1 Scope
2 References
3 Definitions
4 Symbols and abbreviations
5 Conventions
6 System description
6.1 Information streams
6.2 Terminal characteristics
6.3 Gateway characteristics
6.4 Gatekeeper characteristics
6.5 Multipoint controller characteristics
6.6 Multipoint processor characteristics
6.7 Multipoint control unit characteristics
6.8 Multipoint capability
6.9 Models for supplementary services
7 Call signalling
7.1 Addresses
7.2 Registration, Admission and Status (RAS) channel
7.3 Call signalling channel
7.4 Call reference value
7.5 Call ID
7.6 Conference ID and conference goal
7.7 Endpoint call capacity
7.8 Caller identification services
7.9 Generic extensible framework
8 Call signalling procedures
8.1 Phase A – Call setup
8.2 Phase B – Initial communication and capability exchange
8.3 Phase C – Establishment of audiovisual communication
8.4 Phase D – Call services
8.5 Phase E – Call termination
8.6 Protocol failure handling
9 Interoperation with other terminal types
9.1 Speech-only terminals
9.2 Visual telephone terminals over the ISDN (Rec.
ITU-T H.320)
9.3 Visual telephone terminals over GSTN (Rec. ITU-T H.324)
9.4 Visual telephone terminals over mobile radio (Annex C/H.324,
a.k.a. "H.324/M")
9.5 Visual telephone terminals over ATM (H.321 and H.310 RAST)
9.6 Visual telephone terminals over guaranteed quality of service
LANs (Rec. ITU‑T H.322)
9.7 Simultaneous voice and data terminals over GSTN (Rec.
ITU-T V.70)
9.8 T.120 terminals on the packet-based network
9.9 Gateway for H.323 media transport over ATM
10 Optional enhancements
10.1 Encryption
10.2 Multipoint operation
10.3 Call Linkage in H.323
10.4 Tunnelling of non-H.323 signalling messages
10.5 Use of RTP payload for DTMF digits, telephony tones and
telephony signals
11 Maintenance
11.1 Loopbacks for maintenance purposes
11.2 Monitoring methods
Annex A – H.245 messages used by H.323 endpoints
Annex B – Procedures for layered video codecs
B.1 Scope
B.2 Introduction
B.3 Scalability methods
B.4 Call establishment
B.5 Use of RTP sessions and codec layers
B.6 Possible layering models
B.7 Impact on multipoint conferences
B.8 Use of network QoS for layered video streams
Annex C – H.323 on ATM
C.1 Introduction
C.2 Scope
C.3 Architecture
C.4 Protocol section
Annex D – Real-time facsimile over H.323 systems
D.1 Introduction
D.2 Scope
D.3 Procedures for opening channels to send T.38 packets
D.4 Non-fast connect procedures
D.5 Replacing an existing audio stream with a T.38 fax stream
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D.6 Usage of the maxBitRate/bandWidth in messages
D.7 Interactions with gateways and T.38/Annex B devices
Annex E – Framework and wire‑protocol for multiplexed call signalling
transport
E.1 Scope
E.2 H.225.0 call signalling over UDP
Annex F – Simple endpoint types
F.1 Introduction
F.2 Specification conventions
F.3 Scope
F.4 Normative references
F.5 Abbreviations
F.6 Simple (Audio) Endpoint Type – System functionality overview
F.7 Procedures for Simple Endpoint Types
F.8 Security extensions
F.9 Interoperability considerations
F.10 Implementation notes (Informative)
Annex G – Text conversation and Text SET
G.1 Introduction
G.2 Scope
G.3 References
G.4 Definitions
G.5 Capability Advertisement for Text in H.323
G.6 Procedures for opening channels for T.140 text conversation
G.7 Framing and buffering of T.140 data
G.8 Interaction with text conversation facilities in other devices
G.9 Multipoint considerations
G.10 Text SET: Text Conversation Simple Endpoint Type
Annex J – Security for Annex F
J.1 Introduction
J.2 Specification conventions
J.3 Scope
J.4 Abbreviations
J.5 Normative references
J.6 Secure Audio Simple Endpoint Type (SASET)
Annex K – HTTP‑based service control transport channel
K.1 Introduction
K.2 Service control in H.323
K.3 Usage of HTTP
K.4 Example scenarios
K.5 References
Annex L – Stimulus control protocol
L.1 Scope
L.2 Introduction
L.3 Stimulus framework
L.4 References
Annex M1 – Tunnelling of signalling protocols (QSIG) in H.323
M1.1 Scope
M1.2 Normative references
M1.3 Endpoint procedures
M1.4 Tunnelling of QSIG connection-oriented call-independent
signalling
M1.5 Gatekeeper procedures
Annex M2 – Tunnelling of signalling protocols (ISUP) in H.323
M2.1 Scope
M2.2 Normative references
M2.3 Endpoint procedures
M2.4 Gatekeeper procedures
Annex M3 – Tunnelling of DSS1 through H.323
M3.1 Scope
M3.2 Normative references
M3.3 Endpoint procedures
M3.4 Tunnelling of bearer-independent DSS1 signalling
M3.5 Gatekeeper procedures
Annex M4 – Tunnelling of narrow‑band signalling syntax (NSS) for
H.323
M4.1 Scope
M4.2 References
M4.3 H.225.0 Endpoint procedures
M4.4 Gatekeeper procedures
M4.5 RAS procedures for direct-routed calls
Annex M5 – Tunnelling of common alerting protocol (CAP) messages in H.323
M5.1 Scope
M5.2 Normative references
M5.3 Identifying CAP messages
M5.4 Signalling support for CAP
M5.5 Transporting CAP within H.225.0 messages
M5.6 Transmitting and processing CAP messages
M5.7 Requesting CAP support when initiating calls
M5.8 Gatekeeper procedures
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Annex O – Usage of URLs and DNS
O.1 Scope
O.2 Normative references
O.3 Informative references
O.4 H.323 URL
O.5 Encoding of H.323 URL in H.323 messages
O.6 Non-H.323 URLs and URIs within the context of H.323
O.7 H.323 URL parameters
O.8 Usage of the H.323 URL
O.9 Resolving an H.323 URL to IP Address using DNS
O.10 Using DNS SRV Resource Records
Annex P – Transfer of modem signals over H.323
P.1 Scope
P.2 References
P.3 Definitions
P.4 Abbreviations
P.5 Introduction
P.6 Capability advertisement
P.7 Call establishment
P.8 Logical channel signalling
Annex Q – Far-end camera control and H.281/H.224
Q.1 Scope
Q.2 References
Q.3 Introduction
Q.4 Far-end camera control protocol
Q.5 RTP header information
Annex R – Robustness methods for H.323 entities
R.1 Introduction and scope
R.2 Normative references
R.3 Definitions
R.4 Abbreviations
R.5 Overview of the two methods
R.6 Common mechanisms
R.7 Method A: State recovery from neighbours
R.8 Method B: State recovery from a shared repository
R.9 Interworking between robustness methods
R.10 Procedures for recovery
R.11 GenericData usage
Appendix I – Sample MC to terminal communication mode command
I.1 Sample conference Scenario A
I.2 CommunicationModeTable sent to all endpoints
I.3 Sample conference Scenario B
I.4 CommunicationModeTable sent to all endpoints
Appendix II – Transport level resource reservation procedures
II.1 Introduction
II.2 QoS support for H.323
II.3 RSVP background
II.4 The H.245 capability exchange phase
II.5 Open logical channel and setting up reservations
II.6 Close logical channel and tearing down reservations
II.7 Resource reservation for multicast H.323 logical channels
II.8 Synchronized RSVP
Appendix III – Gatekeeper‑based user location
III.1 Introduction
III.2 Signalling
Appendix IV – Signalling prioritized alternative logical channels in ITU-T
H.245
IV.1 Introduction
IV.2 Signalling
Appendix V – Use of ITU-T E.164 and ISO/IEC 11571 numbering plans
V.1 E.164 numbering plan
V.2 Private network number
V.3 H.323 versions 1, 2 and 3 usage
Appendix VI – Description of a typical ITU-T H.323 system over IP
Appendix VII – Informative notes on robustness methods for ITU-T H.323
entities
VII.1 Informative Note 1: Background on robustness methods
VII.2 Informative Note 2: Call state sharing between an entity and
its backup peer