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`INTERNATIONAL TELECOMMUNICATION UNION
`
`
`
`
`
`ITU-T
`
`TELECOMMUNICATION
`STANDARDIZATION SECTOR
`OF ITU
`
`H.323
`
`(11/2000)
`
`SERIES H: AUDIOVISUAL AND MULTIMEDIA SYSTEMS
`Infrastructure of audiovisual services – Systems and
`terminal equipment for audiovisual services
`
`Packet-based multimedia communications
`systems
`
`ITU-T Recommendation H.323
`(Formerly CCITT Recommendation)
`
`Zoho Corp. and Zoho Corp. Pvt., Ltd.
`Exhibit 1033 – 001
`
`

`

`
`ITU-T H-SERIES RECOMMENDATIONS
`AUDIOVISUAL AND MULTIMEDIA SYSTEMS
`
`
`CHARACTERISTICS OF VISUAL TELEPHONE SYSTEMS
`INFRASTRUCTURE OF AUDIOVISUAL SERVICES
`General
`Transmission multiplexing and synchronization
`Systems aspects
`Communication procedures
`Coding of moving video
`Related systems aspects
`SYSTEMS AND TERMINAL EQUIPMENT FOR AUDIOVISUAL SERVICES
`SUPPLEMENTARY SERVICES FOR MULTIMEDIA
`
`For further details, please refer to the list of ITU-T Recommendations.
`
`
`H.100–H.199
`
`H.200–H.219
`H.220–H.229
`H.230–H.239
`H.240–H.259
`H.260–H.279
`H.280–H.299
`H.300–H.399
`H.450–H.499
`
`
`Zoho Corp. and Zoho Corp. Pvt., Ltd.
`Exhibit 1033 – 002
`
`

`

`ITU-T Recommendation H.323
`
`
`
`
`Packet-based multimedia communications systems
`
`
`
`
`Summary
`that provide multimedia
`terminals and other entities
`This Recommendation describes
`communications services over Packet Based Networks (PBN) which may not provide a guaranteed
`Quality of Service. H.323 entities may provide real-time audio, video and/or data communications.
`Support for audio is mandatory, while data and video are optional, but if supported, the ability to use
`a specified common mode of operation is required, so that all terminals supporting that media type
`can interwork.
`The packet based network over which H.323 entities communicate may be a point-to-point
`connection, a single network segment, or an internetwork having multiple segments with complex
`topologies.
`H.323 entities may be used in point-to-point, multipoint, or broadcast (as described in ITU-T
`Rec. H.332) configurations. They may interwork with H.310 terminals on B-ISDN, H.320 terminals
`on N-ISDN, H.321 terminals on B-ISDN, H.322 terminals on Guaranteed Quality of Service LANs,
`H.324 terminals on GSTN and wireless networks, V.70 terminals on GSTN, and voice terminals on
`GSTN or ISDN through the use of Gateways.
`H.323 entities may be integrated into personal computers or implemented in stand-alone devices
`such as videotelephones.
`Note that the title of H.323 (1996) was "Visual telephone systems and equipment for local area
`networks which provide a non-guaranteed quality of service". The title changed in Version 2 to be
`consistent with its expanded scope.
`Products claiming compliance with Version 1 of H.323 shall comply with all of the mandatory
`requirements of H.323 (1996) which references ITU-T Rec. H.225.0 (1996) and H.245 (1997).
`Version 1 products shall be identified by H.225.0 messages containing a protocolIdentifier = {itu-t
`(0) recommendation (0) h (8) 2250 version (0) 1} and H.245 messages containing a
`protocolIdentifier = {itu-t (0) recommendation (0) h (8) 245 version (0) 2}.
`Products claiming compliance with Version 2 of H.323 shall comply with all of the mandatory
`requirements of this Recommendation, H.323 (1998), which references ITU-T Rec. H.225.0 (1998)
`and H.245 (1998 or later). Version 2 products shall be identified by H.225.0 messages containing a
`protocolIdentifier = {itu-t (0) recommendation (0) h (8) 2250 version (0) 2} and H.245 messages
`containing a protocolIdentifier = {itu-t (0) recommendation (0) h (8) 245 version (0) x}, where "x"
`is 3 or higher.
`Products claiming compliance with Version 3 of H.323 shall comply with all of the mandatory
`requirements of this Recommendation, H.323 (1999), which references ITU-T Rec. H.225.0 (1999)
`and H.245 (1999 or later). Version 3 products shall be identified by H.225.0 messages containing a
`protocolIdentifier = {itu-t (0) recommendation (0) h (8) 2250 version (0) 3} and H.245 messages
`containing a protocolIdentifier = {itu-t (0) recommendation (0) h (8) 245 version (0) x}, where "x"
`is 5 or higher.
`
`
`
`
`
`ITU-T Rec. H.323 (11/2000)
`
`i
`
`Zoho Corp. and Zoho Corp. Pvt., Ltd.
`Exhibit 1033 – 003
`
`

`

`
`
`Products claiming compliance with Version 4 of H.323 shall comply with all of the mandatory
`requirements of this Recommendation, H.323 (2000), which references ITU-T Rec. H.225.0 (2000)
`and H.245 (2000 or later). Version 4 products shall be identified by H.225.0 messages containing a
`protocolIdentifier = {itu-t (0) recommendation (0) h (8) 2250 version (0) 4} and H.245 messages
`containing a protocolIdentifier = {itu-t (0) recommendation (0) h (8) 245 version (0) x}, where "x"
`is 7 or higher.
`
`Source
`ITU-T Recommendation H.323 was prepared by ITU-T Study Group 16 (2001-2004) and approved
`under the WTSA Resolution 1 procedure on 17 November 2000, and on 1 March 2001 for Annex L.
`
`
`ii
`
`ITU-T Rec. H.323 (11/2000)
`
`Zoho Corp. and Zoho Corp. Pvt., Ltd.
`Exhibit 1033 – 004
`
`

`

`
`
`FOREWORD
`The International Telecommunication Union (ITU) is the United Nations specialized agency in the field of
`telecommunications. The ITU Telecommunication Standardization Sector (ITU-T) is a permanent organ of
`ITU. ITU-T is responsible for studying technical, operating and tariff questions and issuing Recommendations
`on them with a view to standardizing telecommunications on a worldwide basis.
`The World Telecommunication Standardization Assembly (WTSA), which meets every four years,
`establishes the topics for study by the ITU-T study groups which, in turn, produce Recommendations on these
`topics.
`The approval of ITU-T Recommendations is covered by the procedure laid down in WTSA Resolution 1.
`In some areas of information technology which fall within ITU-T's purview, the necessary standards are
`prepared on a collaborative basis with ISO and IEC.
`
`
`
`
`
`
`NOTE
`In this Recommendation, the expression "Administration" is used for conciseness to indicate both a
`telecommunication administration and a recognized operating agency.
`
`
`
`
`INTELLECTUAL PROPERTY RIGHTS
`ITU draws attention to the possibility that the practice or implementation of this Recommendation may
`involve the use of a claimed Intellectual Property Right. 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 Recommendation, ITU had received notice of intellectual property,
`protected by patents, which may be required to implement this Recommendation. However, implementors are
`cautioned that this may not represent the latest information and are therefore strongly urged to consult the
`TSB patent database.
`
`
`
`
`
` ITU 2002
`All rights reserved. No part of this publication may be reproduced or utilized in any form or by any means,
`electronic or mechanical, including photocopying and microfilm, without permission in writing from ITU.
`
`
`
`
`
`ITU-T Rec. H.323 (11/2000)
`
`iii
`
`Zoho Corp. and Zoho Corp. Pvt., Ltd.
`Exhibit 1033 – 005
`
`

`

`
`1
`
`2
`
`3
`
`4
`
`5
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`6
`6.1
`6.2
`
`6.3
`
`6.4
`6.5
`6.6
`6.7
`6.8
`
`
`
`CONTENTS
`
`Scope...........................................................................................................................
`
`Normative references..................................................................................................
`
`Definitions ..................................................................................................................
`
`Symbols and abbreviations .........................................................................................
`
`Conventions ................................................................................................................
`
`System description......................................................................................................
`Information streams ....................................................................................................
`Terminal characteristics..............................................................................................
`6.2.1 Terminal elements outside the scope of this Recommendation ....................
`6.2.2 Terminal elements within the scope of this Recommendation......................
`6.2.3 Packet based network interface .....................................................................
`6.2.4 Video codec ...................................................................................................
`6.2.5 Audio codec...................................................................................................
`6.2.6 Receive path delay.........................................................................................
`6.2.7 Data channel ..................................................................................................
`6.2.8 H.245 control function...................................................................................
`6.2.9 RAS signalling function ................................................................................
`6.2.10 Call signalling function .................................................................................
`6.2.11 H.225.0 layer .................................................................................................
`Gateway characteristics ..............................................................................................
`6.3.1 Gateway decomposition ................................................................................
`6.3.2 Gateway applications.....................................................................................
`Gatekeeper characteristics ..........................................................................................
`Multipoint controller characteristics...........................................................................
`Multipoint processor characteristics ...........................................................................
`Multipoint control unit characteristics........................................................................
`Multipoint capability...................................................................................................
`6.8.1 Centralized multipoint capability ..................................................................
`6.8.2 Decentralized multipoint capability...............................................................
`6.8.3 Hybrid multipoint – Centralized audio..........................................................
`6.8.4 Hybrid multipoint – Centralized video..........................................................
`6.8.5 Establishment of common mode ...................................................................
`6.8.6 Multipoint rate matching ...............................................................................
`6.8.7 Multipoint lip synchronization ......................................................................
`6.8.8 Multipoint encryption....................................................................................
`6.8.9 Cascading multipoint control units................................................................
`
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`iv
`
`ITU-T Rec. H.323 (11/2000)
`
`Zoho Corp. and Zoho Corp. Pvt., Ltd.
`Exhibit 1033 – 006
`
`

`

`
`6.9
`
`7
`7.1
`
`7.2
`
`7.3
`
`7.4
`7.5
`7.6
`7.7
`7.8
`
`7.9
`
`
`
`Models for supplementary services ............................................................................
`
`Call signalling.............................................................................................................
`Addresses ....................................................................................................................
`7.1.1 Network address ............................................................................................
`7.1.2 TSAP identifier..............................................................................................
`7.1.3 Alias address..................................................................................................
`7.1.4 H.323 URL scheme .......................................................................................
`Registration, Admission and Status (RAS) channel ...................................................
`7.2.1 Gatekeeper discovery ....................................................................................
`7.2.2 Endpoint registration .....................................................................................
`7.2.3 Endpoint location...........................................................................................
`7.2.4 Admissions, bandwidth change, status and disengage ..................................
`7.2.5 Access tokens ................................................................................................
`7.2.6 Alternate gatekeeper procedures ...................................................................
`7.2.7 Usage information reporting..........................................................................
`7.2.8 Call credit-related capabilities.......................................................................
`7.2.9 Alternate transport addresses.........................................................................
`Call signalling channel................................................................................................
`7.3.1 Call signalling channel routing......................................................................
`7.3.2 Control channel routing.................................................................................
`7.3.3 Call signalling and control protocol revisions...............................................
`Call reference value ....................................................................................................
`Call ID.........................................................................................................................
`Conference ID and conference goal............................................................................
`Endpoint call capacity.................................................................................................
`Caller identification services ......................................................................................
`7.8.1 Description of services ..................................................................................
`7.8.2 Messages and information elements..............................................................
`7.8.3 Actions at the originating endpoint ...............................................................
`7.8.4 Actions at the terminating endpoint...............................................................
`7.8.5 Actions at a gatekeeper..................................................................................
`Generic extensible framework ....................................................................................
`7.9.1 Format of a GenericData structure ................................................................
`7.9.2 Negotiation using the extensible framework-general....................................
`7.9.3 Negotiation using the extensible framework-RAS........................................
`7.9.4 Negotiation using the extensible framework – call signalling ......................
`
`8
`
`Call signalling procedures ..........................................................................................
`
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`ITU-T Rec. H.323 (11/2000)
`
`v
`
`Zoho Corp. and Zoho Corp. Pvt., Ltd.
`Exhibit 1033 – 007
`
`

`

`
`8.1
`
`8.2
`
`8.3
`
`8.4
`
`8.5
`
`
`
`Phase A – Call setup ...................................................................................................
`8.1.1 Basic call setup – neither endpoint registered ...............................................
`8.1.2 Both endpoints registered to the same gatekeeper.........................................
`8.1.3 Only calling endpoint has gatekeeper............................................................
`8.1.4 Only called endpoint has gatekeeper .............................................................
`8.1.5 Both endpoints registered to different gatekeepers .......................................
`8.1.6 Optional called endpoint signalling...............................................................
`8.1.7 Fast connect procedure ..................................................................................
`8.1.8 Call setup via gateways .................................................................................
`8.1.9 Call setup with an MCU ................................................................................
`8.1.10 Call forwarding..............................................................................................
`8.1.11 Broadcast call setup.......................................................................................
`8.1.12 Overlapped sending .......................................................................................
`8.1.13 Call setup to conference alias ........................................................................
`8.1.14 Gatekeeper modification of destination addresses ........................................
`8.1.15 Indicating desired protocols...........................................................................
`8.1.16 Gatekeeper requested tones and announcements...........................................
`Phase B – Initial communication and capability exchange ........................................
`8.2.1 Encapsulation of H.245 messages within Q.931 messages...........................
`8.2.2 Tunnelling through intermediate signalling entities......................................
`8.2.3 Switching to a separate H.245 connection.....................................................
`8.2.4
`Initiating H.245 tunnelling in parallel with fast connect ...............................
`Phase C – Establishment of audiovisual communication ...........................................
`8.3.1 Mode changes ................................................................................................
`8.3.2 Exchange of video by mutual agreement ......................................................
`8.3.3 Media stream address distribution.................................................................
`8.3.4 Correlation of media streams in multipoint conferences...............................
`8.3.5 Communication mode command procedures ................................................
`Phase D – Call services...............................................................................................
`8.4.1 Bandwidth changes........................................................................................
`8.4.2 Status .............................................................................................................
`8.4.3 Ad hoc conference expansion........................................................................
`8.4.4 Supplementary services .................................................................................
`8.4.5 Multipoint cascading .....................................................................................
`8.4.6 Third party initiated pause and re-routing .....................................................
`Phase E – Call termination..........................................................................................
`8.5.1 Call clearing without a gatekeeper ................................................................
`8.5.2 Call clearing with a gatekeeper .....................................................................
`8.5.3 Call clearing by gatekeeper ...........................................................................
`
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`vi
`
`ITU-T Rec. H.323 (11/2000)
`
`Zoho Corp. and Zoho Corp. Pvt., Ltd.
`Exhibit 1033 – 008
`
`

`

`
`
`
`8.6
`9
`9.1
`9.2
`9.3
`9.4
`
`9.5
`9.6
`
`9.7
`9.8
`9.9
`
`Protocol failure handling ............................................................................................
`Interoperation with other terminal types.....................................................................
`Speech-only terminals.................................................................................................
`Visual telephone terminals over the ISDN (ITU-T Rec. H.320) ................................
`Visual telephone terminals over GSTN (ITU-T Rec. H.324).....................................
`Visual telephone terminals over mobile radio (ITU-T Rec. H.324/M −
`Annex C/H.324)..........................................................................................................
`Visual telephone terminals over ATM (H.321 and H.310 RAST) .............................
`Visual telephone terminals over guaranteed quality of service LANs
`(ITU-T Rec. H.322) ....................................................................................................
`Simultaneous voice and data terminals over GSTN (ITU-T Rec. V.70)....................
`T.120 terminals on the packet based network.............................................................
`Gateway for H.323 media transport over ATM..........................................................
`
`Optional enhancements...............................................................................................
`10
`Encryption...................................................................................................................
`10.1
`10.2 Multipoint operation ...................................................................................................
`10.2.1 H.243 control and indication .........................................................................
`10.3 Call Linkage in H.323.................................................................................................
`10.3.1 Description.....................................................................................................
`10.3.2 Invocation and operation ...............................................................................
`10.3.3 Interaction with H.450 supplementary services ............................................
`Tunnelling of non-H.323 signalling messages ...........................................................
`10.4.1 Indicating support of tunnelled protocols......................................................
`10.4.2 Requesting a specific protocol tunnel to a gatekeeper ..................................
`10.4.3 Tunnelling a signalling protocol in H.225.0 call signalling messages ..........
`10.4.4 Gatekeeper considerations.............................................................................
`10.5 Use of RTP payload for DTMF digits, telephony tones and telephony signals .........
`
`10.4
`
`Maintenance................................................................................................................
`11
`Loopbacks for maintenance purposes.........................................................................
`11.1
`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.......................................................................................................
`
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`ITU-T Rec. H.323 (11/2000)
`
`vii
`
`Zoho Corp. and Zoho Corp. Pvt., Ltd.
`Exhibit 1033 – 009
`
`

`

`
`
`
`B.5
`
`B.6
`
`B.7
`
`Use of RTP sessions and codec layers........................................................................
`B.5.1 Associate base to audio for lip synchronization ............................................
`B.5.2 Enhancement layer dependency ....................................................................
`Possible layering models ............................................................................................
`B.6.1 Multiple logical channels and RTP sessions for a layered stream ................
`B.6.2
`Impact of one layer per logical channel and per RTP session.......................
`Impact on multipoint conferences...............................................................................
`B.7.1 MC Impartial model ......................................................................................
`B.7.2 MC Decision model.......................................................................................
`B.7.3 Multipoint conference containing endpoints on different bandwidths..........
`Use of network QOS for layered video streams .........................................................
`B.8
`Annex C − H.323 on ATM ......................................................................................................
`C.1
`Introduction.................................................................................................................
`C.2
`Scope...........................................................................................................................
`C.2.1 Point-to-point conferencing...........................................................................
`C.2.2 MCU-based multipoint..................................................................................
`C.2.3 H.323 interoperability with endpoints using IP.............................................
`Architecture ................................................................................................................
`C.3.1 Overview of system.......................................................................................
`C.3.2
`Interoperation with other ITU-T H-series Recommendations endpoints ......
`C.3.3 H.225.0 on IP over ATM...............................................................................
`C.3.4 H.245 on TCP/IP over ATM .........................................................................
`C.3.5 Addressing for A/V streams ..........................................................................
`C.3.6 Transport Capabilities added to TransportCapability Set..............................
`C.3.7 Elements of ATM signalling .........................................................................
`C.3.8 A/V streams on RTP on AAL5......................................................................
`C.3.9 QOS considerations (Optional) .....................................................................
`Protocol section...........................................................................................................
`C.4.1 ATM signalling information elements ..........................................................
`C.4.2 H.245 usage ...................................................................................................
`C.4.3 RTP usage......................................................................................................
`C.4.4
`Interoperation with H.323 on IP ....................................................................
`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.3.1 Opening the voice channel ............................................................................
`D.3.2 Opening the facsimile channels.....................................................................
`
`C.3
`
`C.4
`
`viii
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`
`Zoho Corp. and Zoho Corp. Pvt., Ltd.
`Exhibit 1033 – 010
`
`

`

`
`
`
`
`E.2
`
`D.3.3 DTMF transmission.......................................................................................
`Non-Fast Connect procedures.....................................................................................
`D.4
`Replacing an existing audio stream with a T.38 fax stream .......................................
`D.5
`Usage of the MaxBitRate in messages .......................................................................
`D.6
`Interactions with gateways and T.38/Annex B devices..............................................
`D.7
`Annex E − Framework and wire-protocol for multiplexed call signalling transport...............
`E.1
`Scope...........................................................................................................................
`E.1.1
`Introduction ...................................................................................................
`E.1.2 Signalling models ..........................................................................................
`E.1.3 Optional payload fields..................................................................................
`E.1.4 Wire-protocol.................................................................................................
`H.225.0 call signalling over Annex E.........................................................................
`E.2.1 Rationale........................................................................................................
`E.2.2 H.323 Call-Setup using this annex ................................................................
`E.2.3 Specifics.........................................................................................................
`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.7.1 RAS Signalling (H.225.0 RAS).....................................................................
`F.7.2 Call signalling (H.225.0 Call Control) ..........................................................
`F.7.3 Multimedia system control signalling (H.245)..............................................
`F.7.4 Media Exchange ............................................................................................
`F.7.5 Supplementary services (H.450.x).................................................................
`F.7.6 Third-party initiated pause and re-routing.....................................................
`