                 = ("Brief"                 / "BR")
   BufferToken                = ("Buffer"                / "BF")
   CtxToken                   = ("Context"               / "C")
   ContextAuditToken       = ("ContextAudit"    / "CA")
   DigitMapToken              = ("DigitMap"              / "DM")
   DisconnectedToken          = ("Disconnected"          / "DC")
   DelayToken                 = ("Delay"                 / "DL")
   DurationToken              = ("Duration"              / "DR")
   EmbedToken                 = ("Embed"                 / "EM")
   EmergencyToken             = ("Emergency"             / "EG")
   ErrorToken                 = ("Error"                 / "ER")
   EventBufferToken           = ("EventBuffer"           / "EB")
   EventsToken                = ("Events"                / "E")
   FailoverToken              = ("Failover"              / "FL")
   ForcedToken                = ("Forced"                / "FO")
   GracefulToken              = ("Graceful"              / "GR")
   H221Token                  = ("H221" )
   H223Token                  = ("H223" )
   H226Token                  = ("H226" )

   HandOffToken               = ("HandOff"               / "HO")
   ImmAckRequiredToken        = ("ImmAckRequired"        / "IA")
   InactiveToken              = ("Inactive"              / "IN")
   IsolateToken               = ("Isolate"               / "IS")
   InSvcToken                 = ("InService"             / "IV")
   InterruptByEventToken      = ("IntByEvent"            / "IBE")
   InterruptByNewSignalsDescrToken
                              = ("IntBySigDescr"         / "IBS")
   KeepActiveToken            = ("KeepActive"            / "KA")
   LocalToken                 = ("Local"                 / "L")
   LocalControlToken          = ("LocalControl"          / "O")
   LockStepToken              = ("LockStep"              / "SP")
   LoopbackToken              = ("Loopback"              / "LB")
   MediaToken                 = ("Media"                 / "M")
   MegacopToken               = ("MEGACO"                / "!")
   MethodToken                = ("Method"                / "MT")
   MgcIdToken                 = ("MgcIdToTry"            / "MG")
   ModeToken                  = ("Mode"                  / "MO")
   ModifyToken                = ("Modify"                / "MF")
   ModemToken                 = ("Modem"                 / "MD")
   MoveToken                  = ("Move"                  / "MV")
   MTPToken                   = ("MTP")
   MuxToken                   = ("Mux"                   / "MX")
   NotifyToken                = ("Notify"                / "N")
   NotifyCompletionToken      = ("NotifyCompletion"      / "NC")
   ObservedEventsToken        = ("ObservedEvents"        / "OE")
   OnewayToken                = ("Oneway"                / "OW")
   OnOffToken                 = ("OnOff"                 / "OO")
   OtherReasonToken           = ("OtherReason"           / "OR")
   OutOfSvcToken              = ("OutOfService"          / "OS")
   PackagesToken              = ("Packages"              / "PG")
   PendingToken               = ("Pending"               / "PN")
   PriorityToken              = ("Priority"              / "PR")
   ProfileToken               = ("Profile"               / "PF")
   ReasonToken                = ("Reason"                / "RE")
   RecvonlyToken              = ("ReceiveOnly"           / "RC")
   ReplyToken                 = ("Reply"                 / "P")
   RestartToken               = ("Restart"               / "RS")
   RemoteToken                = ("Remote"                / "R")
   ReservedGroupToken         = ("ReservedGroup"         / "RG")
   ReservedValueToken         = ("ReservedValue"         / "RV")
   SendonlyToken              = ("SendOnly"              / "SO")
   SendrecvToken              = ("SendReceive"           / "SR")
   ServicesToken              = ("Services"              / "SV")
   ServiceStatesToken         = ("ServiceStates"         / "SI")
   ServiceChangeToken         = ("ServiceChange"         / "SC")
   ServiceChangeAddressToken  = ("ServiceChangeAddress"  / "AD")
   SignalListToken            = ("SignalList"            / "SL")

   SignalsToken               = ("Signals"               / "SG")
   SignalTypeToken            = ("SignalType"            / "SY")
   StatsToken                 = ("Statistics"            / "SA")
   StreamToken                = ("Stream"                / "ST")
   SubtractToken              = ("Subtract"              / "S")
   SynchISDNToken             = ("SynchISDN"             / "SN")
   TerminationStateToken      = ("TerminationState"      / "TS")
   TestToken                  = ("Test"                  / "TE")
   TimeOutToken               = ("TimeOut"               / "TO")
   TopologyToken              = ("Topology"              / "TP")
   TransToken                 = ("Transaction"           / "T")
   ResponseAckToken           = ("TransactionResponseAck" / "K")
   V18Token                   = ("V18")
   V22Token                   = ("V22")
   V22bisToken                = ("V22b")
   V32Token                   = ("V32")
   V32bisToken                = ("V32b")
   V34Token                   = ("V34")
   V76Token                   = ("V76")
   V90Token                   = ("V90")
   V91Token                   = ("V91")
   VersionToken               = ("Version"               / "V")

B.3   Hexadecimal octet coding

   Hexadecimal octet coding is a means for representing a string of
   octets as a string of hexadecimal digits, with two digits
   representing each octet.  This octet encoding should be used when
   encoding octet strings in the text version of the protocol.  For each
   octet, the 8-bit sequence is encoded as two hexadecimal digits.  Bit
   0 is the first transmitted; bit 7 is the last.  Bits 7-4 are encoded
   as the first hexadecimal digit, with Bit 7 as MSB and Bit 4 as LSB.
   Bits 3-0 are encoded as the second hexadecimal digit, with Bit 3 as
   MSB and Bit 0 as LSB. Examples:

        Octet bit pattern                   Hexadecimal coding
        00011011                            D8
        11100100                            27
        10000011 10100010 11001000 00001001 C1451390

B.4   Hexadecimal octet sequence

   A hexadecimal octet sequence is an even number of hexadecimal digits,
   terminated by a <CR> character.

ANNEX C - Tags for media stream properties

   Parameters for Local, Remote and LocalControl descriptors are
   specified as tag-value pairs if binary encoding is used for the
   protocol.  This annex contains the property names (PropertyID), the
   tags (Property tag), type of the property (Type) and the values
   (Value).  Values presented in the Value field when the field contains
   references shall be regarded as "information".  The reference
   contains the normative values.  If a value field does not contain a
   reference, then the values in that field can be considered as
   "normative".

   Tags are given as hexadecimal numbers in this annex.  When setting
   the value of a property, a MGC may underspecify the value according
   to one of the mechanisms specified in 7.1.1.

   It is optional to support the properties in this Annex or any of its
   sub-sections.  For example, only three properties from C.3 and only
   five properties from C.8 might be implemented.

   For type "enumeration" the value is represented by the value in
   brackets, e.g., Send(0), Receive(1).  Annex C properties with the
   types "N bits" or "M Octets" should be treated as octet strings when
   encoding the protocol.  Properties with "N bit integer" shall be
   treated as an integers.  "String" shall be treated as an IA5String
   when encoding the protocol.

   When a type is smaller than one octet, the value shall be stored in
   the low-order bits of an octet string of size 1.

C.1   General media attributes

   PropertyID    Property Type          Value
                 tag

   Media         1001     Enumeration   Audio(0), Video(1), Data(2)

   Transmission  1002     Enumeration   Send(0), Receive(1),
   mode                                 Send&Receive(2)

   Number of     1003     Unsigned      0-255
   Channels               integer

   Sampling      1004     Unsigned      0-2^32
   rate                   integer

   Bitrate       1005     Integer       (0..4294967295)NOTE - Units of
                                        100 bit/s.

   ACodec        1006     Octet string  Audio Codec Type:
                                        Ref.: ITU-T Q.765
                                        Non-ITU-T codecs are defined
                                        with the appropriate standards
                                        organization under a defined
                                        Organizational Identifier.

   Samplepp      1007     Unsigned      Maximum samples or frames per
                          integer       packet: 0..65535

   Silencesupp   1008     Boolean       Silence Suppression: True/False

   Encrypttype   1009     Octet string  Ref.: ITU-T H.245

   Encryptkey    100A     Octet string  Encryption key
                          size          Ref.: ITU-T H.235
                          (0..65535)

   Echocanc      100B                    Not Used.  See H.248.1 E.13 for
                                        an example of possible Echo
                                        Control properties.

   Gain          100C     Unsigned      Gain in dB: 0..65535
                          integer

   Jitterbuff    100D     Unsigned      Jitter buffer size in ms:
                          integer       0..65535

   PropDelay     100E     Unsigned      Propagation Delay: 0..65535
                          integer       Maximum propagation delay in
                                        milliseconds for the bearer
                                        connection between two media
                                        gateways.  The maximum delay
                                        will be dependent on the bearer
                                        technology.

   RTPpayload    100F     Integer       Payload type in RTP Profile for
                                        Audio and Video Conferences
                                        with Minimal Control
                                        Ref.: RFC 1890

C.2   Mux properties

   PropertyID Property tag Type         Value

   H222       2001         Octet string H222LogicalChannelParameters
                                         Ref.: ITU-T H.245

   H223       2002         Octet string H223LogicalChannelParameters
                                         Ref.: ITU-T H.245

   V76        2003         Octet string V76LogicalChannelParameters
                                         Ref.: ITU-T H.245

   H2250      2004         Octet string H2250LogicalChannelParameters
                                         Ref.: ITU-T H.245

C.3   General bearer properties

   PropertyID Property   Type        Value
              tag

   Mediatx    3001       Enumeration Media Transport TypeTDM
                                      Circuit(0), ATM(1), FR(2),
                                      Ipv4(3), Ipv6(4), ...

   BIR        3002       4 octets    Value depends on transport
                                      technology

   NSAP       3003       1-20 octets See NSAP.
                                      Ref.: Annex A/X.213

C.4   General ATM properties

   PropertyID Property Type              Value
              tag

   AESA       4001     20 octets         ATM End System Address

   VPVC       4002     4 octets: VPCI    VPCI/VCI
                        in first two
                        least             Ref.: ITU-T Q.2931
                        significant
                        octets, VCI in
                        second two
                        octets

   SC         4003     Enumeration       Service Category: CBR(0),
                                          nrt-VBR1(1), nrt  VBR2(2),
                                          nrt-VBR3(3), rt-VBR1(4),
                                          rt  VBR2(5), rt-VBR3(6),
                                          UBR1(7), UBR2(8), ABR(9).
                                          Ref.: ATM Forum UNI 4.0

   BCOB       4004     5-bit integer     Broadband Bearer Class
                                          Ref.: ITU-T Q.2961.2

   BBTC       4005     7-bit integer     Broadband Transfer Capability
                                          Ref.: ITU-T Q.2961.1

   ATC        4006     Enumeration       I.371 ATM Traffic
                                          CapabilityDBR(0), SBR1(1),
                                          SBR2(2), SBR3(3), ABT/IT(4),
                                          ABT/DT(5), ABR(6)
                                          Ref.: ITU-T I.371

   STC        4007     2 bits            Susceptibility to clipping:
                                          Bits
                                          2 1
                                          ---
                                          0 0     not susceptible to
                                                  clipping
                                          0 1     susceptible to
                                                  clipping
                                          Ref.: ITU-T Q.2931

   UPCC       4008     2 bits            User Plane Connection
                                          configuration:
                                          Bits
                                          2 1
                                          ---
                                          0 0     point-to-point
                                          0 1     point-to-multipoint
                                          Ref.: ITU-T Q.2931

   PCR0       4009     24-bit integer    Peak Cell Rate (For CLP = 0)
                                          Ref.: ITU-T Q.2931

   SCR0       400A     24-bit integer    Sustainable Cell Rate (For
                                          CLP = 0)
                                          Ref.: ITU-T Q.2961.1

   MBS0       400B     24-bit integer    Maximum Burst Size (For CLP =
                                          0)
                                          Ref.: ITU-T Q.2961.1

   PCR1       400C     24-bit integer    Peak Cell Rate (For CLP = 0 +
                                          1)
                                          Ref.: ITU-T Q.2931

   SCR1       400D     24-bit integer    Sustainable Cell Rate (For
                                          CLP = 0 + 1)
                                          Ref.: ITU-T Q.2961.1

   MBS1       400E     24-bit integer    Maximum Burst Size (For CLP =
                                          0 + 1)
                                          Ref.: ITU-T Q.2961.1

   BEI        400F     Boolean           Best Effort Indicator
                                          Value 1 indicates that BEI is
                                          to be included in the ATM
                                          signaling; value 0 indicates
                                          that BEI is not to be
                                          included in the ATM
                                          signaling.
                                          Ref.: ATM Forum UNI 4.0

   TI         4010     Boolean           Tagging Indicator
                                          Value 0 indicates that
                                          tagging is not allowed; value
                                          1 indicates that tagging is
                                          requested.
                                          Ref.: ITU-T Q.2961.1

   FD         4011     Boolean           Frame Discard
                                          Value 0 indicates that no
                                          frame discard is allowed;
                                          value 1 indicates that frame
                                          discard is allowed.
                                          Ref.: ATM Forum UNI 4.0

   A2PCDV     4012     24-bit integer    Acceptable 2-point CDV
                                          Ref.: ITU-T Q.2965.2

   C2PCDV     4013     24-bit integer    Cumulative 2-point CDV
                                          Ref.: ITU-T Q.2965.2

   APPCDV     4014     24-bit integer    Acceptable P-P CDV
                                          Ref.: ATM Forum UNI 4.0

   CPPCDV     4015     24-bit integer    Cumulative P-P CDV
                                          Ref.: ATM Forum UNI 4.0

   ACLR       4016     8-bit integer     Acceptable Cell Loss Ratio
                                          Ref.: ITU-T Q.2965.2, ATM
                                          Forum UNI 4.0

   MEETD      4017     16-bit integer    Maximum End-to-end transit
                                          delay
                                          Ref.: ITU-T Q.2965.2, ATM
                                          Forum UNI 4.0

   CEETD      4018     16-bit integer    Cumulative End-to-end transit
                                          delay
                                          Ref.: ITU-T Q.2965.2, ATM
                                          Forum UNI 4.0

   QosClass   4019     Integer 0-5          QoS Class

                                            QoS Class     Meaning

                                            0             Default QoS
                                                           associated
                                                           with the ATC
                                                           as defined
                                                           in ITU-T
                                                           Q.2961.2

                                            1             Stringent

                                            2             Tolerant

                                            3             Bi-level

                                            4             Unbounded

                                            5             Stringent
                                                           Bi-level
                                          Ref.: ITU-T Q.2965.1

   AALtype    401A     1 octet           AAL Type
                                          Bits
                                          8 7 6 5 4 3 2 1
                                          ---------------
                                          0 0 0 0 0 0 0 0   AAL for
                                                            voice
                                          0 0 0 0 0 0 0 1   AAL type 1
                                          0 0 0 0 0 0 1 0   AAL type 2
                                          0 0 0 0 0 0 1 1   AAL type
                                                            3/4
                                          0 0 0 0 0 1 0 1   AAL type 5

                                          0 0 0 1 0 0 0 0   user-
                                                            defined AAL
                                          Ref.: ITU-T Q.2931

C.5   Frame Relay

   PropertyID         Property    Type          Value
                      tag

   DLCI               5001        Unsigned      Data link connection
                                  integer       id

   CID                5002        Unsigned      sub-channel id
                                  integer

   SID/Noiselevel     5003        Unsigned      silence insertion
                                  integer       descriptor

   Primary Payload    5004        Unsigned      Primary Payload Type
   type                           integer       Covers FAX and codecs

C.6   IP

   PropertyID Property tag Type                Value

   IPv4       6001         32 bits Ipv4Address Ipv4Address
                                                Ref.: IETF RFC 791

   IPv6       6002         128 bits            IPv6 Address
                                                Ref.: IETF RFC 2460

   Port       6003         Unsigned integer    0..65535

   Porttype   6004         Enumerated          TCP(0), UDP(1), SCTP(2)


C.7   ATM AAL2

   PropertyID Property Type                   Value
              tag

   AESA       7001     20 octets              AAL2 service endpoint
                                                address as defined in
                                                the referenced
                                                Recommendation.
                                                ESEANSEA
                                                Ref.: ITU-T Q.2630.1

   BIR        See C.3  4 octets               Served user generated
                                                reference as defined in
                                                the referenced
                                                Recommendation.
                                                SUGR
                                                Ref.: ITU-T Q.2630.1

   ALC        7002     12 octets              AAL2 link
                                                characteristics as
                                                defined in the
                                                referenced
                                                Recommendation.
                                                Maximum/Average CPS-SDU
                                                bit rate;
                                                Maximum/Average CPS-SDU
                                                size
                                                Ref.: ITU-T Q.2630.1

   SSCS       7003     I.366.2: Audio (8      Service specific
                        octets); Multirate (3  convergence sublayer
                        octets), or I.366.1:   information as defined
                        SAR-assured (14        in:
                        octets);SAR-unassured  - ITU-T Q.2630.1,and
                        (7 octets).            used in:
                                                - ITU-T I.366.2:
                                                Audio/Multirate;
                                                - ITU-T I.366.1: SAR-
                                                assured/unassured.
                                                Ref.: ITU-T Q.2630.1,
                                                I.366.1 and I.366.2

   SUT        7004     1..254 octets          Served user transport
                                                parameter as defined in
                                                the referenced
                                                Recommendation.
                                                Ref.: ITU-T Q.2630.1

   TCI        7005     Boolean                Test connection
                                                indicator as defined in
                                                the referenced
                                                Recommendation.
                                                Ref.: ITU-T Q.2630.1

   Timer_CU   7006     32-bit integer         Timer-CU
                                                Milliseconds to hold
                                                partially filled cell
                                                before sending.

   MaxCPSSDU  7007     8-bit integer          Maximum Common Part
                                                Sublayer Service Data
                                                Unit
                                                Ref.: ITU-T Q.2630.1

   CID        7008     8 bits                 subchannel id: 0-255
                                                Ref.: ITU-T I.363.2
C.8   ATM AAL1

   PropertyID Property   Type        Value
              tag

   BIR        See table  4-29 octets GIT (Generic Identifier
              in C.3                 Transport)
                                      Ref.: ITU-T Q.2941.1

   AAL1ST     8001       1 octet     AAL1 Subtype
                                      Bits
                                      8 7 6 5 4 3 2 1
                                      ---------------
                                      0 0 0 0 0 0 0 0     null
                                      0 0 0 0 0 0 0 1     voiceband
                                      signal transport on 64 kbit/s
                                      0 0 0 0 0 0 1 0     circuit
                                      transport
                                      0 0 0 0 0 1 0 0     high-quality
                                      audio signal transport
                                      0 0 0 0 0 1 0 1     video signal
                                      transport
                                      Ref.: ITU-T Q.2931

   CBRR       8002       1 octet     CBR Rate
                                      Bits
                                      8 7 6 5 4 3 2 1
                                      ---------------
                                      0 0 0 0 0 0 0 1       64 kbit/s
                                      0 0 0 0 0 1 0 0     1544 kbit/s
                                      0 0 0 0 0 1 0 1     6312 kbit/s
                                      0 0 0 0 0 1 1 0   32 064 kbit/s
                                      0 0 0 0 0 1 1 1   44 736 kbit/s
                                      0 0 0 0 1 0 0 0   97 728 kbit/s
                                      0 0 0 1 0 0 0 0     2048 kbit/s
                                      0 0 0 1 0 0 0 1     8448 kbit/s
                                      0 0 0 1 0 0 1 0   34 368 kbit/s
                                      0 0 0 1 0 0 1 1  139 264 kbit/s
                                      0 1 0 0 0 0 0 0   n x 64 kbit/s
                                      0 1 0 0 0 0 0 1    n x 8 kbit/s
                                      Ref.: ITU-T Q.2931

   MULT       See table              Multiplier, or n x 64k/8k/300
              in C.9                 Ref.: ITU-T Q.2931

   SCRI       8003       1 octet     Source Clock Frequency Recovery
                                      Method
                                      Bits
                                      8 7 6 5 4 3 2 1
                                      ---------------
                                      0 0 0 0 0 0 0 0     null
                                      0 0 0 0 0 0 0 1     SRTS
                                      0 0 0 0 0 0 1 0     ACM
                                      Ref.: ITU-T Q.2931

   ECM        8004       1 octet     Error Correction Method
                                      Bits
                                      8 7 6 5 4 3 2 1
                                      ---------------
                                      0 0 0 0 0 0 0 0     null
                                      0 0 0 0 0 0 0 1     FEC - Loss
                                      0 0 0 0 0 0 1 0     FEC - Delay
                                      Ref.: ITU-T Q.2931

   SDTB       8005       16-bit      Structured Data Transfer
                         integer     Blocksize
                                      Block size of SDT CBR service
                                      Ref.: ITU-T I.363.1

   PFCI       8006       8-bit       Partially filled cells identifier
                         integer     1-47
                                      Ref.: ITU-T I.363.1

C.9   Bearer capabilities

   The table entries referencing Recommendation Q.931 refer to the
   encoding in the bearer capability information element of Q.931, not
   to the low layer information element.

   PropertyID    Tag    Type      Value

   TMR           9001   1 octet   Transmission Medium
                                  Requirement (Q.763)
                                  Bits
                                  87654321
                                  --------
                                  00000000  speech
                                  00000001  spare
                                  00000010  64 kbit/s
                                  unrestricted

                                  00000011  3.1 kHz audio
                                  00000100  reserved for
                                  alternate speech (service
                                  2)/64 kbit/s unrestricted
                                  (service 1)
                                  00000101  reserved for
                                  alternate 64 kbit/s
                                  unrestricted (service
                                  1)/speech (service 2)
                                  00000110  64 kbit/s preferred

                                  The assigned codepoints
                                  listed below are all for
                                  unrestricted service.
                                  00000111  2 x 64 kbit/s
                                  00001000  384 kbit/s
                                  00001001  1536 kbit/s
                                  00001010  1920 kbit/s
                                  00001011
                                   through
                                  00001111  spare
                                  00010000
                                   through
                                  00101010:
                                     3 x 64 kbit/s through
                                    29 x 64 kbit/s
                                  except
                                  00010011  spare
                                  00100101  spare

                                  00101011
                                   through
                                  11111111  spare
                                  Ref.: ITU-T Q.763

   TMRSR         9002   1 octet   Transmission Medium
                                  Requirement Subrate
                                  0     unspecified
                                  1      8 kbit/s
                                  2     16 kbit/s
                                  3     32 kbit/s

   Contcheck     9003   Boolean   Continuity Check
                                  0     continuity check not
                                  required on this circuit
                                  1     continuity check
                                  required on this circuit
                                  Ref.: ITU-T Q.763

   ITC           9004   5 bits    Information Transfer
                                  Capability
                                  Bits
                                  5 4 3 2 1
                                  ---------
                                  0 0 0 0 0     Speech
                                  0 1 0 0 0     Unrestricted
                                  digital information
                                  0 1 0 0 1     Restricted
                                  digital information
                                  1 0 0 0 0     3.1 kHz audio
                                  1 0 0 0 1     Unrestricted
                                  digital information with
                                  tones/announcements
                                  1 1 0 0 0     Video
                                  All other values are
                                  reserved.
                                  Ref.: ITU-T Q.763

   TransMode     9005   2 bits    Transfer Mode
                                  Bits
                                  2 1
                                  ---
                                  0 0     Circuit mode
                                  1 0     Packet mode
                                  Ref.: ITU-T Q.931

   TransRate     9006   5 bits    Transfer Rate
                                  Bits
                                  5 4 3 2 1
                                  ---------
                                  0 0 0 0 0     This code shall
                                  be used for packet mode calls
                                  1 0 0 0 0      64 kbit/s
                                  1 0 0 0 1  2 x 64 kbit/s
                                  1 0 0 1 1     384 kbit/s
                                  1 0 1 0 1    1536 kbit/s
                                  1 0 1 1 1    1920 kbit/s
                                  1 1 0 0 0  Multirate (64
                                  kbit/s base rate)
                                  Ref.: ITU-T Q.931

   MULT          9007   7 bits    Rate Multiplier
                                  Any value from 2 to n
                                  (maximum number of B-
                                  channels)
                                  Ref.: ITU-T Q.931

   layer1prot    9008   5 bits    User Information Layer 1
                                  Protocol
                                  Bits
                                  5 4 3 2 1
                                  ---------
                                  0 0 0 0 1     ITU-T
                                  standardized rate adaption
                                  V.110 and X.30.
                                  0 0 0 1 0     Recommendation
                                  G.711 m-law
                                  0 0 0 1 1     Recommendation
                                  G.711 A-law
                                  0 0 1 0 0     Recommendation
                                  G.721 32 kbit/s ADPCM and
                                  Recommendation I.460
                                  0 0 1 0 1     Recommendations
                                  H.221 and H.242
                                  0 0 1 1 0     Recommendations
                                  H.223 and H.245
                                  0 0 1 1 1     Non-ITU-T
                                  standardized rate adaption.
                                  0 1 0 0 0     ITU-T
                                  standardized rate adaption
                                  V.120.
                                  0 1 0 0 1     ITU-T
                                  standardized rate adaption
                                  X.31 HDLC flag stuffing
                                  All other values are
                                  reserved.
                                  Ref.: ITU Recommendation
                                  Q.931

   syncasync     9009   Boolean   Synchronous/Asynchronous
                                  0     Synchronous data
                                  1     Asynchronous data
                                  Ref.: ITU-T Q.931

   negotiation   900A   Boolean   Negotiation
                                  0     In-band negotiation
                                  possible
                                  1     In-band negotiation not
                                  possible
                                  Ref.: ITU-T Q.931

   Userrate      900B   5 bits    User Rate
                                  Bits
                                  5 4 3 2 1

                                  ---------
                                  0 0 0 0 0     Rate is
                                  indicated by E-bits specified
                                  in Recommendation I.460 or
                                  may be negotiated in-band
                                  0 0 0 0 1     0.6 kbit/s
                                  Recommendations V.6 and X.1
                                  0 0 0 1 0     1.2 kbit/s
                                  Recommendation V.6
                                  0 0 0 1 1     2.4 kbit/s
                                  Recommendations V.6 and X.1
                                  0 0 1 0 0     3.6 kbit/s
                                  Recommendation V.6
                                  0 0 1 0 1     4.8 kbit/s
                                  Recommendations V.6 and X.1
                                  0 0 1 1 0     7.2 kbit/s
                                  Recommendation V.6
                                  0 0 1 1 1     8 kbit/s
                                  Recommendation I.460
                                  0 1 0 0 0     9.6 kbit/s
                                  Recommendations V.6 and X.1
                                  0 1 0 0 1     14.4 kbit/s
                                  Recommendation V.6
                                  0 1 0 1 0     16 kbit/s
                                  Recommendation I.460
                                  0 1 0 1 1     19.2 kbit/s
                                  Recommendation V.6
                                  0 1 1 0 0     32 kbit/s
                                  Recommendation I.460
                                  0 1 1 0 1     38.4 kbit/s
                                  Recommendation V.110
                                  0 1 1 1 0     48 kbit/s
                                  Recommendations V.6 and X.1
                                  0 1 1 1 1     56 kbit/s
                                  Recommendation V.6
                                  1 0 0 1 0     57.6 kbit/s
                                  Recommendation V.14 extended
                                  1 0 0 1 1     28.8 kbit/s
                                  Recommendation V.110
                                  1 0 1 0 0     24 kbit/s
                                  Recommendation V.110
                                  1 0 1 0 1     0.1345 kbit/s
                                  Recommendation X.1
                                  1 0 1 1 0     0.100 kbit/s
                                  Recommendation X.1
                                  1 0 1 1 1     0.075/1.2
                                  kbit/s Recommendations V.6
                                  and X.1

                                  1 1 0 0 0     1.2/0.075
                                  kbit/s Recommendations V.6
                                  and X.1
                                  1 1 0 0 1     0.050 kbit/s
                                  Recommendations V.6 and X.1
                                  1 1 0 1 0     0.075 kbit/s
                                  Recommendations V.6 and X.1
                                  1 1 0 1 1     0.110 kbit/s
                                  Recommendations V.6 and X.1
                                  1 1 1 0 0     0.150 kbit/s
                                  Recommendations V.6 and X.1
                                  1 1 1 0 1     0.200 kbit/s
                                  Recommendations V.6 and X.1
                                  1 1 1 1 0     0.300 kbit/s
                                  Recommendations V.6 and X.1
                                  1 1 1 1 1     12 kbit/s
                                  Recommendation V.6
                                  All other values are
                                  reserved.
                                  Ref.: ITU-T Q.931
   INTRATE       900C   2 bits    Intermediate Rate
                                  Bits
                                  2 1
                                  ---
                                  0 0     Not used
                                  0 1     8 kbit/s
                                  1 0     16 kbit/s
                                  1 1     32 kbit/s
                                  Ref.: ITU-T Q.931

   nictx         900D   Boolean   Network Independent Clock
                                  (NIC) on transmission
                                  0     Not required to send
                                  data with network independent
                                  clock
                                  1     Required to send data
                                  with network independent
                                  clock
                                  Ref.: ITU-T Q.931

   nicrx         900E   Boolean   Network independent clock
                                  (NIC) on reception
                                  0     Cannot accept data with
                                  network independent clock
                                  (i.e., sender does not support
                                  this optional procedure)
                                  1     Can accept data with
                                  network independent clock

                                  (i.e., sender does support
                                  this optional procedure)
                                  Ref.: ITU-T Q.931

   flowconttx    900F   Boolean   Flow Control on transmission
                                  (Tx)
                                  0     Not required to send
                                  data with flow control
                                  mechanism
                                  1     Required to send data
                                  with flow control mechanism
                                  Ref.: ITU-T Q.931

   flowcontrx    9010   Boolean   Flow control on reception
                                  (Rx)
                                  0     Cannot accept data with
                                  flow control mechanism (i.e.,
                                  sender does not support this
                                  optional procedure)
                                  1     Can accept data with
                                  flow control mechanism (i.e.,
                                  sender does support this
                                  optional procedure)
                                  Ref.: ITU-T Q.931

   rateadapthdr  9011   Boolean   Rate adaption header/no
                                  header
                                  0     Rate adaption header
                                  not included
                                  1     Rate adaption header
                                  included
                                  Ref.: ITU-T Q.931

   multiframe    9012   Boolean   Multiple frame establishment
                                  support in data link
                                  0     Multiple frame
                                  establishment not supported.
                                  Only UI frames allowed
                                  1     Multiple frame
                                  establishment supported
                                  Ref.: ITU-T Q.931

   OPMODE        9013   Boolean   Mode of operation
                                  0     Bit transparent mode of
                                  operation
                                  1     Protocol sensitive mode
                                  of operation
                                  Ref.: ITU-T Q.931

   llidnegot     9014   Boolean   Logical link identifier
                                  negotiation
                                  0     Default, LLI = 256 only
                                  1     Full protocol
                                  negotiation
                                  Ref.: ITU-T Q.931

   assign        9015   Boolean   Assignor/assignee
                                  0     Message originator is
                                  "default assignee"
                                  1     Message originator is
                                  "assignor only"
                                  Ref.: ITU-T Q.931

   inbandneg     9016   Boolean   In-band/out-band negotiation
                                  0     Negotiation is done
                                  with USER INFORMATION
                                  messages on a temporary
                                  signalling connection
                                  1     Negotiation is done in-
                                  band using logical link zero
                                  Ref.: ITU-T Q.931

   stopbits      9017   2 bits    Number of stop bits
                                  Bits
                                  2 1
                                  ---
                                  0 0     Not used
                                  0 1     1 bit
                                  1 0     1.5 bits
                                  1 1     2 bits
                                  Ref.: ITU-T Q.931

   databits      9018   2 bits    Number of data bits excluding
                                  parity bit if present
                                  Bits
                                  2 1
                                  ---
                                  0 0     Not used
                                  0 1     5 bits
                                  1 0     7 bits
                                  1 1     8 bits
                                  Ref.: ITU-T Q.931

   parity        9019   3 bits    Parity information
                                  Bits
                                  3 2 1

                                  ------
                                  0 0 0     Odd
                                  0 1 0     Even
                                  0 1 1     None
                                  1 0 0     Forced to 0
                                  1 0 1     Forced to 1
                                  All other values are
                                  reserved.
                                  Ref.: ITU-T Q.931

   duplexmode    901A   Boolean   Mode duplex
                                  0     Half duplex
                                  1     Full duplex
                                  Ref.: ITU-T Q.931

   modem         901B   6 bits    Modem Type
                                  Bits
                                  6 5 4 3 2 1
                                  -----------
                                  0 0 0 0 0 0 through
                                  0 0 0 1 0 1   National use
                                  0 1 0 0 0 1   Rec.  V.21
                                  0 1 0 0 1 0     Rec.  V.22
                                  0 1 0 0 1 1     Rec.  V.22 bis
                                  0 1 0 1 0 0     Rec.  V.23
                                  0 1 0 1 0 1     Rec.  V.26
                                  0 1 1 0 0 1     Rec.  V.26 bis
                                  0 1 0 1 1 1     Rec.  V.26 ter
                                  0 1 1 0 0 0     Rec.  V.27
                                  0 1 1 0 0 1     Rec.  V.27 bis
                                  0 1 1 0 1 0     Rec.  V.27 ter
                                  0 1 1 0 1 1     Rec.  V.29
                                  0 1 1 1 0 1     Rec.  V.32
                                  0 1 1 1 1 0     Rec.  V.34
                                  1 0 0 0 0 0  through
                                  1 0 1 1 1 1    National use
                                  1 1 0 0 0 0  through
                                  1 1 1 1 1 1    User specified
                                  Ref.: ITU-T Q.931

   layer2prot    901C   5 bits    User information layer 2
                                  protocol
                                  Bits
                                  5 4 3 2 1
                                  ---------
                                  0 0 0 1 0    Rec.  Q.921/I.441
                                  0 0 1 1 0    Rec.  X.25, link
                                  layer

                                  0 1 1 0 0    LAN logical link
                                  control (ISO/IEC 8802  2)
                                  All other values are
                                  reserved.
                                  Ref.: ITU-T Q.931

   layer3prot    901D   5 bits    User information layer 3
                                  protocol
                                  Bits
                                  5 4 3 2 1
                                  ---------
                                  0 0 0 1 0     ITU-T Q.931
                                  0 0 1 1 0     ITU-T X.25,
                                  packet layer
                                  0 1 0 1 1     ISO/IEC TR 9577
                                  (Protocol identification in
                                  the network layer)
                                  All other values are
                                  reserved.
                                  Ref.: ITU-T Q.931

   addlayer3prot 901E   Octet     Additional User Information
                                  layer 3 protocol
                                  Bits        Bits
                                  4 3 2 1     4 3 2 1
                                  -------     -------
                                  1 1 0 0     1 1 0 0
                                  Internet Protocol (RFC 791)
                                  (ISO/IEC TR 9577)
                                  1 1 0 0     1 1 1 1
                                  Point-to-point Protocol (RFC
                                  1661)
                                  Ref.: ITU-T Q.931

   DialledN      901F   30        Dialled Number
                        octets

   DiallingN     9020   30        Dialling Number
                        octets

   ECHOCI        9021             Not Used.  See H.248.1 E.13
                                  for an example of possible
                                  Echo Control properties.

   NCI           9022   1 octet   Nature of Connection
                                  Indicators
                                  Bits
                                  2 1     Satellite Indicator

                                  ---
                                  0 0     no satellite circuit
                                  in the connection
                                  0 1     one satellite circuit
                                  in the connection
                                  1 0     two satellite
                                  circuits in the connection
                                  1 1     spare

                                  Bits
                                  4 3     Continuity check
                                  ---     indicator
                                  0 0     continuity check not
                                  required
                                  0 1     continuity check
                                  required on this circuit
                                  1 0     continuity check
                                  performed on a previous
                                  circuit
                                  1 1     spare

                                  Bit
                                  5     Echo control device
                                  -     indicator
                                  0     outgoing echo control
                                  device not included
                                  1     outgoing echo control
                                  device included

                                  Bits
                                  8 7 6     Spare
                                  Ref.: ITU-T Q.763

   USI           9023   Octet     User Service Information
                        string    Ref.: ITU-T Q.763 Clause 3.57

C.10  AAL5 properties

   PropertyID Property    Type       Value
              tag

   FMSDU      A001        32-bit     Forward Maximum CPCS-SDU Size:
                          integer    Maximum CPCS-SDU size sent in the
                                     direction from the calling user to
                                     the called user.
                                     Ref.: ITU-T Q.2931

   BMSDU      A002        32-bit     Backwards Maximum CPCS-SDU Size:
                          integer    Maximum CPCS-SDU size sent in the
                                     direction from the called user to
                                     the calling user.
                                     Ref.: ITU-T Q.2931

   SSCS       See table   See table  See table in C.7
              in C.7      in C.7     Additional values:
                                     VPI/VCI

C.11  SDP equivalents

   PropertyID Property    Type   Value
              tag

   SDP_V      B001        String Protocol Version
                                  Ref.: RFC 2327

   SDP_O      B002        String Owner/creator and session ID
                                  Ref.: RFC 2327

   SDP_S      B003        String Session name
                                  Ref.: RFC 2327

   SDP_I      B004        String Session identifier
                                  Ref.: RFC 2327

   SDP_U      B005        String URI of descriptor
                                  Ref.: RFC 2327

   SDC_E      B006        String email address
                                  Ref.: RFC 2327

   SDP_P      B007        String phone number
                                  Ref.: RFC 2327

   SDP_C      B008        String Connection information
                                  Ref.: RFC 2327

   SDP_B      B009        String Bandwidth Information
                                  Ref.: RFC 2327

   SDP_Z      B00A        String Time zone adjustment
                                  Ref.: RFC 2327

   SDP_K      B00B        String Encryption Key
                                  Ref.: RFC 2327

   SDP_A      B00C        String Zero or more session attributes
                                  Ref.: RFC 2327

   SDP_T      B00D        String Active Session Time
                                  Ref.: RFC 2327

   SDP_R      B00E        String Zero or more repeat times
                                  Reference: RFC 2327

   SDP_M      B00F        String Media type, port, transport and format
                                  Ref.: RFC 2327

C.12  H.245

   PropertyID Property   Type     Value
              tag

   OLC        C001       Octet    The value of H.245
                                   OpenLogicalChannel structure.
                         string   Ref.: ITU-T H.245

   OLCack     C002       Octet    The value of H.245
                         string   OpenLogicalChannelAck structure.
                                   Ref.: ITU-T H.245

   OLCcnf     C003       Octet    The value of H.245
                         string   OpenLogicalChannelConfirm structure.
                                   Ref.: ITU-T H.245

   OLCrej     C004       Octet    The value of H.245
                         string   OpenLogicalChannelReject structure.
                                   Ref.: ITU-T H.245

   CLC        C005       Octet    The value of H.245
                         string   CloseLogicalChannel structure.
                                   Ref.: ITU-T H.245

   CLCack     C006       Octet    The value of H.245
                         string   CloseLogicalChannelAck structure.
                                   Ref.: ITU-T H.245

ANNEX D - Transport over IP

D.1   Transport over IP/UDP using Application Level Framing (ALF)

   Protocol messages defined in this RFC may be transmitted over UDP.
   When no port is provided by the peer (see 7.2.8), commands should be
   sent to the default port number: 2944 for text-encoded operation, or
   2945 for binary-encoded operation.  Responses must be sent to the
   address and port from which the corresponding commands were sent.

   ALF is a set of techniques that allows an application, as opposed to
   a stack, to affect how messages are sent to the other side.  A
   typical ALF technique is to allow an application to change the order
   of messages sent when there is a queue after it has queued them.
   There is no formal specification for ALF.  The procedures in Annex
   D.1 contain a minimum suggested set of ALF behaviours

   Implementors using IP/UDP with ALF should be aware of the
   restrictions of the MTU on the maximum message size.

D.1.1 Providing At-Most-Once functionality

   Messages, being carried over UDP, may be subject to losses.  In the
   absence of a timely response, commands are repeated.  Most commands
   are not idempotent.  The state of the MG would become unpredictable
   if, for example, Add commands were executed several times.  The
   transmission procedures shall thus provide an "At-Most-Once"
   functionality.

   Peer protocol entities are expected to keep in memory a list of the
   responses that they sent to recent transactions and a list of the
   transactions that are currently outstanding.  The transaction
   identifier of each incoming message is compared to the transaction
   identifiers of the recent responses sent to the same MId.  If a match
   is found, the entity does not execute the transaction, but simply
   repeats the response.  If no match is found, the message will be
   compared to the list of currently outstanding transactions.  If a
   match is found in that list, indicating a duplicate transaction, the
   entity does not execute the transaction (see D.1.4 for procedures on
   sending TransactionPending).

   The procedure uses a long timer value, noted LONG-TIMER in the
   following.  The timer should be set larger than the maximum duration
   of a transaction, which should take into account the maximum number

   of repetitions, the maximum value of the repetition timer and the
   maximum propagation delay of a packet in the network.  A suggested
   value is 30 seconds.

   The copy of the responses may be destroyed either LONG-TIMER seconds
   after the response is issued, or when the entity receives a
   confirmation that the response has been received, through the
   "Response Acknowledgement parameter".  For transactions that are
   acknowledged through this parameter, the entity shall keep a copy of
   the transaction-id for LONG-TIMER seconds after the response is
   issued, in order to detect and ignore duplicate copies of the
   transaction request that could be produced by the network.

D.1.2 Transaction identifiers and three-way handshake

D.1.2.1  Transaction identifiers

   Transaction identifiers are 32-bit integer numbers.  A Media Gateway
   Controller may decide to use a specific number space for each of the
   MGs that they manage, or to use the same number space for all MGs
   that belong to some arbitrary group.  MGCs may decide to share the
   load of managing a large MG between several independent processes.
   These processes will share the same transaction number space.  There
   are multiple possible implementations of this sharing, such as having
   a centralized allocation of transaction identifiers, or
   pre-allocating non-overlapping ranges of identifiers to different
   processes.  The implementations shall guarantee that unique
   transaction identifiers are allocated to all transactions that
   originate from a logical MGC (identical mId).  MGs can simply detect
   duplicate transactions by looking at the transaction identifier and
   mId only.

D.1.2.2  Three-way handshake

   The TransactionResponse Acknowledgement parameter can be found in any
   message.  It carries a set of "confirmed transaction-id ranges".
   Entities may choose to delete the copies of the responses to
   transactions whose id is included in "confirmed transaction-id
   ranges" received in the transaction response messages.  They should
   silently discard further commands when the transaction-id falls
   within these ranges.

   The "confirmed transaction-id ranges" values shall not be used if
   more than LONG-TIMER seconds have elapsed since the MG issued its
   last response to that MGC, or when a MG resumes operation.  In this
   situation, transactions should be accepted and processed, without any
   test on the transaction-id.

   Messages that carry the "Transaction Response Acknowledgement"
   parameter may be transmitted in any order.  The entity shall retain
   the "confirmed transaction-id ranges" received for LONG-TIMER
   seconds.

   In the binary encoding, if only the firstAck is present in a response
   acknowledgement (see A.2), only one transaction is acknowledged.  If
   both firstAck and lastAck are present, then the range of transactions
   from firstAck to lastAck is acknowledged.  In the text encoding, a
   horizontal dash is used to indicate a range of transactions being
   acknowledged (see B.2).

D.1.3 Computing retransmission timers

   It is the responsibility of the requesting entity to provide suitable
   timeouts for all outstanding transactions, and to retry transactions
   when timeouts have been exceeded.  Furthermore, when repeated
   transactions fail to be acknowledged, it is the responsibility of the
   requesting entity to seek redundant services and/or clear existing or
   pending connections.

   The specification purposely avoids specifying any value for the
   retransmission timers.  These values are typically network dependent.
   The retransmission timers should normally estimate the timer value by
   measuring the time spent between the sending of a command and the
   return of a response.  Implementations SHALL ensure that the
   algorithm used to calculate retransmission timing performs an
   exponentially increasing backoff of the retransmission timeout for
   each retransmission or repetition after the first one.

     NOTE - One possibility is to use the algorithm implemented in
     TCP-IP, which uses two variables:

   -  The average acknowledgement delay (AAD), estimated through an
      exponentially smoothed average of the observed delays.

   -  The average deviation (ADEV), estimated through an exponentially
      smoothed average of the absolute value of the difference between
      the observed delay and the current average.  The retransmission
      timer, in TCP, is set to the sum of the average delay plus N times
      the average deviation.  The maximum value of the timer should
      however be bounded for the protocol defined in this
      RFC, in order to guarantee that no repeated packet
      would be received by the gateways after LONG-TIMER seconds.  A
      suggested maximum value is 4 seconds.

   After any retransmission, the entity SHOULD do the following:

   -  It should double the estimated value of the average delay, AAD.

   -  It should compute a random value, uniformly distributed between
      0.5 AAD and AAD.

   -  It should set the retransmission timer to the sum of that random
      value and N times the average deviation.

   This procedure has two effects.  Because it includes an exponentially
   increasing component, it will automatically slow down the stream of
   messages in case of congestion.  Because it includes a random
   component, it will break the potential synchronization between
   notifications triggered by the same external event.

D.1.4 Provisional responses

   Executing some transactions may require a long time.  Long execution
   times may interact with the timer-based retransmission procedure.
   This may result either in an inordinate number of retransmissions, or
   in timer values that become too long to be efficient.  Entities that
   can predict that a transaction will require a long execution time may
   send a provisional response, "Transaction Pending".  They SHOULD send
   this response if they receive a repetition of a transaction that is
   still being executed.

   Entities that receive a Transaction Pending shall switch to a
   different repetition timer for repeating requests.  The root
   Termination has a property (ProvisionalResponseTimerValue), which can
   be set to the requested maximum number of milliseconds between
   receipt of a command and transmission of the TransactionPending
   response.  Upon receipt of a final response following receipt of
   provisional responses, an immediate confirmation shall be sent, and
   normal repetition timers shall be used thereafter.  An entity that
   sends a provisional response, SHALL include the immAckRequired field
   in the ensuing final response, indicating that an immediate
   confirmation is expected.  Receipt of a Transaction Pending after
   receipt of a reply shall be ignored.

D.1.5 Repeating Requests, Responses and Acknowledgements

   The protocol is organized as a set of transactions, each of which is
   composed of a request and a response, commonly referred to as an
   acknowledgement.  The protocol messages, being carried over UDP, may
   be subject to losses.  In the absence of a timely response,
   transactions are repeated.  Entities are expected to keep in memory a

   list of the responses that they sent to recent transactions, i.e., a
   list of all the responses they sent over the last LONG-TIMER seconds,
   and a list of the transactions that are currently being executed.

   The repetition mechanism is used to guard against three types of
   possible errors:

   -  transmission errors, when for example a packet is lost due to
      noise on a line or congestion in a queue;

   -  component failure, when for example an interface to a entity
      becomes unavailable;

   -  entity failure, when for example an entire entity becomes
      unavailable.

   The entities should be able to derive from the past history an
   estimate of the packet loss rate due to transmission errors.  In a
   properly configured system, this loss rate should be kept very low,
   typically less than 1%.  If a Media Gateway Controller or a Media
   Gateway has to repeat a message more than a few times, it is very
   legitimate to assume that something else than a transmission error is
   occurring.   For example, given a loss rate of 1%, the probability
   that five consecutive transmission attempts fail is 1 in 100 billion,
   an event that should occur less than once every 10 days for a Media
   Gateway Controller that processes 1000 transactions per second.
   (Indeed, the number of repetition that is considered excessive should
   be a function of the prevailing packet loss rate.)  We should note
   that the "suspicion threshold", which we will call "Max1", is
   normally lower than the "disconnection threshold", which should be
   set to a larger value.

   A classic retransmission algorithm would simply count the number of
   successive repetitions, and conclude that the association is broken
   after retransmitting the packet an excessive number of times
   (typically between 7 and 11 times.)  In order to account for the
   possibility of an undetected or in  progress "failover", we modify
   the classic algorithm so that if the Media Gateway receives a valid
   ServiceChange message announcing a failover, it will start
   transmitting outstanding commands to that new MGC.  Responses to
   commands are still transmitted to the source address of the command.

   In order to automatically adapt to network load, this RFC specifies
   exponentially increasing timers.  If the initial timer is set to 200
   milliseconds, the loss of a fifth retransmission will be detected
   after about 6 seconds.  This is probably an acceptable waiting delay
   to detect a failover.  The repetitions should continue after that
   delay not only in order to perhaps overcome a transient connectivity

   problem, but also in order to allow some more time for the execution
   of a failover  (waiting a total delay of 30 seconds is probably
   acceptable).

   It is, however, important that the maximum delay of retransmissions
   be bounded.  Prior to any retransmission, it is checked that the time
   elapsed since the sending of the initial datagram is no greater than
   T-MAX.  If more than T-MAX time has elapsed, the MG concludes that
   the MGC has failed, and it begins its recovery process as described
   in section 11.5.  If the MG retries to connect to the current MGC it
   shall use a ServiceChange with ServiceChangeMethod set to
   Disconnected so that the new MGC will be aware that the MG lost one
   or more transactions.  The value T-MAX is related to the LONG-TIMER
   value: the LONG-TIMER value is obtained by adding to T  MAX the
   maximum propagation delay in the network.

D.2   Using TCP

   Protocol messages as defined in this RFC may be transmitted over TCP.
   When no port is specified by the other side (see 7.2.8), the commands
   should be sent to the default port.  The defined protocol has
   messages as the unit of transfer, while TCP is a stream-oriented
   protocol.  TPKT, according to RFC 1006, SHALL be used to delineate
   messages within the TCP stream.

   In a transaction-oriented protocol, there are still ways for
   transaction requests or responses to be lost.  As such, it is
   recommended that entities using TCP transport implement application
   level timers for each request and each response, similar to those
   specified for application level framing over UDP.

D.2.1 Providing the At-Most-Once functionality

   Messages, being carried over TCP, are not subject to transport
   losses, but loss of a transaction request or its reply may
   nonetheless be noted in real implementations.  In the absence of a
   timely response, commands are repeated.  Most commands are not
   idempotent.  The state of the MG would become unpredictable if, for
   example, Add commands were executed several times.

   To guard against such losses, it is recommended that entities follow
   the procedures in D.1.1.

D.2.2 Transaction identifiers and three-way handshake

   For the same reasons, it is possible that transaction replies may be
   lost even with a reliable delivery protocol such as TCP.  It is
   recommended that entities follow the procedures in D.1.2.2.

D.2.3 Computing retransmission timers

   With reliable delivery, the incidence of loss of a transaction
   request or reply is expected to be very low.  Therefore, only simple
   timer mechanisms are required.  Exponential back-off algorithms
   should not be necessary, although they could be employed where, as in
   an MGC, the code to do so is already required, since MGCs must
   implement ALF/UDP as well as TCP.

D.2.4 Provisional responses

   As with UDP, executing some transactions may require a long time.
   Entities that can predict that a transaction will require a long
   execution time may send a provisional response, "Transaction
   Pending".  They should send this response if they receive a
   repetition of a transaction that is still being executed.

   Entities that receive a Transaction Pending shall switch to a longer
   repetition timer for that transaction.

   Entities shall retain Transactions and replies until they are
   confirmed.  The basic procedure of D.1.4 should be followed, but
   simple timer values should be sufficient.  There is no need to send
   an immediate confirmation upon receipt of a final response.

D.2.5 Ordering of commands

   TCP provides ordered delivery of transactions.  No special procedures
   are required.  It should be noted that ALF/UDP allows sending entity
   to modify its behaviour under congestion, and in particular, could
   reorder transactions when congestion is encountered.  TCP could not
   achieve the same results.

ANNEX E - Basic packages

   This annex contains definitions of some packages for use with
   Recommendation H.248.1.

E.1   Generic

   PackageID: g (0x0001)
   Version: 1
   Extends: None

   Description:
      Generic package for commonly encountered items.

E.1.1 Properties

   None.

E.1.2 Events

   Cause

      EventID: cause (0x0001)
      Generic error event

      EventsDescriptor parameters:  None

      ObservedEvents Descriptor Parameters:

         General Cause
         ParameterID: Generalcause (0x0001)

            This parameter groups the failures into six groups, which
            the MGC may act upon.

            Type: enumeration

            Possible values:
                     "NR" Normal Release (0x0001)
                     "UR" Unavailable Resources (0x0002)
                     "FT" Failure, Temporary (0x0003)
                     "FP" Failure, Permanent (0x0004)
                     "IW" Interworking Error (0x0005)
                     "UN" Unsupported (0x0006)

         Failure Cause
         ParameterID: Failurecause (0x0002)

            Possible values:  OCTET STRING

            Description: The Failure Cause is the value generated by the
            Released equipment, i.e., a released network connection.
            The concerned value is defined in the appropriate bearer
            control protocol.

   Signal Completion

      EventID: sc (0x0002)

      Indicates the termination of a signal for which the
      notifyCompletion parameter was set to enable reporting of a
      completion event.  For further procedural description, see 7.1.1,
      7.1.17 and 7.2.7.

      EventsDescriptor parameters:  None

      ObservedEvents Descriptor parameters:

         Signal Identity
         ParameterID: SigID (0x0001)

            This parameter identifies the signal which has terminated.
            For a signal that is contained in a signal list, the signal
            list identity parameter should also be returned indicating
            the appropriate list.

            Type: Binary: octet (string), Text: string

            Possible values: a signal which has terminated.  A signal
            shall be identified using the pkgdName syntax without
            wildcarding.

         Termination Method
         ParameterID: Meth (0x0002)

            Indicates the means by which the signal terminated.

            Type: enumeration

            Possible values:
               "TO" (0x0001) Signal timed out or otherwise completed on
               its own
               "EV" (0x0002) Interrupted by event
               "SD" (0x0003) Halted by new Signals descriptor
               "NC" (0x0004) Not completed, other cause

         Signal List ID
         ParameterID:  SLID (0x0003)

            Indicates to which signal list a signal belongs.  The
            SignalList ID is only returned in cases where the signal
            resides in a signal list.

            Type: integer

            Possible values: any integer

E.1.3 Signals

   None.

E.1.4 Statistics

   None.

E.2   Base Root Package

   PackageID: root (0x0002)
   Version: 1
   Extends: None

   Description:
      This package defines Gateway wide properties.

E.2.1 Properties

   MaxNrOfContexts
   PropertyID: maxNumberOfContexts (0x0001)

      The value of this property gives the maximum number of contexts
      that can exist at any time.  The NULL context is not included in
      this number.

      Type: double

      Possible values: 1 and up

      Defined in: TerminationState

      Characteristics: read only

   MaxTerminationsPerContext
   PropertyID: maxTerminationsPerContext (0x0002)

      The maximum number of allowed terminations in a context, see 6.1

      Type: integer

      Possible values: any integer

      Defined in: TerminationState

      Characteristics: read only

   normalMGExecutionTime
   PropertyId: normalMGExecutionTime (0x0003)

      Settable by the MGC to indicate the interval within which the MGC
      expects a response to any transaction from the MG (exclusive of
      network delay)

      Type: integer

      Possible values: any integer, represents milliseconds

      Defined in: TerminationState

      Characteristics: read / write

   normalMGCExecutionTime
   PropertyId: normalMGCExecutionTime (0x0004)

      Settable by the MGC to indicate the interval within which the MG
      should expects a response to any transaction from the MGC
      (exclusive of network delay)

      Type: integer

      Possible values: any integer, represents milliseconds

      Defined in: TerminationState

      Characteristics: read / write

   MGProvisionalResponseTimerValue
   PropertyId: MGProvisionalResponseTimerValue (0x0005)

      Indicates the time within which the MGC should expect a Pending
      Response from the MG if a Transaction cannot be completed.

      Initially set to normalMGExecutionTime plus network delay, but may
      be lowered.

      Type: Integer

      Possible Values: any integer, represents milliseconds

      Defined in: TerminationState

      Characteristics: read / write

   MGCProvisionalResponseTimerValue
   PropertyId: MGCProvisionalResponseTimerValue (0x0006)

      Indicates the time within which the MG should expect a Pending
      Response from the MGC if a Transaction cannot be completed.
      Initially set to normalMGCExecutionTime plus network delay, but
      may be lowered.

      Type: Integer

      Possible Values: any integer, represents milliseconds

      Defined in: TerminationState

      Characteristics: read / write

E.2.2 Events

   None.

E.2.3 Signals

   None.

E.2.4 Statistics

   None.

E.2.5 Procedures

   None.

E.3   Tone Generator Package

   PackageID: tonegen (0x0003)
   Version: 1
   Extends: None

   Description:

      This package defines signals to generate audio tones.  This
      package does not specify parameter values.  It is intended to be
      extendable.  Generally, tones are defined as an individual signal
      with a parameter, ind, representing "interdigit" time delay, and a
      tone id to be used with playtones.  A tone id should be kept
      consistent with any tone generation for the same tone.  MGs are
      expected to be provisioned with the characteristics of appropriate
      tones for the country in which the MG is located.

   Designed to be extended only.

E.3.1 Properties

   None.

E.3.2 Events

   None.

E.3.3 Signals

   Play tone
   SignalID: pt (0x0001)

      Plays audio tone over an audio channel

      Signal Type: Brief

      Duration: Provisioned

      Additional parameters:

         Tone id list
         ParameterID: tl (0x0001)

            Type: list of tone ids

            List of tones to be played in sequence.  The list SHALL
            contain one or more tone ids.

         Inter signal duration
         ParameterID: ind (0x0002)

            Type: integer

            Timeout between two consecutive tones in milliseconds

   No tone ids are specified in this package.  Packages that extend this
   package can add possible values for tone id as well as adding
   individual tone signals.

E.3.4 Statistics

   None.

E.3.5 Procedures

   None.

E.4   Tone Detection Package

   PackageID: tonedet (0x0004)
   Version: 1
   Extends: None

   This Package defines events for audio tone detection.  Tones are
   selected by name (tone id).  MGs are expected to be provisioned with
   the characteristics of appropriate tones for the country in which the
   MG is located.

   Designed to be extended only:
      This package does not specify parameter values.  It is intended to
      be extendable.

E.4.1 Properties

   None.

E.4.2 Events

   Start tone detected
   EventID: std, 0x0001

      Detects the start of a tone.  The characteristics of positive tone
      detection are implementation dependent.

      EventsDescriptor parameters:

         Tone id list
         ParameterID: tl (0x0001)

            Type: list of tone ids

            Possible values: The only tone id defined in this package is
            "wild card" which is "*" in text encoding and 0x0000 in
            binary.  Extensions to this package would add possible
            values for tone id.  If tl is "wild card", any tone id is
            detected.

         ObservedEventsDescriptor parameters:

         Tone id
         ParameterID: tid (0x0003)

            Type: enumeration

            Possible values: "wildcard" as defined above is the only
            value defined in this package.  Extensions to this package
            would add additional possible values for tone id.

         End tone detected
         EventID: etd, 0x0002

         Detects the end of a tone.

         EventDescriptor parameters:

            Tone id list
            ParameterID: tl (0x0001)

               Type: enumeration or list of enumerated types

               Possible values: No possible values are specified in this
               package.  Extensions to this package would add possible
               values for tone id.

         ObservedEventsDescriptor parameters:

            Tone id
            ParameterID: tid (0x0003)

               Type: enumeration

               Possible values: "wildcard" as defined above is the only
               value defined in this package.  Extensions to this
               package would add possible values for tone id.

            Duration
            ParameterId: dur (0x0002)

               Type: integer, in milliseconds

               This parameter contains the duration of the tone from
               first detection until it stopped.

   Long tone detected
   EventID: ltd, 0x0003

      Detects that a tone has been playing for at least a certain amount
      of time.

      EventDescriptor parameters:

         Tone id list
         ParameterID: tl (0x0001)

            Type: enumeration or list

            Possible values: "wildcard" as defined above is the only
            value defined in this package.  Extensions to this package
            would add possible values for tone id.

         Duration
         ParameterID: dur (0x0002)

            Type: integer, duration to test against

            Possible values: any legal integer, expressed in
            milliseconds

      ObservedEventsDescriptor parameters:

         Tone id
         ParameterID: tid (0x0003)

            Type: Enumeration

            Possible values: No possible values are specified in this
            package.  Extensions to this package would add possible
            values for tone id.

E.4.3 Signals

   None.

E.4.4 Statistics

   None.

E.4.5 Procedures

   None.

E.5   Basic DTMF Generator Package

   PackageID: dg (0x0005)
   Version: 1
   Extends: tonegen version 1

   This package defines the basic DTMF tones as signals and extends the
   allowed values of parameter tl of playtone in tonegen.

E.5.1 Properties

   None.

E.5.2 Events

   None.

E.5.3 Signals

   DTMF character 0
   SignalID: d0 (0x0010)

      Generate DTMF 0 tone.  The physical characteristic of DTMF 0 is
      defined in the gateway.

      Signal Type: Brief

      Duration: Provisioned

      Additional parameters:

         None.

   Additional values:

      d0 (0x0010) is defined as a tone id for playtone

   The other DTMF characters are specified in exactly the same way.  A
   table with all signal names and signal IDs is included.  Note that
   each DTMF character is defined as both a signal and a tone id, thus
   extending the basic tone generation package.  Also note that DTMF
   SignalIds are different from the names used in a digit map.

                     Signal name     Signal ID/Tone id

                    DTMF character 0    d0 (0x0010)
                    DTMF character 1    d1 (0x0011)
                    DTMF character 2    d2 (0x0012)
                    DTMF character 3    d3 (0x0013)
                    DTMF character 4    d4 (0x0014)
                    DTMF character 5    d5 (0x0015)
                    DTMF character 6    d6 (0x0016)
                    DTMF character 7    d7 (0x0017)
                    DTMF character 8    d8 (0x0018)
                    DTMF character 9    d9 (0x0019)
                    DTMF character *    ds (0x0020)
                    DTMF character #    do (0x0021)
                    DTMF character A    da (0x001a)
                    DTMF character B    db (0x001b)
                    DTMF character C    dc (0x001c)
                    DTMF character D    dd (0x001d)

E.5.4 Statistics

   None.

E.5.5 Procedures

   None.

E.6   DTMF detection Package

   PackageID: dd (0x0006)
   Version: 1
   Extends: tonedet version 1

   This package defines the basic DTMF tones detection.  This Package
   extends the possible values of tone id in the "start tone detected"
   "end tone detected" and "long tone detected" events.

   Additional tone id values are all tone ids described in package dg
   (basic DTMF generator package).

   The following table maps DTMF events to digit map symbols as
   described in 7.1.14.

                           DTMF Event Symbol

                           d0   "0"
                           d1   "1"
                           d2   "2"

                           d3   "3"
                           d4   "4"
                           d5   "5"
                           d6   "6"
                           d7   "7"
                           d8   "8"
                           d9   "9"
                           da   "A" or "a"
                           db   "B" or "b"
                           dc   "C" or "c"
                           dd   "D" or "d"
                           ds   "E" or "e"
                           do   "F" or "f"

E.6.1 Properties

   None.

E.6.2 Events

   DTMF digits

      EventIds are defined with the same names as the SignalIds defined
      in the table found in E.5.3.

   DigitMap Completion Event
   EventID: ce, 0x0004

      Generated when a digit map completes as described in 7.1.14.

      EventsDescriptor parameters: None.

      ObservedEventsDescriptor parameters:

         DigitString
         ParameterID: ds (0x0001)

            Type: string of digit map symbols (possibly empty) returned
            as a quotedString

            Possible values: a sequence of the characters "0" through
            "9", "A" through "F", and the long duration modifier "Z".

            Description: the portion of the current dial string as
            described in 7.1.14 which matched part or all of an
            alternative event sequence specified in the digit map.

         Termination Method
         ParameterID: Meth (0x0003)

            Type: enumeration

            Possible values:

               "UM" (0x0001) Unambiguous match

               "PM" (0x0002) Partial match, completion by timer expiry
               or unmatched event

               "FM" (0x0003) Full match, completion by timer expiry or
               unmatched event

            Description: indicates the reason for generation of the
            event.  See the procedures in 7.1.14.

E.6.3 Signals

   None.

E.6.4 Statistics

   None.

E.6.5 Procedures

   Digit map processing is activated only if an events descriptor is
   activated that contains a digit map completion event as defined in
   Section E.6.2 and that digit map completion event contains an eventDM
   field in the requested actions as defined in Section 7.1.9.  Other
   parameters such as KeepActive or embedded events of signals
   descriptors may also be present in the events descriptor and do not
   affect the activation of digit map processing.

E.7   Call Progress Tones Generator Package

   PackageID: cg, 0x0007
   Version: 1
   Extends: tonegen version 1

   This package defines the basic call progress tones as signals and
   extends the allowed values of the tl parameter of playtone in
   tonegen.

E.7.1 Properties

   None.

E.7.2 Events

   None.

E.7.3 Signals

   Dial Tone
   SignalID: dt (0x0030)

      Generate dial tone.  The physical characteristic of dial tone is
      available in the gateway.

      Signal Type: TimeOut

      Duration: Provisioned

      Additional parameters:

         None.

   Additional values:

      dt (0x0030) is defined as a tone id for playtone

   The other tones of this package are defined in exactly the same way.
   A table with all signal names and signal IDs is included.  Note that
   each tone is defined as both a signal and a tone id, thus extending
   the basic tone generation package.

     Signal Name                 Signal ID/tone id

     Dial Tone                   dt (0x0030)
     Ringing Tone                rt (0x0031)
     Busy Tone                   bt (0x0032)
     Congestion Tone             ct (0x0033)
     Special Information Tone    sit(0x0034)
     Warning Tone                wt (0x0035)
     Payphone Recognition Tone   prt (0x0036)
     Call Waiting Tone           cw (0x0037)
     Caller Waiting Tone         cr (0x0038)

E.7.4 Statistics

   None.

E.7.5 Procedures

      NOTE - The required set of tone ids corresponds to those defined
      in Recommendation E.180/Q.35.  See Recommendation E.180/Q.35 for
      definition of the meanings of these tones.


E.8   Call Progress Tones Detection Package

   PackageID: cd (0x0008)
   Version: 1
   Extends: tonedet version 1

   This package defines the basic call progress detection tones.  This
   package extends the possible values of tone id in the "start tone
   detected", "end tone detected" and "long tone detected" events.

   Additional values

      toneID values are defined for start tone detected, end tone
      detected and long tone detected with the same values as those in
      package cg (call progress tones generation package).

   The required set of tone ids corresponds to Recommendation
   E.180/Q.35.  See Recommendation E.180/Q.35 for definition of the
   meanings of these tones.

E.8.1 Properties

   None.

E.8.2 Events

   Events are defined as in the call progress tones generator package
   (cg) for the tones listed in the table of E.7.3.

E.8.3 Signals

   None.

E.8.4 Statistics

   None.

E.8.5 Procedures

   None.

E.9   Analog Line Supervision Package

   PackageID: al, 0x0009
   Version: 1
   Extends: None

   This package defines events and signals for an analog line.

   E.9.1 Properties

   None.

E.9.2 Events

   onhook
   EventID: on (0x0004)

      Detects handset going on hook.  Whenever an events descriptor is
      activated that requests monitoring for an on-hook event and the
      line is already on-hook, then the MG shall behave according to the
      setting of the "strict" parameter.

      EventDescriptor parameters:

         Strict Transition
         ParameterID: strict (0x0001)

            Type: enumeration

            Possible values: "exact" (0x00), "state" (0x01), "failWrong"
            (0x02)

              "exact" means that only an actual hook state transition to
              on-hook is to be recognized;

              "state" means that the event is to be recognized either if
              the hook state transition is detected or if the hook state
              is already on-hook;

              "failWrong" means that if the hook state is already
              on-hook, the command fails and an error is reported.

      ObservedEventsDescriptor parameters:

         Initial State
         ParameterID: init (0x0002)

            Type: Boolean

            Possible values:

               "True" means that the event was reported because the line
               was already on-hook when the events descriptor containing
               this event was activated;

               "False" means that the event represents an actual state
               transition to on-hook.

   offhook
   EventID: of (0x0005)

      Detects handset going off hook.  Whenever an events descriptor is
      activated that requests monitoring for an off-hook event and the
      line is already off-hook, then the MG shall behave according to
      the setting of the "strict" parameter.

      EventDescriptor parameters:

         Strict Transition
         ParameterID: strict (0x0001)

            Type: enumeration

            Possible values: "exact" (0x00), "state" (0x01), "failWrong"
            (0x02)

               "exact" means that only an actual hook state transition
               to off-hook is to be recognized;

               "state" means that the event is to be recognized either
               if the hook state transition is detected or if the hook
               state is already off-hook;

               "failWrong" means that if the hook state is already off-
               hook, the command fails and an error is reported.

      ObservedEventsDescriptor parameters

         Initial State
         ParameterID: init (0x0002)

            Type: Boolean

            Possible values:

               "True" means that the event was reported because the line
               was already off-hook when the events descriptor
               containing this event was activated;

               "False" means that the event represents an actual state
               transition to off-hook.

   flashhook
   EventID: fl, 0x0006

      Detects handset flash.  A flash occurs when an onhook is followed
      by an offhook between a minimum and maximum duration.

      EventDescriptor parameters:

         Minimum duration
         ParameterID: mindur (0x0004)

            Type: integer in milliseconds

            Default value is provisioned.

         Maximum duration
         ParameterID: maxdur (0x0005)

            Type: integer in milliseconds

            Default value is provisioned.

      ObservedEventsDescriptor parameters:

         None

E.9.3 Signals

   ring
   SignalID: ri, 0x0002

      Applies ringing on the line

      Signal Type: TimeOut

      Duration: Provisioned

      Additional parameters:

         Cadence
         ParameterID: cad (0x0006)

            Type: list of integers representing durations of alternating
            on and off segments, constituting a complete ringing cycle
            starting with an on.  Units in milliseconds

            Default is fixed or provisioned.  Restricted function MGs
            may ignore cadence values they are incapable of generating.

         Frequency
         ParameterID: freq (0x0007)

            Type: integer in Hz

            Default is fixed or provisioned.  Restricted function MGs
            may ignore frequency values they are incapable of
            generating.

E.9.4 Statistics

   None.

E.9.5 Procedures

   If the MGC sets an EventsDescriptor containing a hook state
   transition event (on-hook or off-hook) with the "strict" (0x0001)
   parameter set to "failWrong", and the hook state is already what the
   transition implies, the execution of the command containing that
   EventsDescriptor fails.  The MG SHALL include error code 540
   "Unexpected initial hook state" in its reponse.

E.9.6 Error code

   This package defines a new error code:

      540 - Unexpected initial hook state

   The procedure for use of this code is given in E.9.5.

E.10  Basic Continuity Package

   PackageID: ct (0x000a)
   Version: 1
   Extends: None

   This package defines events and signals for continuity test.  The
   continuity test includes provision of either a loopback or
   transceiver functionality.

E.10.1   Properties

   None.

E.10.2   Events

   Completion
   EventID: cmp, 0x0005

      This event detects test completion of continuity test.

      EventDescriptor parameters

         None.

      ObservedEventsDescriptor parameters

         Result
         ParameterID: res (0x0008)

            Type: enumeration

            Possible values: success (0x0001), failure (0x0000)

E.10.3   Signals

   Continuity test
   SignalID: ct (0x0003)

      Initiates sending of continuity test tone on the termination to
      which it is applied.

      Signal Type: TimeOut

      Default value is provisioned

      Additional parameters:

         None.

   Respond
   SignalID: rsp (0x0004)

      The signal is used to respond to a continuity test.  See E.10.5
      for further explanation.

      Signal Type: On/Off

      Default duration is provisioned

      Additional parameters:

         None.

E.10.4   Statistics

   None.

E.10.5   Procedures

   When a MGC wants to initiate a continuity test, it sends a command to
   the MG containing:

   -  a signals descriptor with the ct signal; and

   -  an events descriptor containing the cmp event.

   Upon reception of a command containing the ct signal and cmp event,
   the MG initiates the continuity test tone for the specified
   Termination.  If the return tone is detected and any other required
   conditions are satisfied before the signal times out, the cmp event
   shall be generated with the value of the result parameter equal to
   success.  In all other cases, the cmp event shall be generated with
   the value of the result parameter equal to failure.

   When a MGC wants the MG to respond to a continuity test, it sends a
   command to the MG containing a signals descriptor with the rsp
   signal.  Upon reception of a command with the rsp signal, the MG
   either applies a loopback or (for 2-wire circuits) awaits reception
   of a continuity test tone.  In the loopback case, any incoming
   information shall be reflected back as outgoing information.  In the
   2-wire case, any time the appropriate test tone is received, the
   appropriate response tone should be sent.  The MGC determines when to
   remove the rsp signal.

   When a continuity test is performed on a Termination, no echo devices
   or codecs shall be active on that Termination.

   Performing voice path assurance as part of continuity testing is
   provisioned by bilateral agreement between network operators.

      (Informative Note) Example tones and test procedure details are
      given in Q.724 sections 7 and 8, Q.764 section 2.1.8 and Q.1902.4.

E.11  Network Package

   PackageID: nt (0x000b)
   Version: 1
   Extends: None

   This package defines properties of network terminations independent
   of network type.

E.11.1   Properties

   Maximum Jitter Buffer
   PropertyID: jit (0x0007)

      This property puts a maximum size on the jitter buffer.

      Type: integer in milliseconds

      Possible values: This property is specified in milliseconds.

      Defined in: LocalControlDescriptor

      Characteristics: read/write

E.11.2   Events

   network failure
   EventID: netfail, 0x0005

      The termination generates this event upon detection of a failure
      due to external or internal network reasons.

      EventDescriptor parameters

         None.

      ObservedEventsDescriptor parameters

         cause
         ParameterID: cs (0x0001)

            Type: string

            Possible values: any text string

            This parameter may be included with the failure event to
            provide diagnostic information on the reason of failure.

   quality alert
   EventID: qualert, 0x0006

      This property allows the MG to indicate a loss of quality of the
      network connection.  The MG may do this by measuring packet loss,
      interarrival jitter, propagation delay and then indicating this
      using a percentage of quality loss.

      EventDescriptor parameters

         Threshold
         ParameterId: th (0x0001)

            Type: integer

            Possible values: 0 to 99

            Description: threshold for percent of quality loss measured,
            calculated based on a provisioned method, that could take
            into consideration packet loss, jitter, and delay for
            example.  Event is triggered when calculation exceeds the
            threshold.

      ObservedEventsDescriptor parameters

         Threshold
         ParameterId: th (0x0001)

            Type: integer

            Possible values: 0 to 99

            Description: percent of quality loss measured, calculated
            based on a provisioned method, that could take into
            consideration packet loss, jitter, and delay for example.

E.11.3   Signals

   None.

E.11.4   Statistics

   Duration
   StatisticsID: dur (0x0001)

      Description: provides duration of time the termination has been in
      the Context.

      Type: double, in milliseconds

   Octets Sent
   StatisticID: os (0x0002)

      Type: double

      Possible values: any 64-bit integer

   Octets Received
   StatisticID: or (0x0003)

      Type: double

      Possible values: any 64-bit integer

E.11.5   Procedures

   None.

E.12  RTP Package

   PackageID: rtp (0x000c)
   Version: 1
   Extends: Network Package version 1

   This package is used to support packet-based multimedia data transfer
   by means of the Real-time Transport Protocol (RTP) [RFC 1889].

E.12.1   Properties

   None.

E.12.2   Events

   Payload Transition
   EventID: pltrans, 0x0001

      This event detects and notifies when there is a transition of the
      RTP payload format from one format to another.

      EventDescriptor parameters

         None.

      ObservedEventsDescriptor parameters

         ParameterName: rtppayload
         ParameterID: rtppltype, 0x01

         Type: list of enumerated types.

         Possible values: The encoding method shall be specified by
         using one or several valid encoding names, as defined in the
         RTP AV Profile or registered with IANA.

E.12.3   Signals

   None.

E.12.4   Statistics

   Packets Sent
   StatisticID: ps (0x0004)

      Type: double

      Possible values: any 64-bit integer

   Packets Received
   StatisticID: pr (0x0005)

      Type: double

      Possible values: any 64-bit integer

   Packet Loss
   StatisticID: pl (0x0006)

      Describes the current rate of packet loss on an RTP stream, as
      defined in IETF RFC 1889.  Packet loss is expressed as percentage
      value: number of packets lost in the interval between two
      reception reports, divided by the number of packets expected
      during that interval.

      Type: double

      Possible values: a 32-bit whole number and a 32-bit fraction.

   Jitter
   StatisticID: jit (0x0007)

      Requests the current value of the interarrival jitter on an RTP
      stream as defined in IETF RFC 1889.  Jitter measures the variation
      in interarrival time for RTP data packets.

   Delay
   StatisticID:delay (0x0008)

      Requests the current value of packet propagation delay expressed
      in timestamp units.  Same as average latency.

E.12.5   Procedures

   None.

   E.13       GEN0202   Added note that TDM package could also apply
                        to other transports.

   E.13.1     IG1100    Changed default for echo cancellation from
                        "on" to provisioned.

   E.13.1     IG0601    Corrected type for gain property.

   Appendix   TTPOST    Included a number of corrections which were
      I                 not picked up in H.248.1 Amendment 1 but which
                        do appear in H.248.1 v2.

Intellectual Property Rights

   The ITU draws attention to the possibility that the practice or
   implementation of this RFC may involve the use of a claimed
   Intellectual Property Right.  The ITU takes no position concerning
   the evidence, validity or applicability of claimed Intellectual
   Property Rights, whether asserted by ITU members or others outside of
   the Recommendation development process.

   As of the date of approval of this RFC, the ITU had received notice
   of intellectual property, protected by patents, which may be required
   to implement this RFC.  However, implementors are cautioned that this
   may not represent the latest information and are therefore strongly
   urged to consult the TSB patent database.

   The IETF has also received notice of intellectual property claims
   relating to Megaco/H.248.1.  Please consult the IETF IPR
   announcements at http://www.ietf.org/ipr.html.

E.13.2   Events

   None.

E.13.3   Signals

   None.

E.13.4   Statistics

   None.

E.13.5   Procedures

   None.

APPENDIX I  EXAMPLE CALL FLOWS (INFORMATIVE)

   All H.248.1 implementors must read the normative part of this RFC
   carefully before implementing from it.  The examples in this appendix
   should not be used as stand-alone explanations of how to create
   protocol messages.

   The examples in this appendix use SDP for encoding of the Local and
   and Remote stream descriptors. SDP is defined in RFC 2327. If there
   is is any discrepancy between the SDP in the examples, and RFC 2327,
   the the RFC should be consulted for correctness. Audio profiles used
   are are those defined in IETF RFC 1890, and others registered with
   IANA.  For example, G.711 A-law is called PCMA in SDP, and is
   assigned profile 0. G.723.1 is called G723 and is profile 4; H.263 is
   called H263 and is profile 34. See also
   http://www.iana.org/assignments/rtp-parameters.

A.1   Residential Gateway to Residential Gateway Call

   This example scenario illustrates the use of the elements of the
   protocol to set up a Residential Gateway to Residential Gateway call
   over an IP-based network.  For simplicity, this example assumes that
   both Residential Gateways involved in the call are controlled by the
   same Media Gateway Controller.

A.1.1 Programming Residential GW Analog Line Terminations for Idle
   Behavior

   The following illustrates the API invocations from the Media Gateway
   Controller and Media Gateways to get the Terminations in this
   scenario programmed for idle behavior.  Both the originating and
   terminating Media Gateways have idle AnalogLine Terminations
   programmed to look for call initiation events (i.e., -offhook) by
   using the Modify Command with the appropriate parameters.  The null
   Context is used to indicate that the Terminations are not yet
   involved in a Context.  The ROOT termination is used to indicate the
   entire MG instead of a termination within the MG.

   In this example, MG1 has the IP address 124.124.124.222, MG2 is
   125.125.125.111, and the MGC is 123.123.123.4. The default Megaco
   port is 55555 for all three.

   1. An MG registers with an MGC using the ServiceChange command:

   MG1 to MGC:

   MEGACO/1 [124.124.124.222] Transaction = 9998 {
       Context = - {

           ServiceChange = ROOT {Services {
               Method=Restart,
               ServiceChangeAddress=55555, Profile=ResGW/1}
           }
       } }

   2. The MGC sends a reply:

   MGC to MG1:

   MEGACO/1 [123.123.123.4]:55555 Reply = 9998 {
      Context = - {ServiceChange = ROOT {
        Services {ServiceChangeAddress=55555, Profile=ResGW/1} } } }

   3. The MGC programs a Termination in the NULL context.  The
   terminationId is A4444, the streamId is 1, the requestId in the
   Events descriptor is 2222.  The mId is the identifier of the sender
   of this message, in this case, it is the IP address and port
   [123.123.123.4]:55555.  Mode for this stream is set to SendReceive.
   "al" is the analog line supervision package.  Local and Remote are
   assumed to be provisioned.

   MGC to MG1:

   MEGACO/1 [123.123.123.4]:55555 Transaction = 9999 {
       Context = - {
           Modify = A4444 {
               Media { Stream = 1 {
                        LocalControl {
                            Mode = SendReceive,
                            tdmc/gain=2,  ; in dB,
                            tdmc/ec=on
                        },

                    }
               },
               Events = 2222 {al/of(strict=state)}
           }
       } }


   The dialplan script could have been loaded into the MG previously.
   Its function would be to wait for the OffHook, turn on dialtone and
   start collecting DTMF digits.  However in this example, we use the
   digit map, which is put into place after the offhook is detected
   (step 5 below).

   Note that the embedded EventsDescriptor could have been used to
   combine steps 3 and 4 with steps 8 and 9, eliminating steps 6 and 7.

   4. The MG1 accepts the Modify with this reply:

   MG1 to MGC:

   MEGACO/1 [124.124.124.222]:55555

   Reply = 9999 {
      Context = - {Modify = A4444} }

   5. A similar exchange happens between MG2 and the MGC, resulting in
   an idle Termination called A5555.

A.1.2 Collecting Originator Digits and Initiating Termination

   The following builds upon the previously shown conditions.  It
   illustrates the transactions from the Media Gateway Controller and
   originating Media Gateway (MG1) to get the originating Termination
   (A4444) through the stages of digit collection required to initiate a
   connection to the terminating Media Gateway (MG2).

   6. MG1 detects an offhook event from User 1 and reports it to the
   Media Gateway Controller via the Notify Command.

   MG1 to MGC:

   MEGACO/1 [124.124.124.222]:55555 Transaction = 10000 {
      Context = - {
          Notify = A4444 {ObservedEvents =2222 {
            19990729T22000000:al/of(init=false)}}
      } }

   7. And the Notify is acknowledged.

   MGC to MG1:

   MEGACO/1 [123.123.123.4]:55555 Reply = 10000 {

       Context = - {Notify = A4444} }

   8. The MGC Modifies the termination to play dial tone, to look for
   digits according to Dialplan0 and to look for the on-hook event now.

   MGC to MG1:

   MEGACO/1 [123.123.123.4]:55555 Transaction = 10001 {
       Context = - {
           Modify = A4444 {
               Events = 2223 {
                   al/on(strict=state), dd/ce {DigitMap=Dialplan0}
               },
               Signals {cg/dt},
               DigitMap= Dialplan0{ (0| 00|[1-
   7]xxx|8xxxxxxx|Fxxxxxxx|Exx|91xxxxxxxxxx|9011x.)}
           }
       } }

   9. And the Modify is acknowledged.

   MG1 to MGC:

   MEGACO/1 [124.124.124.222]:55555 Reply = 10001 {
       Context = - {Modify = A4444} }

   10.   Next, digits are accumulated by MG1 as they are dialed by User
   1.  Dialtone is stopped upon detection of the first digit.  When an
   appropriate match is made of collected digits against the currently
   programmed Dialplan for A4444, another Notify is sent to the Media
   Gateway Controller.

   MG1 to MGC:

   MEGACO/1 [124.124.124.222]:55555 Transaction = 10002 {
      Context = - {
          Notify = A4444 {ObservedEvents =2223 {
            19990729T22010001:dd/ce{ds="916135551212",Meth=UM}}}
      } }

   11.   And the Notify is acknowledged.

   MGC to MG1:

   MEGACO/1 [123.123.123.4]:55555 Reply = 10002 {
       Context = - {Notify = A4444} }


   12.   The controller then analyses the digits and determines that a
   connection needs to be made from MG1 to MG2.  Both the TDM

   termination A4444, and an RTP termination are added to a new context
   in MG1.  Mode is ReceiveOnly since Remote descriptor values are not
   yet specified.  Preferred codecs are in the MGC's preferred order of
   choice.

   MGC to MG1:

   MEGACO/1 [123.123.123.4]:55555 Transaction = 10003 {
       Context = $ {
          Add = A4444,
          Add = $ {
              Media {
                Stream = 1 {
                     LocalControl {
                         Mode = ReceiveOnly,

                         nt/jit=40 ; in ms
                     },
                     Local { v=0 c=IN IP4 $ m=audio $ RTP/AVP 4
   a=ptime:30 v=0 c=IN IP4 $ m=audio $ RTP/AVP 0
                     }
                }
             }
          }
       } }


      NOTE - The MGC states its preferred parameter values as a series
      of SDP blocks in  Local.  The MG fills in the Local Descriptor in
      the Reply.

   13.   MG1 acknowledges the new Termination and fills in the Local IP
   address and UDP port.  It also makes a choice for the codec based on
   the MGC preferences in Local.  MG1 sets the RTP port to 2222.

   MG1 -> MGC:

   MEGACO/1 [124.124.124.222]:55555 Reply = 10003 {
      Context = 2000 {
         Add = A4444,
         Add=A4445{
            Media {
                Stream = 1 {
                    Local { v=0 o=- 2890844526 2890842807 IN IP4
   124.124.124.222 s=- t= 0 0 c=IN IP4 124.124.124.222 m=audio 2222
   RTP/AVP 4 a=ptime:30 a=recvonly
                    } ; RTP profile for G.723.1 is 4
                }

            }
         }
      } }

   14.   The MGC will now associate A5555 with a new Context on MG2, and
   establish an RTP Stream (i.e., A5556 will be assigned), SendReceive
   connection through to the originating user, User 1.  The MGC also
   sets ring on A5555.

   MGC to MG2:

   MEGACO/1 [123.123.123.4]:55555 Transaction = 50003 {
       Context = $ {
          Add = A5555  { Media {
               Stream = 1 {
                    LocalControl {Mode = SendReceive} }},
         Events=1234{al/of(strict=state)},
               Signals {al/ri}

               },
          Add  = $ {Media {
               Stream = 1 {
                    LocalControl {
                       Mode = SendReceive,
                       nt/jit=40 ; in ms
                    },
                    Local { v=0 c=IN IP4 $ m=audio $ RTP/AVP 4
   a=ptime:30
                    },
                    Remote { v=0 c=IN IP4 124.124.124.222 m=audio 2222
   RTP/AVP 4 a=ptime:30
                    } ; RTP profile for G.723.1 is 4
                }
             }
         }
      } }

   15.   This is acknowledged.  The stream port number is different from
   the control port number.  In this case it is 1111 (in the SDP).

   MG2 to MGC:

   MEGACO/1 [125.125.125.111]:55555 Reply = 50003 {
      Context = 5000 {
      Add = A5555,
         Add = A5556{
            Media {
               Stream = 1 {

                   Local { v=0 o=- 7736844526 7736842807 IN IP4
   125.125.125.111 s=- t= 0 0 c=IN IP4 125.125.125.111 m=audio 1111
   RTP/AVP 4 }
               } ; RTP profile for G723.1 is 4
            }
          }

      } }

   16.   The above IPAddr and UDPport need to be given to MG1 now.

   MGC to MG1:

   MEGACO/1 [123.123.123.4]:55555 Transaction = 10005 {
     Context = 2000 {
       Modify = A4444 {
         Signals {cg/rt}
       },
       Modify = A4445 {
          Media {
               Stream = 1 {
                   Remote { v=0 o=- 7736844526 7736842807 IN IP4
   125.125.125.111 s=- t= 0 0 c=IN IP4 125.125.125.111 m=audio 1111
   RTP/AVP 4
                   }
               } ; RTP profile for G723.1 is 4
           }
       }
     } }


   MG1 to MGC:

   MEGACO/1 [124.124.124.222]:55555 Reply = 10005 {
      Context = 2000 {Modify = A4444, Modify = A4445} }

   17.   The two gateways are now connected and User 1 hears the
   RingBack.  The MG2 now waits until User2 picks up the receiver and
   then the two-way call is established.

   From MG2 to MGC:

   MEGACO/1 [125.125.125.111]:55555 Transaction = 50005 {
      Context = 5000 {

          Notify = A5555 {ObservedEvents =1234 {
            19990729T22020002:al/of(init=false)}}
      } }

   From MGC to MG2:

   MEGACO/1 [123.123.123.4]:55555 Reply = 50005 {
       Context = - {Notify = A5555} }

   From MGC to MG2:

   MEGACO/1 [123.123.123.4]:55555 Transaction = 50006 {
      Context = 5000 {
         Modify = A5555 {
            Events = 1235 {al/on(strict=state)},
            Signals { } ; to turn off ringing
         }
      } }

   From MG2 to MGC:

   MEGACO/1 [125.125.125.111]:55555 Reply = 50006 {
    Context = 5000 {Modify = A4445} }

   18.   Change mode on MG1 to SendReceive, and stop the ringback.

   MGC to MG1:

   MEGACO/1 [123.123.123.4]:55555 Transaction = 10006 {
      Context = 2000 {
         Modify = A4445 {
            Media {
               Stream = 1 {
                  LocalControl {
                     Mode=SendReceive

                  }
               }
            }
         },
         Modify = A4444 {
            Signals { }
         }

      } }

   from MG1 to MGC:

   MEGACO/1 [124.124.124.222]:55555 Reply = 10006 {
      Context = 2000 {Modify = A4445, Modify = A4444}}

   19.   The MGC decides to Audit the RTP termination on MG2.

   MGC -> MG2:

   MEGACO/1 [123.123.123.4]:55555 Transaction = 50007 {
      Context = - {AuditValue = A5556{
         Audit{Media, DigitMap, Events, Signals, Packages, Statistics }}
      } }

   20.   The MG2 replies.

   MG2 -> MGC:

   MEGACO/1 [125.125.125.111]:55555 Reply = 50007 {
      Context = - { AuditValue = A5556 {
             Media {
                TerminationState { ServiceStates = InService,
            Buffer = OFF },
          Stream = 1 {
                    LocalControl { Mode = SendReceive,
                       nt/jit=40 },
                    Local { v=0 o=- 7736844526 7736842807 IN IP4
   125.125.125.111 s=- t= 0 0 c=IN IP4 125.125.125.111 m=audio 1111
   RTP/AVP  4 a=ptime:30
                   },
                    Remote { v=0 o=- 2890844526 2890842807 IN IP4
   124.124.124.222 s=- t= 0 0 c=IN IP4 124.124.124.222 m=audio 2222
   RTP/AVP  4 a=ptime:30
                    } } },
              Events,
           Signals,
           DigitMap,
          Packages {nt-1, rtp-1},
             Statistics { rtp/ps=1200,  ; packets sent
                          nt/os=62300, ; octets sent
                          rtp/pr=700, ; packets received
                          nt/or=45100, ; octets received
                          rtp/pl=0.2,  ; % packet loss
                          rtp/jit=20,
                          rtp/delay=40 } ; avg latency
          }

       } }

   21.   When the MGC receives an onhook signal from one of the MGs, it
   brings down the call.  In this example, the user at MG2 hangs up
   first.

   From MG2 to MGC:

   MEGACO/1 [125.125.125.111]:55555 Transaction = 50008 {
      Context = 5000 {
          Notify = A5555 {ObservedEvents =1235 {
             19990729T24020002:al/on(init=false)}
          }
      } }

   From MGC to MG2:

   MEGACO/1 [123.123.123.4]:55555 Reply = 50008 {

       Context = - {Notify = A5555} }

   22.   The MGC now sends both MGs a Subtract to take down the call.
   Only the subtracts to MG2 are shown here.  Each termination has its
   own set of statistics that it gathers.  An MGC may not need to
   request both to be returned.  A5555 is a physical termination, and
   A5556 is an RTP termination.

   From MGC to MG2:

   MEGACO/1 [123.123.123.4]:55555 Transaction = 50009 {
      Context = 5000 {
         Subtract = A5555 {Audit{Statistics}},
         Subtract = A5556 {Audit{Statistics}}
      } }

   From MG2 to MGC:

   MEGACO/1 [125.125.125.111]:55555 Reply = 50009 {
      Context = 5000 {
        Subtract = A5555 {
             Statistics {
                nt/os=45123, ; Octets Sent
                nt/dur=40 ; in seconds
                }
          },
          Subtract = A5556 {
             Statistics {
                rtp/ps=1245, ; packets sent

                nt/os=62345, ; octets sent
                rtp/pr=780, ; packets received
                nt/or=45123, ; octets received
                rtp/pl=10, ;  % packets lost
                rtp/jit=27,
                rtp/delay=48 ; average latency
             }
          }
      } }

   23.   The MGC now sets up both MG1 and MG2 to be ready to detect the
   next off-hook event.  See step 1.  Note that this could be the
   default state of a termination in the null context, and if this were
   the case, no message need be sent from the MGC to the MG.  Once a
   termination returns to the null context, it goes back to the default
   termination values for that termination.

APPENDIX II  Changes From RFC 3015

   In the following table, "source" indicates when the change was first
   approved.  It has the following values:

   IG1100: H.248 Implementor's Guide approved in November, 2000 (as TD
   Plen-39, Christian Groves, editor).

   IG0601: H.248 Implementor's Guide approved in June, 2001 (as  TD
   Plen-15, Christian Groves, editor).

   IGDUB: Draft H.248 Implementor's Guide approved at the Q.3
   Rapporteur's meeting held near Dublin, October 2001 (as TD-28, Terry
   Anderson, editor).

   GEN0202: added at the Geneva meeting, February 2002, which consented
   to H.248 v1 Amendment 1 (as TD Plen-36r1, Marcello Pantaleo, editor).

   ITUPOST: added in post-Geneva editing by the ITU-T.

   TTPOST: added in post-approval editing by the Megaco Chair, Tom
   Taylor, who assembled this document for submission.

   Section    Source                       Change

   1          ITUPOST   Reference changed from H.248 to H.248.1.

   2.1        GEN0202   Added reference to X.690.

   2.1        GEN0202   Added reference to X.690.

   2.1        GEN0202   Added reference to X.690.

   2.2         IGDUB    Added informative references to Q.724, Q.764,
                        and Q.1902.4.

   4          IG0601    Added expansion of ALF.

   5          TTPOST    Gave priority to IETF conventions (added at
                        start of document).

   6.1.1      IG0601    Added text regarding use of wildcards for
                        context identifiers.  (This information
                        already appeared in section 8.1.2.  The IG
                        change subsequently disappeared.)

   6.1.1      IG1100    Added ranking of priority values.

   2.2         IGDUB    Added informative references to Q.724, Q.764,
                        and Q.1902.4.

   4          IG0601    Added expansion of ALF.

   5          TTPOST    Gave priority to IETF conventions (added at
                        start of document).

   6.1.1      IG0601    Added text regarding use of wildcards for
                        context identifiers.  (This information
                        already appeared in section 8.1.2.  The IG
                        change subsequently disappeared.)

   6.1.1      IG1100    Added ranking of priority values.

   6.2        TTPOST    Added asterisks to multiplexing diagrams to
                        indicate centre of context.  Added Figure 6a
                        showing cascading of multiplexes.

   6.2        TTPOST    Added asterisks to multiplexing diagrams to
                        indicate centre of context.  Added Figure 6a
                        showing cascading of multiplexes.

   6.2        TTPOST    Added asterisks to multiplexing diagrams to
                        indicate centre of context.  Added Figure 6a
                        showing cascading of multiplexes.

   6.2.2      IG0601    Added text indicating that ALL does not
                        include ROOT.

   6.2.3      IG1100    Added text indicating what packages a peer can
                        indicate support for, when some of them are
                        extensions of others.

   6.2.3      IG1100    Added text indicating what packages a peer can
                        indicate support for, when some of them are
                        extensions of others.

   6.2.4      IG1100    Added Topology and Error Descriptors to table.

   6.2.4      IG1100    Added Topology and Error Descriptors to table.

   6.2.4      IG1100    Added Topology and Error Descriptors to table.

   6.2.4      IG1100    Added Topology and Error Descriptors to table.

   6.2.4      IG1100    Added Topology and Error Descriptors to table.

   6.2.5       IGDUB    Specified error code to return if ROOT used
                        inappropriately.

   7.1.1      IG1100    Added qualification to explanation of effect
                        of missing Audit Descriptor, excepting
                        Subtract.

   7.1.3      GEN0202   Changed "inputs" to "bearers" to be consistent
                        with terminology in 6.2.

   7.1.4      IG0601    Small change to make clear that more than one
                        of Local, Remote, and LocalControl can be
                        included in the default streamId.

   7.1.7      GEN0202   Added text requiring processing of media in
                        any of the reserved formats, where more than
                        one has been reserved in a given stream.

   7.1.7      GEN0202   Added text requiring processing of media in
                        any of the reserved formats, where more than
                        one has been reserved in a given stream.

   7.1.8       IGDUB    Added restriction to at most one m= line per
                        session description.

   7.1.9      IG1100    Added note to say event remains active after
                        it has been notified, so long as it is still
                        present in the active Events Descriptor.

   7.1.9      IG1100    Added note to say event remains active after
                        it has been notified, so long as it is still
                        present in the active Events Descriptor.

   7.1.9      IG1100    Added note to say event remains active after
                        it has been notified, so long as it is still
                        present in the active Events Descriptor.

   7.1.11     IG1100    Deleted text discussing type of Signals List.

   7.1.11     IG1100    Deleted text discussing type of Signals List.

   7.1.11     IG1100    Deleted text discussing type of Signals List.

   7.1.11     IG1100    Deleted text discussing type of Signals List.

   7.1.11     IG1100    Deleted text discussing type of Signals List.

   7.1.12     GEN0202   Improved wording of introductory paragraph and
                        added text making content of returned
                        Descriptor clear.

   7.1.14.2   GEN0202   Added text indicating that when the start
                        timer is set to 0, initial digit timing is
                        disabled and the MG waits indefinitely for
                        digits.

   7.1.14.2   GEN0202   Added text pointing out that default digit
                        timer values should be provisioned, but can be
                        overridden in the digit map.

   7.1.14.3   GEN0202   Changed result of long-short digit timer
                        conflict from undefined to long.

   7.1.14.6   IG1100    Clarified that the digit map is provided by
                        the eventDM parameter, which must be present.

   7.1.14.7   GEN0202   Added text clarifying that events covered by
                        the digit map completion event have no side-
                        effects unless separately enabled.

   7.1.14.8   IG0601    Added requirement that the event specification
                        include the eventDM parameter.

   7.1.17     GEN0202   Deleted provision that time is expressed in
                        UTC (since intention was to use format, not
                        time zone).

   7.1.17     GEN0202   Deleted provision that time is expressed in
                        UTC (since intention was to use format, not
                        time zone).

   7.1.18     IG1100    Added text clarifying effect of not mentioning
              TTPOST    a termination in a topology Descriptor, and
                        default topology for a new termination.  (This
                        text got lost between the Dublin meeting and
                        the production of H.248 Amendment 1 out of the
                        Geneva 02/02 meeting.  It has been added back
                        to the present document.)

   7.1.18     IG1100    Added text clarifying effect of not mentioning
              TTPOST    a termination in a topology Descriptor, and
                        default topology for a new termination.  (This
                        text got lost between the Dublin meeting and
                        the production of H.248 Amendment 1 out of the
                        Geneva 02/02 meeting.  It has been added back
                        to the present document.)

   7.1.19     IG0601    Added paragraph giving guidance on level at
                        which errors should be reported.

   7.1.19     IG0601    Added paragraph giving guidance on level at
                        which errors should be reported.

   7.2        IG1100    Noted possibility of Error Descriptor in reply
                        to any command.

   7.2.1      IG1100    Removed restriction on use of CHOOSE wildcard.

   7.2.1      IG1100    Removed restriction on use of CHOOSE wildcard.

   7.2.2      GEN0202   Added text on side-effects of Modify of a
                        multiplexing termination.

   7.2.2      GEN0202   Added text on side-effects of Modify of a
                        multiplexing termination.

   7.2.3       IGDUB    Added text clarifying effect of empty
                        AuditDescriptor in Subtract.

   7.2.3       IGDUB    Added text clarifying effect of empty
                        AuditDescriptor in Subtract.

   7.2.3       IGDUB    Added text clarifying effect of empty
                        AuditDescriptor in Subtract.

   7.2.4      GEN0202   Added text on side-effects of Move of a
                        multiplexing termination.

   7.2.4      GEN0202   Added text on side-effects of Move of a
                        multiplexing termination.

   7.2.4      GEN0202   Added text on side-effects of Move of a
                        multiplexing termination.

   7.2.4      GEN0202   Added text on side-effects of Move of a
                        multiplexing termination.

   7.2.5      IG1100    Added table entry (ALL, specific) to determine
                        context in which termination currently
                        resides.

   7.2.5      IG1100    Added table entry (ALL, specific) to determine
                        context in which termination currently
                        resides.

   7.2.5      IG1100    Added table entry (ALL, specific) to determine
                        context in which termination currently
                        resides.

   7.2.6      GEN0202   Added table similar to that in 7.2.5.

   7.2.7      IG1100    Noted possibility of sending Error Descriptor
                        in Notify.

   7.2.7      IG1100    Noted possibility of sending Error Descriptor
                        in Notify.

   7.2.7      IG1100    Noted possibility of sending Error Descriptor
                        in Notify.

   7.2.8       IGDUB    Corrected "gateway" to "MGC" in discussion of
                        returned ServiceChangeMgcId parameter.

   7.2.8       IGDUB    Corrected "gateway" to "MGC" in discussion of
                        returned ServiceChangeMgcId parameter.

   7.2.8       IGDUB    Corrected "gateway" to "MGC" in discussion of
                        returned ServiceChangeMgcId parameter.

   7.2.8       IGDUB    Corrected "gateway" to "MGC" in discussion of
                        returned ServiceChangeMgcId parameter.

   7.2.8       IGDUB    Corrected "gateway" to "MGC" in discussion of
                        returned ServiceChangeMgcId parameter.

   7.2.8       IGDUB    Corrected "gateway" to "MGC" in discussion of
                        returned ServiceChangeMgcId parameter.

   7.3        IG0601    Removed error code documentation to Annex L
              ITUPOST   (now H.248.8).

   8          IG1100    Added requirement that an Action be non-empty.

   8          GEN0202   Added context properties and context property
                        audit requests to commands as potential
                        contents of actions.

   8.1.2      GEN0202   Added prohibition on using partial contextIDs
                        with ALL wildcards.

   8.2.2      IG0601    Corrected Actions to Commands when discussing
                        partially-understood action.

   8.2.2      IG0601    Corrected Actions to Commands when discussing
                        partially-understood action.

   8.2.2      IG0601    Corrected Actions to Commands when discussing
                        partially-understood action.

   8.2.2      IG0601    Corrected Actions to Commands when discussing
                        partially-understood action.

   8.3        IG0601    Added text expanding on independence of
                        transactions from messages.

   9          ITUPOST   Indicated that additional transports may be
                        defined in separate Recommendations as well as
                        annexes to the primary specification.

   9          IG0601    Gave specific example of "request source
                        address" for IP.

   8.3        IG0601    Added text expanding on independence of
                        transactions from messages.

   9          ITUPOST   Indicated that additional transports may be
                        defined in separate Recommendations as well as
                        annexes to the primary specification.

   9          IG0601    Gave specific example of "request source
                        address" for IP.

   9.1        IG0601    Restored restriction, but noted that it
                        applied only to transport not guaranteeing
                        ordered delivery.

   9.1        IG0601    Restored restriction, but noted that it
                        applied only to transport not guaranteeing
                        ordered delivery.

   10.2       IG1100    Corrected length of synthesized address field
                        from 10 to 20 hex digits and indicated that
                        calculation should be over entire message, not
                        just one transaction.

   11.2       IG1100    Corrected "Transaction Accept" to "Transaction
                        Reply".

   11.2       IG1100    Corrected "Transaction Accept" to "Transaction
                        Reply".

   11.4       IG0601    Noted that support of redundant MGs requires
              GEN0202   use of a reliable transport and support in the
                        MGC.  Added more explanation in Geneva.

   11.5       GEN0202   Changed text on replies to transactions in
                        progress during handoff.  Replies now
                        discarded when the service relationship with
                        the old MGC has ended, rather than sent to the
                        new MGC.  The new MGC could still send replies
                        to requests sent to the old MGC.

   11.5       GEN0202   Changed text on replies to transactions in
                        progress during handoff.  Replies now
                        discarded when the service relationship with
                        the old MGC has ended, rather than sent to the
                        new MGC.  The new MGC could still send replies
                        to requests sent to the old MGC.

   11.5       GEN0202   Changed text on replies to transactions in
                        progress during handoff.  Replies now
                        discarded when the service relationship with
                        the old MGC has ended, rather than sent to the
                        new MGC.  The new MGC could still send replies
                        to requests sent to the old MGC.

   11.5       GEN0202   Changed text on replies to transactions in
                        progress during handoff.  Replies now
                        discarded when the service relationship with
                        the old MGC has ended, rather than sent to the
                        new MGC.  The new MGC could still send replies
                        to requests sent to the old MGC.

   12.1.1     IG1100    Made prohibition on overloading of identifiers
                        in extended packages transitive through all
                        ancestors of the extended package.

   12.1.1     IG1100    Made prohibition on overloading of identifiers
                        in extended packages transitive through all
                        ancestors of the extended package.

   12.1.2     GEN0202   Provided requirements for content of the
                        "Possible Values" template item, including
                        specification of default values or behaviour.

   12.1.2     GEN0202   Provided requirements for content of the
                        "Possible Values" template item, including
                        specification of default values or behaviour.

   12.1.2     GEN0202   Provided requirements for content of the
                        "Possible Values" template item, including
                        specification of default values or behaviour.

   12.1.4     GEN0202   Added requirement to specify the default
                        signal type, and specify a default duration
                        for TO signals.  Also noted that duration is
                        meaningless for BR, and that the signal type
                        might be dependent on the values of other
                        signal parameters.

   12.2       GEN0202   Fixed section title (covers only event and
                        signal parameters, not properties or
                        statistics).

   12.2       IG1100    Reserved SPA and EPA prefixes, so they are not
                        to be used for signal and event parameter
                        tokens.

   12.2       IG0601    Expanded list of reserved prefixes.

   12.2        IGDUB    Clarified the set of types allowed for signal
                        and event parameters.

   12.2       GEN0202   Added requirement to specify the base type of
                        a sub-list.

   12.2       GEN0202   Provided requirements for content of the
                        "Possible Values" template item, including
                        specification of default values or behaviour.

   12.4        IGDUB    Corrected to indicate identifiers must start
                        with alphabetic rather than alphanumeric
                        character.

   13.1       IG0601    Changed private range of binary package
                        identifiers to convenient hex values.

   A          GEN0202   Removed versions from X.680 and X.690
                        references.

   A.2         IGDUB    Added note warning that the syntax alone does
                        not provide a complete description of the
                        constraints, but must be supplemented by a
                        reading of the text and comments.

   A.2        IG0601    Added description of double wrapping of
                        parameters declared as OCTET STRING.

   A.2        GEN0202   Some editing of double wrapping description to
                        use ASN.1, BER in their proper places.  Added
                        possibility of encoding strings as UTF8String,
                        but only if they contain non-ASCII characters.

   A.2         IGDUB    Added line in table on double wrapping of true
                        octet strings.

   A.2        IG1100    Corrected and expanded comments describing
                        mtpAddress form of MId.  Fixed maximum length
                        of mtpAddress both here and in
                        ServiceChangeAddress.

   A.2        IG0601   Inserted missing lines in IP4Address
                        production.

   A.2        IG0601    Modified TransactionResponseAck to allow
                        acknowledgement of multiple ranges of
                        transactionIds.

   A.2        IG0601    Corrected numerical value of CHOOSE as a
                        context identifier.

   A.2         IGDUB    Added missing extension marker in
                        TopologyRequest.

   A.2        IG1100    AuditReply and AuditResult modified to bring
                        binary functionality into line with text
                        functionality.

   A.2        IG0601    Removed OPTIONAL tag from terminationID in
                        NotifyReply.

   A.2        IG0601    Added extraInfo substructure to EventParameter
                        and SigParameter.

   A.2        IG0601    Modified MediaDescriptor to make it optional
                        to specify a stream.

   A.2        IG0601    Added OPTIONAL tags to reserveValue and
                        reserveGroup.

   A.2         IGDUB    Added to comments for pkgdName to indicate
                        applicability to event names, signal names,
                        and statisticIds as well as property.

   A.2        IG0601    RequestID made optional in EventsDescriptor
                        and SecondEventsDescriptor and comment added
                        saying it must be present if events are
                        present.

   A.2        IG1100    Added OPTIONAL tags on RequestActions and
                        SecondRequestedActions keepActive BOOLEANs.

   A.2        IG1100    Added comment to indicate requestID value to
                        use in an AuditCapReply.

   A.2        GEN0202   Added comment to DigitMapValue indicating time
                        units for timers.

   A.2        IG0601    Added comment indicating coding of Value for
              GEN0202   ServiceChangeReason.  Cleaned up in Geneva to
                        use ASN.1 and BER in their proper places.

   A.2        IG0601    Inserted missing extension marker in
                        ServiceChangeParm production.

   A.2        IG0601    Aligned definition of mtpAddress in
                        ServiceChangeAddress with that in MId.

   A.2        IG0601    Added timestamp to ServiceChangeResParm.

   A.2         IGDUB    Changed type of profileName in
                        ServiceChangeProfile to IA5String.

   A.2        IG0601    Made returned value optional in
                        statisticsParameter, to support
                        auditCapability result.

   A.2        GEN0202   Added reference to ISO 8601:1988 for
                        TimeNotation.

   A.2        IG1100    Value production modified to support the
                        sublist parameter type.

   A.3        IG1100    Corrected ABNF for digitStringlisT, replacing
                        "/" with "|".

   A.3        IG1100    Added parentheses to digitMapRange production.

   A.3        IG1100    Replaced more abbreviated syntax for pathName
                        with fuller definition and constraints copied
                        from B.2.

   B.2         IGDUB    Added note warning that the syntax alone does
                        not provide a complete description of the
                        constraints, but must be supplemented by a
                        reading of the text and comments.

   B.2        IG0601    Added note warning that the interpretation of
                        symbols is context-dependent.

   B.2        IG1100    Added comment to indicate case insensitivity
                        of protocol (excepting SDP) and ABNF.

   B.2        IG0601    Expanded upon and capitalized this comment.

   B.2        IG0601    Lengthy note added on the coding of the VALUE
                        construct.

   B.2         IGDUB    Deleted sentence in note suggesting that
                        packages could add new types for properties,
                        parameters, or statistics.

   B.2        IG0601    Added note indicating that parsers should
                        allow for white space preceding the first line
                        of SDP in Local or Remote.

   B.2         IGDUB    Added comments identifying the O- and W- tags.

   B.2        IG1100    Moved wildcard tag up from individual commands
                        to commandRequestList.

   B.2        GEN0202   Added additional error case to actionReply.

   B.2        IG0601    Modified syntax of auditOther to allow return
                        of terminationID only.

   B.2         IGDUB    Corrected upper limit for V4hex.

   B.2        IG1100    Corrected and expanded comments describing
                        mtpAddress form of MId.

   B.2        IG0601    Modified comment to mediaParm to make
                        streamParms and StreamDescriptor mutually
                        exclusive.

   B.2        GEN0202   Modified comment further to indicate at most
                        one instance of terminationStateDescriptor.

   B.2        GEN0202   Expanded comment for streamParm to indicate
                        the restriction on repetition is per item.

   B.2        IG0601    Modified "at most once" comments to localParm,
                        terminationStateParm, and modemType, to allow
                        multiple instances of propertyParm in the
                        first two cases and extensionParameter in the
                        last one.

   B.2        IG0601    Added note before description of Local and
                        Remote, pointing out that the octet value x00
                        is not allowed in octetString.

   B.2        IG0601    Syntax for eventsDescriptor, embedFirst, and
                        eventBufferDescriptor modified to make
                        contents beyond token optional.

   B.2         IGDUB    Replaced "event" by "item" in comment to
                        pkgdName because pkgdName applies to
                        properties, signals, and statistics as well.

   B.2        IG0601    Corrected placement of EQUAL in eventDM
                        production.

   B.2        IG1100    Added comment and syntax to indicate requestID
                        value to use in an AuditCapReply.

   B.2        IG1100    Corrected Modem Descriptor to allow package
                        items as properties.

   B.2        IG0601    Comment to modemType changed to allow multiple
                        instances of extensionParameter.

   B.2        GEN0202   Comment added to indicate units for Timer.

   B.2        IG1100    Added parentheses to digitMapRange production.

   B.2        IG1100    Added comment to serviceChangeParm,
                        restricting each parameter to one appearance.

   B.2        IG0601    Added comments making serviceChangeMgcId and
                        serviceChangeAddress mutually exclusive in
                        ServiceChangeParm and servChgReplyParm.

   B.2         IGDUB    Added comment to serviceChangeParm indicating
                        that ServiceChangeMethod and
                        ServiceChangeReason are required.

   B.2        IG0601    Added Timestamp to servChgReplyParm.

   B.2        IG0601    Added comment indicating coding of Value for
                        ServiceChangeReason.

   B.2        IG0601    Modified ServiceChangeAddress to use MId
                        definition for full address.

   B.2        IG1100    Made returned value optional in
                        statisticsParameter, to support
                        auditCapability result.

   B.2        IG1100    Changed topologyDescriptor to allow multiple
                        triples.

   B.2        IG0601    Added comment forbidding use of a double quote
                        within a quotedString value.

   B.2        IG1100    Reserved prefixes for new tokens added to
                        signalParameter and eventParameter, to avoid
                        collision with package names.

   B.2        IG1100    EmbedToken and EmergencyToken changed to
                        remove clash with EventBufferToken.

   B.3        IG1100    New section describing hexadecimal octet
                        encoding.

   B.4        IG1100    New section describing hex octet sequence.

   C          IG1100    Added permission to use Annex C properties in
                        LocalControl as well as in Local and Remote.

   C          IG0601    Added text making support of all properties of
                        Annex C optional.

   C           IGDUB    Added directions to reconcile tabulated
                        formats with allowed types for properties.

   C.1        IG1100    Corrected Q.765 reference to Q.765.5 for
                        ACodec.

   C.1        IG1100    Deprecated Echocanc codepoint in favour of
                        package-defined property.

   C.4        ITUPOST   Updated references from Q.2961 to Q.2961.1.

   C.4         IGDUB    Added details on format of VPVC.

   C.9        IG1100    Renamed USI to layer1prot.

   C.9        IG1100    Deprecated ECHOCI codepoint in favour of
                        package-defined property.

   C.9        IG1100    Added new USI property.

   C.11       IG1100    Added m= line tag.

   D.1        IG0601    Added explanation of ALF.

   D.1.5       IGDUB    Expanded text indicating that when trying to
                        reestablish contact with the previously
                        controlling MGC the MG uses the Disconnected
                        method.

   E.1.2      GEN0202   Added missing EventsDescriptor parameters
                        lines.

   E.1.2      GEN0202   For the Signal Completion event:
                        - corrected the description of how it is
                        enabled
                        - heavily edited the description of the Signal
                        Identity observed event parameter and added a
                        type.

   E.1.2       IGDUB    The timeout completion reason for the Signal
                        Completion event was broadened to include
                        other circumstances where the signal completed
                        on its own.

   E.1.2      IG1100    Added signal list ID observed event parameter
                        to the Signal Completion event.

   E.2.1      IG0601    Added missing read only, read-write
                        specifications.

   E.2.1      IG0601    Split ProvisionalResponseTimer properties into
                        one for MG, one for MGC.

   E.3        GEN0202   Added "Designed to be extended only" to
                        tonegen package description.

   E.4        GEN0202   Added "Designed to be extended only" to
                        tonedet package description.

   E.4.2      GEN0202   Added type for tone ID observed parameter for
                        Long Tone Detected event.

   E.6.2      IG1100    Corrected binary identifier for digit map
                        completion event to avoid clash with base
                        package.

   E.6.2      IG1100    Removed procedural text.

   E.6.5      IG1100    Added procedural text indicating where to find
                        the applicable digit map and indicating the
                        error to return if the parameter is missing.

   E.6.5      IG0601    Further modified procedural text.

   E.7.3      IG1100    Corrected text identifier for payphone
                        recognition tone to avoid clash with base
                        package.

   E.10.5      IGDUB    Provided informative references for tones and
                        procedures for continuity check.

   E.13       GEN0202   Added note that TDM package could also apply
                        to other transports.

   E.13.1     IG1100    Changed default for echo cancellation from
                        "on" to provisioned.

   E.13.1     IG0601    Corrected type for gain property.

   Appendix   TTPOST    Included a number of corrections which were
      I                 not picked up in H.248.1 Amendment 1 but which
                        do appear in H.248.1 v2.

Intellectual Property Rights

   The ITU draws attention to the possibility that the practice or
   implementation of this RFC may involve the use of a claimed
   Intellectual Property Right.  The ITU takes no position concerning
   the evidence, validity or applicability of claimed Intellectual
   Property Rights, whether asserted by ITU members or others outside of
   the Recommendation development process.

   As of the date of approval of this RFC, the ITU had received notice
   of intellectual property, protected by patents, which may be required
   to implement this RFC.  However, implementors are cautioned that this
   may not represent the latest information and are therefore strongly
   urged to consult the TSB patent database.

   The IETF has also received notice of intellectual property claims
   relating to Megaco/H.248.1.  Please consult the IETF IPR
   announcements at http://www.ietf.org/ipr.html.

Acknowledgments

   Megaco/H.248.1 is the result of hard work by many people in both the
   IETF and in ITU-T Study Group 16.  This section records those who
   played a prominent role in ITU-T meetings, on the Megaco list, or
   both.

   Megaco/H.248 owes a large initial debt to the MGCP protocol (RFC
   2705), and thus to its authors, Mauricio Arango, Andrew Dugan, Ike
   Elliott, Christian Huitema, and Scott Pickett.  Flemming Andreasen
   does not appear on this list of authors, but was a major contributor
   to the development of both MGCP and Megaco/H.248.1.  RFC 3435 has an
   extensive acknowledgement of many other people who worked on media
   gateway control before Megaco got started.

   The authors of the first Megaco RFCs (2805, then 3015) were Fernando
   Cuervo, Nancy Greene, Abdallah Rayhan, Christian Huitema, Brian
   Rosen, and John Segers.  Christian Groves conceived and was editor of
   Annex C.  The people most active on the Megaco list in the period
   leading up to the completion of RFC 2885 were Brian Rosen, Tom
   Taylor, Nancy Greene, Christian Huitema, Matt Holdrege, Chip Sharp,
   John Segers, Michael Thomas, Henry Sinnreich, and Paul Sijben.  The
   people who sacrificed sleep and meals to complete the massive amount
   of work required in the decisive Study Group 16 meeting of February,
   2000, were Michael Brown, Ranga Dendi, Larry Forni, Glen Freundlich,
   Christian Groves, Alf Heidemark, Steve Magnell, Selvam Rengasami,
   Rich Rubin, Klaus Sambor, John Segers, Chip Sharp, Tom Taylor, and
   Stephen Terrill.

   The most active people on the Megaco list in the period since the
   February 2000 have been Tom Taylor, Brian Rosen, Christian Groves,
   Madhu Babu Brahmanapally, Troy Cauble, Terry Anderson, Chuong Nguyen,
   and Kevin Boyle, but many other people have been regular
   contributors.  Brian Rosen did tremendous service in putting together
   the Megaco interoperability tests.  On the Study Group 16 side, the
   editorial team for the final revised document in February, 2002
   included Christian Groves, Marcello Pantaleo, Terry Anderson, Peter
   Leis, Kevin Boyle, and Tom Taylor.

   Tom Taylor as Megaco Chair managed the day to day operation of the
   Megaco list, with Brian Rosen taking an equal share of the burden for
   most of the last three years.  Glen Freundlich as the Study Group 16
   Rapporteur ran the ITU-T meetings and ensured that all of the work at
   hand was completed.  Without Glen's determination the Megaco/H.248

   standard would have taken at least half a year longer to produce.
   Christian Groves filled in ably as Rapporteur when Glen could no
   longer take part.

Authors' Addresses

   Terry L. Anderson
   24 Hill St
   Bernardsville, NJ 07924
   USA

   EMail: tlatla@verizon.net


   Christian Groves
   Ericsson AsiaPacificLab Australia
   37/360 Elizabeth St
   Melbourne, Victoria 3000
   Australia

   EMail: Christian.Groves@ericsson.com.au


   Marcello Pantaleo
   Ericsson Eurolab Deuschland
   Ericsson Allee 1
   52134 Herzogenrath, Germany

   EMail: Marcello.Pantaleo@eed.ericsson.se


   Tom Taylor
   Nortel Networks
   1852 Lorraine Ave,
   Ottawa, Ontario
   Canada K1H 6Z8

   Phone: +1 613 736 0961
   EMail: taylor@nortelnetworks.com

Full Copyright Statement

   Copyright (C) The Internet Society (2003).  All Rights Reserved.

   This document and translations of it may be copied and furnished to
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   or assist in its implementation may be prepared, copied, published
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Acknowledgement

   Funding for the RFC Editor function is currently provided by the
   Internet Society.


        
        
EID 256 (Verified) is as follows:

Section: None

Original Text:

None

Corrected Text:

None
Notes:
Errata can be found in the ITU-T Implementor's Guide at:
http://www.itu.int/itudoc/itu-t/com16/implgd/h248.1v1.html