1、 INTERNATIONAL TELECOMMUNICATION UNION ITU-T H.460.13TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU (03/2004) SERIES H: AUDIOVISUAL AND MULTIMEDIA SYSTEMSInfrastructure of audiovisual services Supplementary services for multimedia Called user release control within H.323 systems ITU-T Recommendatio
2、n H.460.13 ITU-T H-SERIES RECOMMENDATIONS AUDIOVISUAL AND MULTIMEDIA SYSTEMS CHARACTERISTICS OF VISUAL TELEPHONE SYSTEMS H.100H.199 INFRASTRUCTURE OF AUDIOVISUAL SERVICES General H.200H.219 Transmission multiplexing and synchronization H.220H.229 Systems aspects H.230H.239 Communication procedures H
3、.240H.259 Coding of moving video H.260H.279 Related systems aspects H.280H.299 Systems and terminal equipment for audiovisual services H.300H.349 Directory services architecture for audiovisual and multimedia services H.350H.359 Quality of service architecture for audiovisual and multimedia services
4、 H.360H.369 Supplementary services for multimedia H.450H.499 MOBILITY AND COLLABORATION PROCEDURES Overview of Mobility and Collaboration, definitions, protocols and procedures H.500H.509 Mobility for H-Series multimedia systems and services H.510H.519 Mobile multimedia collaboration applications an
5、d services H.520H.529 Security for mobile multimedia systems and services H.530H.539 Security for mobile multimedia collaboration applications and services H.540H.549 Mobility interworking procedures H.550H.559 Mobile multimedia collaboration inter-working procedures H.560H.569 BROADBAND AND TRIPLE-
6、PLAY MULTIMEDIA SERVICES Broadband multimedia services over VDSL H.610H.619 For further details, please refer to the list of ITU-T Recommendations. ITU-T Rec. H.460.13 (03/2004) i ITU-T Recommendation H.460.13 Called user release control within H.323 systems Summary This Recommendation specifies a m
7、echanism that allows called H.323 Endpoints to signal that only the called user may release the call and that the release of the call by the calling user must be blocked. This is used for emergency call services where the release of calls to an emergency service operator must be under the control of
8、 the service operator. In addition, a calling H.323 Endpoint may signal that it is able to support called user release control capability. Source ITU-T Recommendation H.460.13 was approved on 15 March 2004 by ITU-T Study Group 16 (2001-2004) under the ITU-T Recommendation A.8 procedure. ii ITU-T Rec
9、. H.460.13 (03/2004) 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
10、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 Rec
11、ommendations 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-Ts purview, the necessary standards are prepared on a collaborative basis with ISO and IEC. NOTE In this Recom
12、mendation, the expression “Administration“ is used for conciseness to indicate both a telecommunication administration and a recognized operating agency. Compliance with this Recommendation is voluntary. However, the Recommendation may contain certain mandatory provisions (to ensure e.g. interoperab
13、ility or applicability) and compliance with the Recommendation is achieved when all of these mandatory provisions are met. The words “shall“ or some other obligatory language such as “must“ and the negative equivalents are used to express requirements. The use of such words does not suggest that com
14、pliance with the Recommendation is required of any party. 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, validi
15、ty 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 not received notice of intellectual property, protected by patents, which may be requir
16、ed 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 2004 All rights reserved. No part of this publication may be reproduced, by any means whatsoever, witho
17、ut the prior written permission of ITU. ITU-T Rec. H.460.13 (03/2004) iii CONTENTS Page 1 Scope 1 2 References. 1 3 Abbreviations 1 4 Called user release control service description. 1 5 Called user release control procedures . 2 5.1 Availability indication 2 5.2 Called user release control invocati
18、on 3 5.3 Called user release control release . 3 5.4 Call termination under called user release control . 4 6 Called user release control indications . 4 6.1 Called user release control parameter. 5 ITU-T Rec. H.460.13 (03/2004) 1 ITU-T Recommendation H.460.13 Called user release control within H.32
19、3 systems 1 Scope Called user release control capability allows a called H.323 Endpoint to control whether the calling H.323 Endpoint is able to initiate release of a connection. In addition, the calling H.323 Endpoint is able to indicate that it can support called user release control capability. C
20、alled user release control is invoked during call establishment and may be subsequently released during the active phase of the call. This capability is sometimes called connection hold. Called user release control capability will allow calls to an emergency service operator to be under the control
21、of the service operator such that the release of the call from the calling H.323 Endpoint is blocked. 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 publicati
22、on, the editions indicated were valid. All Recommendations and other references are 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 cu
23、rrently valid ITU-T Recommendations is regularly published. The reference to a document within this Recommendation does not give it, as a stand-alone document, the status of a Recommendation. ITU-T Recommendation H.225.0 (2003), Call signalling protocols and media stream packetization for packet-bas
24、ed multimedia communication systems. ITU-T Recommendation H.323 (2003), Packet-based multimedia communications systems. 3 Abbreviations This Recommendation uses the following abbreviations: ACF Admission Confirmation ARJ Admission Reject ARQ Admission Request CURC Called User Release Control DRQ Dis
25、engage Request LCF Location Confirmation LRJ Location Reject LRQ Location Request RAS Registration, Admission and Status 4 Called user release control service description Called user release control provides the ability for called H.323 Endpoints to signal that only the called user may release the c
26、all and that the release of the call by the calling user must be blocked at the calling H.323 Endpoint. The calling H.323 Endpoint shall be able to indicate to the called H.323 Endpoint that it can support called user release control capability. 2 ITU-T Rec. H.460.13 (03/2004) Called user release co
27、ntrol is invoked during call establishment when the called H.323 Endpoint signals a called user release control request in the backward direction. The called H.323 Endpoint may also release called user release control once the call has been established such that the calling H.323 Endpoint is then ab
28、le to release the connection. Called user release control shall only be invoked from a called endpoint that is used as an emergency service operator. In addition, while the calling H.323 Endpoint is in the called user release control state, it shall be able to signal to the called H.323 Endpoint whe
29、ther the calling user has attempted to disconnect (go on-hook) and then, subsequently, to re-connect (go off-hook). The called H.323 Endpoint shall also be able to send an alerting request to the calling H.323 Endpoint while in the called user release control state to deliver a ringing indication to
30、 the calling user. 5 Called user release control procedures The called user release control procedures to be performed by H.323 Endpoints and intermediate nodes are described below. 5.1 Availability indication The availability and invocation procedures are illustrated in Figure 1. A calling H.323 En
31、dpoint shall indicate that it is able to support called user release control capability by including a called user release control availability indication (curcAvailable) in the call establishment (Setup) messages. A calling H.323 Endpoint shall indicate that it is not able to support called user re
32、lease control capability by including a called user release control availability indication (curcNotAvailable) in the call establishment (Setup) messages. Intermediate signalling entities shall relay any received called user release control availability indication. The called H.323 Endpoint shall pr
33、oceed as follows: 1) If the call request message contains a curcAvailable indication, it may invoke called user release control procedures. 2) If the call request message contains a curcNotAvailable indication, it may not invoke called user release control procedures. 3) If the call request message
34、does not contain any called user release control availability indication, it may not invoke called user release control procedures. Figure 1/H.460.13 Example availability and invocation procedures ITU-T Rec. H.460.13 (03/2004) 3 5.2 Called user release control invocation A called H.323 Endpoint shal
35、l invoke called user release control by including a called user release control request (curcRequest or curcRequestNeedAck) in backward messages (Alerting, Call Proceeding, Progress, Connect and Facility messages). If the called H.323 Endpoint sends a curcRequestNeedAck, it shall start a called user
36、 release control acknowledgement timer and await a called user release control acknowledgement (curcAck) from the calling H.323 Endpoint. When a calling H.323 Endpoint receives a called user release control request (curcRequest or curcRequestNeedAck) in a backward message, it shall enter a called us
37、er release control state in which the calling users ability to release a call is disabled. If the calling H.323 Endpoint receives a request to release the call (e.g., the calling user goes on-hook at a H.323 terminal), the H.323 Endpoint shall not initiate release procedures. If the calling H.323 En
38、dpoint receives a called user release control request with acknowledgement required (curcRequestNeedAck), it shall send a called user release control acknowledgement (curcAck) in any H.225.0 call signalling message to the called H.323 Endpoint. When the called H.323 Endpoint receives a curcAck, it s
39、hall stop the called user release control acknowledgement timer and consider the invocation as successful. Expiry of the called user release control acknowledgement timer shall be considered as an unsuccessful invocation of called user release control. Intermediate signalling entities shall relay an
40、y received called user release control request and acknowledgement. 5.3 Called user release control release Figure 2 illustrates the Called User Release Control Release Procedures. After successful invocation of called user release control, the called H.323 Endpoint may release the called user relea
41、se control capability by sending a called user release control release (curcRelease) or a CURC release with acknowledgement required (curcReleaseNeedAck) in any H.225.0 call signalling message to the calling H.323 Endpoint. If a called user release control has been invoked for a connection and the c
42、alling H.323 Endpoint receives a called user release control release (curcRelease or curcReleaseNeedAck), it shall re-enable the ability to release the call from the calling H.323 Endpoint. If the calling H.323 Endpoint receives a curcReleaseNeedAck, it shall send a called user release control relea
43、se acknowledgement (curcReleaseAck) in any H.225.0 call signalling message to the called H.323 Endpoint. When the called H.323 Endpoint receives a curcAck, it shall consider the called user release control release as successful. Intermediate signalling entities shall relay any received called user r
44、elease control release and release acknowledgement. Figure 2/H.460.13 Example called user release control release procedures 4 ITU-T Rec. H.460.13 (03/2004) 5.4 Call termination under called user release control Figure 3 illustrates the disconnect and reconnect procedures. An intermediate entity may
45、 initiate normal call termination procedures regardless of the called user release control state. If the calling user attempts to terminate the call (by going on-hook) while the called user release control is invoked, the calling H.323 Endpoint shall block release of the connection and shall send a
46、user disconnect indication (disconnectInd) in any H.225.0 call signalling message to the called H.323 Endpoint. The called user shall be notified of the calling users disconnect indication. If the calling user reconnects to the call (by going off-hook) while the called user release control is invoke
47、d, the calling H.323 Endpoint shall send a user reconnect indication (reconnectInd) in any H.225.0 signalling message to the called H.323 Endpoint. The called user shall be notified of the calling users reconnect indication. If the called H.323 Endpoint has received a disconnectInd from the calling
48、H.323 Endpoint, it may send an alerting request (alertRequest) to the calling H.323 Endpoint in any H.225.0 signalling message. When the calling H.323 Endpoint receives the alertRequest, it shall notify the calling user with a ringing tone. Intermediate signalling entities shall relay any received d
49、isconnect and reconnect indications and alerting requests. Figure 3/H.460.13 Example disconnect and reconnect procedures 6 Called user release control indications Called user release control indications are transported in the H.225.0 RAS and call signalling (Q.931) messages using the generic extensibility framework. When sending the called user release control indications in the call signalling messages, they shall be coded in the genericData parameter in the H.225.0 H323-UU-PDU in the User-user Information Element. When sending the called user release c
