1、INTERNATIONAL TELECOMMUNICATION UNION ITUmT TELECOM M U N I CATI ON STANDARDIZATION SECTOR OF ITU Q.1912.3 (07200 1 ) SERIES Q: SWITCHING AND SIGNALLING Specifications of signalling related to Bearer Independent Call Control (BICC) Interworking between H.323 and the Bearer Independent Call Control p
2、rotocol ITU-T Recommendation Q.1912.3 (Formerly CCITT Recommendation) ITU-T Q-SERIES RECOMMENDATIONS SWITCHING AND SIGNALLING SIGNALLING IN THE INTERNATIONAL MANUAL SERVICE FUNCTIONS AND INFORMATION FLOWS FOR SERVICES IN THE ISDN SPECIFICATIONS OF SIGNALLING SYSTEMS No. 4 AND No. 5 SPECIFICATIONS OF
3、 SIGNALLING SYSTEM No. 6 SPECIFICATIONS OF SIGNALLING SYSTEM R1 SPECIFICATIONS OF SIGNALLING SYSTEM R2 DIGITAL EXCHANGES INTERWORKING OF SIGNALLING SYSTEMS SPECIFICATIONS OF SIGNALLING SYSTEM No. 7 43 INTERFACE DIGITAL SUBSCRIBER SIGNALLING SYSTEM No. 1 PUBLIC LAND MOBILE NETWORK DVTERWORKING WITH S
4、ATELLITE MOBILE SYSTEMS INTELLIGENT NETWORK INTERNATIONAL AUTOMATIC AND SEMI-AUTOMATIC WORKING CLAUSES APPLICABLE TO ITU-T STANDARD SYSTEMS SIGNALLING REQUIREMENTS AND PROTOCOLS FOR IMT-2000 Q. 1-4.3 Q.4-Q.59 Q .60-Q. 99 Q.io-Q.119 4.120-4.249 4.250-4.309 4.3 104.399 4.4004.499 Q.500-Q.599 Q.600-Q.6
5、99 Q.700-Q.799 4.800-4.849 Q.lOOO-Q.1099 Q.1200-Q.1699 Q.1700-Q. 1799 Q .8 5 O-Q .999 Q.1100-Q.1199 SPECIFICATIONS OF SIGNALLING RELATED TO BEARER INDEPENDENT CALL Q.1900-Q.1999 CONTROL (BICC) BROADBAND ISDN 4.2000-4.2999 For further details, please refer to the list of ITU-T Recommendations. ITU-T
6、Recommendation Q.1912.3 Interworking between H.323 and the Bearer Independent Call Control protocol Summary This Recommendation defines the signalling intenvorking between the Bearer Independent Call Control (BICC) protocol and H.323. It defines in particular the signalling intenvorking between the
7、BICC protocol and the H.225.0 Multimedia Call Control protocol based on the intenvorking between H.225.0 and the ISDN User Part (ISUP) protocol of Signalling System No. 7. Source ITU-T Recommendation Q. 1912.3 was prepared by ITU-T Study Group 11 (2001 -2004) and approved under the WTSA Resolution 1
8、 procedure on 2 July 200 1. ITU-T Q.1912.3 (07/2001) 1 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
9、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
10、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 fali within ITU-Ts purview, the necessary standards are prepared on a collaborative basis w
11、ith IS0 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
12、 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
13、of approval of this Recommendation, ITU had not 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 t
14、he TSB patent database. O ITU 2002 AI1 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. 11 ITU-T 4.1912.3 (07/2001) CONTENTS Page 1 Scope . 2
15、 References . 3 Definitions 4 Abbreviations 5 General considerations 6 Intenvorking considerations . 6.1 General 6.2 Prevention of speech clipping . 6.3 Codec negotiation and out-of-band transport of DTMF and tone information 6.4 Interworking of ISDN supplementary services Appendix I . Guidelines BI
16、CUH.323 interworking for end-to-end codec negotiation I . 1 Introduction . 1.2 H.323 to BICC interworking 1.2.1 If the H.245 procedures are used (with a separate H.245 control channel or using the H.245 encapsulation method) 1.2.2 If Fast Connect procedure is used BICC to H.323 interworking 1.3.1 If
17、 H.245 procedures are used (with a separate H.245 control channel or using the H.245 encapsulation method) 1.3.2 If Fast Connect procedure is used 1.3 ITU-T Q.1912.3 (07/2001) 1 2 3 3 7 7 . 111 ITU-T Recommendation Q.1912.3 Interworking between H.323 and the Bearer Independent Call Control protocol
18、1 Scope This Recommendation defines the signalling interworking between the Bearer Independent Call Control (BICC) protocol and H.323. It defines in particular the signalling interworking between the BICC protocol and the H.225.0 Multimedia Call Control protocol in an H.323 network based on the inte
19、rworking between H.225.0 and the ISDN User Part (ISUP) protocol of Signalling System No. 7. The interworking between H.245 and BICC is for further study (some aspects are addressed in 6.3 and Appendix I). BICC is the protocol defined in ITU-T Recommendations Q. 1902.1 to Q. 1902.4 5. The Multimedia
20、Call Control protocol is defined in ITU-T H.225.0 i for a network in accordance with ITU-T H.323 3. ISUP is the protocol defined in ITU-T Recommendations 4.761 to 4.764 4. The description of the signalling interworking between the H.225 .O Multimedia Call Control protocol and the BICC protocol in th
21、is Recommendation builds upon: - The signalling interworking between the H.225 .O Multimedia Call Control protocol and the ISDN User Part (ISUP) protocol of Signalling System No. 7 as defined in Annex CH.246 2. The signalling interworking between the Bearer Independent Call Control (BICC) protocol a
22、nd the ISDN User Part (ISUP) protocol of Signalling System No. 7 as defined in ITU-T 4.1912.1 6. The scope of this Recommendation with regard to the signalling interworking between the H.225.0 Multimedia Call Control protocol and the BICC protocol is as shown in Figure 1. - ITU-T Q.1912.3 (07/2001)
23、1 H.323 network Scope of this Scope of ITU-T 4.1912.1 Recommendation I BICC network using separate call and bearer signalling H.225.0 H.245 - I I / / i N-ISUP i i control i . , . . $*e: CSF-N . , - BICC +-, i call/bearer i i BICC 4I _I_ P BIWF Figure UQ.1912.3 - Scope of this Recommendation for BICC
24、H.225.0 interworking 2 References The following ITU-T Recommendations and other references contain provisions which, through reference in this text, constitute provisions of this Recommendation. At the time of publication, the editions indicated were valid. All Recommendations and other references a
25、re subject to revision; users of this Recommendation 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. ITU-T H.225 .O (2000)
26、, Call signalling protocols and media stream packetization for packet- based multimedia communication systems. ITU-T H.246 Annex C (2000), ISDN user part function - H.225. O Interworking. ITU-T H.323 (2000), Packet-based multimedia communications systems. ITU-T 4.761 to 4.764 (1999), SpeciJications
27、of Signalling System No. 7- ISDN userpart ITU-T Q. 1902.1 to Q. 1902.4 (200 i), Specifications of the Bearer Independent Call Control protocol (BICC). ITU-T Q. 1 9 12.1 (200 i), Interworking between Signalling System No. 7 ISDN user part (ISUP) and the Bearer Independent Call Control protocol. ITU-T
28、 H.450.x-family (1 998 onwards), Procedures and the signalling protocols between Y 323 entities for the control of supplementary services. ITU-T Implementors Guide (2001) for H.323, H.225.0, H.245, H.246, H.283, H.235, H.450-series and H.341 Recommendations. ITU-T H.245 (200 i), Control protocol for
29、 multimedia communication. (ISUP). ITU-T Q.1912.3 (0712001) 3 Definitions For BICC specific terminology, the reader is referred to ITU-T Q.1902.1 5. Q. 1912.1 BICC 4 Abbreviations This Recommendation uses the following abbreviations: APM Application Transport Message BCF-N Bearer Control Nodal Funct
30、ion BICC Bearer Independent Call Control BIWF Bearer Interworking Function CSF-N Call Service Nodal Function DTMF Dual Tone Multi Frequency ISDN Integrated Services Digital Network I SN Interface Serving Node ISUP ISDN User Part SCN Switched Circuit Network e 5 General considerations This clause des
31、cribes the intenvorking principle between H.225.0 and BICC based on the intenvorking between H.225 .O and ISUP concatenated with the interworking between ISUP and BICC. This refers to the necessary mapping of signalling information to achieve connectivity and functionality between an H.323 network a
32、nd a BICC network. Figure 2 provides the functional grouping of the interworking functions involved following the half call model description technique for BICC. Half call Half call 4 b4 b I T1 1 1 1194041 Figure 2/Q.1912.3 - Functional description of the interworking configuration ITU-T 4.1912.3 (0
33、7/2001) 3 6 Interworking considerations 6.1 General The interworking between H.225.0 and BICC shall act according to the interworking between H.225.0 and ISUP in Annex UH.246 3, and the additional interworking statements in the Implementors Guide for H.323, H.225.0, H.245, H.246, H.283, H.235, H.450
34、-series and H.341 Recommendations in ITU-T Implementors Guide SI, concatenated with the interworking between ISUP and BICC in ITU-T 4.1912.1 6. 6.2 Prevention of speech clipping For an incoming H.323 call for which the incoming bearer is not established yet in the H.323 network, the Continuity Indic
35、ator in the Nature of Connection Indicators parameter in the IAM in BICC shall be set to indicate “COT to be expected“ if the ISN is aware that the call establishment procedures in ITU-T H.245 9 can take place in the H.323 network without waiting until an ACM message is received in BICC (Note). The
36、Continuity message, with the Continuity Indicators parameter set to “Continuity“ shall be sent in BICC upon successful completion of the incoming H.323 bearer set-up procedures. NOTE - In some H.323 implementations, the H.245 call establishment procedures cannot be initiated before an ACM is receive
37、d from the BICC network (because the H.245 procedures are not handled until a CONNECT is received or because a CALL PROCEEDING message is not generated before an ACM is received). In such cases, speech clipping cannot be prevented. H.323 networks using such implementations should not be interconnect
38、ed to BICC networks. The H.245 call establishment procedures shall be initiated as soon as possible on the H.323 side. If the Fast Connect procedure is used on the H.323 side, the ISN shall first check that the bearer establishment can be successfully completed according to the proposals received in
39、 the fastStart element of the SETUP message received from the H.323 side, before sending the IAM in BICC. 6.3 Interworking procedures related to codec negotiation (including mid-call codec modification and mid-call codec negotiation procedures) and out-of-band transport of DTMF and tone information
40、have also to be considered in case of interworking between an H.323 network and a BICC network. These procedures require the definition of interactions between the BICC protocol and some parts of the H.245 protocol. The accurate definition of these procedures is for further study. Appendix 1 provide
41、s guidelines for the implementation of the end-to-end codec negotiation procedures through a BICC and H.323 network. Codec negotiation and out-of-band transport of DTMF and tone information 6.4 Please note that the interworking of ISDN supplementary services (ITU-T H.450.x-series 7) is for further s
42、tudy. Interworking of ISDN supplementary services 4 ITU-T Q.1912.3 (07/2001) APPENDIX I Guidelines BICCm.323 interworking for end-to-end codec negotiation 1.1 Introduction The H.245 capability exchange procedures are more complex than the BICC codec negotiation procedures since H.323 nodes have the
43、possibility to separately indicate receive and transmit capabilities, as well as various combination of modes in which the node can operate simultaneously. A different codec can be selected for each unidirectional media channel in H.323. As the same codec is used for transmission and reception in a
44、BICC network, only the codecs which are proposed by the H.323 network for reception and transmission will be included in the initial BICC Supported Codecs list used to perform the BICC codec negotiation. This principle is generally applied in the procedures defined below although it is not explicitl
45、y mentioned. 1.2 1.2.1 1) 2) H.323 to BICC interworking BICC network Node A ISN B Node C If the H.245 procedures are used (with a separate H.245 control channel or using the H.245 encapsulation method) If the capabilities supported by the preceding H.323 node (node A) are received by the ISN (in an
46、H.245 TerminalCapabilitySet message) before the IAM is sent on the outgoing side, the Supported Codec List sent in the IAM is derived from the capability structures contained in the received TerminalCapabilitySet message by deleting the codecs that cannot be used for the call (not offered by the ISN
47、) and adding (with a lower priority) the codecs that can be used for the call (proposed by the ISN) but were not indicated in the received capabilities from the preceding H.323 node (node A). The ISN shall wait until an APM with the selected codec is received before indicating its capabilities to th
48、e preceding H.323 node (node A). - If the Selected Codec received in the APM was contained in the received TerminalCapabilitySet message from the preceding H.323 node (node A), the H.245 TerminalCapabilitySet message sent by the ISN shall only contain the selected codec received in the BICC APM. The
49、 end-to-end codec negotiation procedures are successfully completed. The codec selected by the ISN on the H.323 side (sent in the OpenLogicalChannel message) is the codec resulting from the BICC negotiation procedure. If the Selected Codec received in the APM does not belong to the capabilities indicating by the preceding H.323 node (node A), a transcoder shall be used. If the capabilities supported by the preceding H.323 node (node A) are not received by the ISN (in an H.245 TerminalCapabilitySet message) before the IAM is sent on the outgoing s
