1、ITU-T RECNN*Q=2957 95 = 4862593 0599694 OST INTERNATIONAL TE LECOMMUN CATION UN ION ITU-T TELECOM M UN CATION STAN DARD IZATI ON SECTOR OF ITU 6-ISDN APPLICATION PROTOCOLS FOR ACCESS SIGNALLING Q.2957 (02/95) STAGE 3 DESCRIPTION FOR ADDITIONAL INFORMATION TRANSFER SUPPLEMENTARY SUBSCRIBER SIGNALLING
2、 SYSTEM No. 2 Clause 1 - User-to-user signalling (UUS) SERVICES USING B-ISDN DIGITAL (DSS 2) - BASIC CALL ITU-T Recommendation Q.2957 (Previously “CCITT Recommendation”) FOREWORD The U-T (Telecommunication Standardization Sector) is a pennanent organ of the International Telecommunication Union (ITU
3、). The ITU-T is responsible for studying technical, operating and tariff questions and issuing Recommen- dations on them with a view to standardizing telecommunications on a worldwide basis. The World Telecommunication Standardization Conference (WTSC), which meets every four years, establishes the
4、topics for study by the ITU-T Study Groups which, in their turn, produce Recommendations on these topics. The approval of Recommendations by the Members of the ITU-T is covered by the procedure laid down in WTSC Resolution No. 1 (Helsinki, March 1-12,1993). -T Recommendation Q.2957, clause 1, was pr
5、epared by ITU-T Study Group 11 (1993-1996) and was approved under the WTSC Resolution No. 1 procedure on the 7th of February 1995, NOTE In this Recommendation, the expression “Administration” is used for conciseness to indicate both a telecommunication administration and a recognized operating agenc
6、y. O ITU 1995 Ali 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 the IT. _ ITU-T RECflN*Q*2957 95 YB6259L 0599696 922 CONTENTS 1 User-to-User Si
7、gnalling (WS) 1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8 1.9 1.10 1.11 1.12 1.13 1.14 Scope References . Definitions Abbreviations Description Operational requirements State definitions Coding Requirements . Signalling procedures at the coincident SB and TB reference point . Procedures for interworking with pr
8、ivate networks . Interworking with other networks Interaction with other supplementary services . Parameter values (timers) . Dynamic description (SDLs) Appendix I . Signalling flows . Appendix II - Instruction indicators Page 1 1 1 2 2 2 2 3 3 6 8 8 9 9 9 9 10 Recommendation Q.2957 (02/95) 1 ITU-T
9、RECMN*d.2957 95 4862592 0599b97 869 m SUMMARY This Recommendation defines the operation of the Digital subscriber Signalling System No. 2 (DSS 2) for the support of the User-to-User Signalling (UUS) supplementary service at the TB or the coincident SB and TB reference point of the user to network in
10、terface of the Broadband-Integrated Services Digital Network (B-ISDN). The User-to-User Signalling (UUS) supplementary service allows a B-ISDN user to send and receive a limited amount of information to/from another B-ISDN user over the signalling virtual channel in association with a calkonnection
11、to the other B-ISDN user. 11 Recommendation Q.2957 (OW95) ITU-T RECMNxQ.2957 95 4862593 0599698 7T5 Recommendation Q.2957 STAGE 3 DESCRIPTION FOR ADDITIONAL INFORMATION TRANSFER SUPPLEMENTARY SERVICES USING B-ISDN DIGITAL SUBSCRIBER SIGNALLING SYSTEM NO. 2 (DSS 2) - BASIC CALL (Geneva, 1995) 1 User-
12、to-User Signalling (UUS) 1.1 Scope This Recommendation specifies the stage three of the User-to-User Signalling (UUS) supplementary service for the Broadband integrated Services Digital Network (B-ISDN) at the TB reference point or coincident S, and TB reference point (as defined in Recommendation 1
13、.413 i) by means of the Digital Subscriber Signalling System No. 2 (DSS 2) protocol. Stage three identifies the protocol procedures and switching functions needed to support a telecommunications service (see Recommendation 1.130 21). In addition, this Recommendation specifies the protocol requiremen
14、ts at the TB reference point where the service is provided to the user via an intermediate private B-ISDN. This Recommendation does not specify the additional protocol requirements where the service is provided to the user via a telecommunications network that is not a B-ISDN. The User-to-User Signa
15、lling (UUS) supplementary service allows a B-ISDN user to sendreceive a limited amount of information to/from another B-ISDN user over the signailing virtual channel in association with a calUconnection to the other B-ISDN user. For N-ISDN services supported in B-ISDN, see Recommendation 1.257.1 5.
16、For B-ISDN services, the applicability has yet to be defined. This Recommendation is applicable to equipment, supporting the UUS supplementary service, to be attached at either side of a TB reference point or coincident SB and TB reference point when used as an access to the public B-ISDN. 1.2 Refer
17、ences 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. AU Recommendations and other references are subject to revision; all u
18、sers 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 Recornendation 1.413 (1993), B-ISDN user
19、-nehuork interfaces. CCITT Recommendation I. 130 (1988), Method for the characterization of telecommunication services supported by an ISDN and network capabilities of an ISDN. ITU-T Recommendation Q.293 1 (1993, Broadband-Integrated Services Digital Network (B-ISDN) - Digital Subscriber Signalling
20、No. 2 (DSSL) - User-network integ5ace layer 3 specification for basic calliconnection control. CCITT Recommendation E.164 (1991), Numbering plan for the ISDN era. CCITT Recommendation 1.257.1 (1992), User-to-user signalling. CCITT Recommendation X.213 (1992), Information technology - Network service
21、 definition for Open Systems interconnection (OSI). IT-T Recommendation 1.580 (1993), General arrangements for interworking between B-ISDN and 64 kbitls based ISDN. Recommendation Q.2957 (02/95) 1 ITU-T RECMN*Q.2957 95 48b259L 0599699 631 1.3 Definitions For the purposes of this Recommendation, the
22、following definitions apply: 13.1 user: The DSS 2 protocol entity at the user side of the user-network interface. 13.2 network: The DSS 2 protocol entity at the network side of the user-network interface. 1.3.3 called user: The user who is offered an incoming callkonnection at the termbating interfa
23、ce. 1.3.4 calling user: The user who initiates an outgoing call/connection at the originating interface. 1.3.5 served user: The user requesting the User-to-User (rnrS) supplementary service. 1.4 Abbreviations For the purposes of this Recommendation, the following abbreviations are used: B-ISDN DSS 2
24、 ISDN integrated Services Digital Network N-ISDN UUS User-to-User Signalling UUI User-to-User Information Broadband Integrated Services Digital Network Digital Subscriber Signaihg System No. 2 Narrow-band integrated Services Digital Network 15 Description The UUS supplementary services provide a mea
25、ns of communication between two users by using as a basis the layer 3 protocol defined in clause VQ.2931 3. User-to-user signalling is used to exchange information between two users to provide the services described in the Stage 1 Service Description. The exchange of user-to-user signalling is limit
26、ed by flow control procedures provided by the network or the user. The exchange of user-to-user information is not a network acloiowledged service. Any achowledgement procedure shall be controlled at a higher layer between users. Three WS services associated with B-ISDN calls that may be provided by
27、 the network to users are: a) Service I - User-to-user information exchanged during the Set-up and clearing phases of a cail/connection, by transporting the User-user information element within Recommendation 4.293 1 3 cd/connection control messages; Service 2 - User-to-user information exchanged fr
28、om the senders point of view during calvconnection establishment, between the ALERTING and CONNECT messages, within USER INFORMATION messages; and b) c) Service 3 - User-to-user information exchanged while a call/connection is in the Active state, within USER INFORMATION messages. AU three services
29、may be used separateiy or in any combination in association with a single call. As an option, at call/connection Set-up, users may be able to specify that the requested user-to-user signalling service(s) is (are) required for the call, i.e. the call should not be completed if user-to-user informatio
30、n cannot be passed. For B-ISDN Release 1, only WS service 1 (implicitly requested) is specified and supported. S service 1 (explicitly requested), UUS service 2 and UUS service 3 are outside the scope of this Recommendation. 1.6 Operational requirements 1.6.1 Provis iodwit bdraw ai UUS service 1 mus
31、t be subscribed to by the calling user. 2 Recommendation Q.2957 (02/95) ITU-T RECMN*Q*2757 75 48b259L 0599700 LB3 = 1.6.2 The basic cail/connection control procedures according to 5.UQ.2931 and 5.4/Q.2931 3 are applicable. Requirements on the originating network side 1.6.3 The basic caii/connection
32、control procedures according to 5.WQ.2931 and 5.4/Q.2931 3 are applicable. Requirements on the destination network side 1.6.4 Terminal equipment using WS service 1 is expected to be able to generate and accept the User-user information element (see 1.8.3) as described in 1.9 below. Assumptions made
33、about the terminal 1.7 State definitions The states associated with basic cWconnection control according to Recommendation Q.293 1 3 are applicable, 1.8 Coding Requirements 1.8.1 Messages The following messages are applicable to the operation of service 1: SETUP, ALERTING, CONNECT, REEASE, RELEASE C
34、OMPLETE, PROGRESS. Tables 1-1 to 1-6 show the message contents for WS service 1 implicit. 1.8.2 Codesets The UUS supplementary service information elements are in codeset O. 1.8.3 Information elements The User-user information element is applicable to the operation of service 1. The purpose of the U
35、ser-user information element is to convey information between B-ISDN users. This information is not interpreted by the network, but rather is carried transparently and delivered to the remote user(s). The User-user information element shall be considered as an access information element (see Annex J
36、/Q.2931 3). TABLE 1-1/Q.2957 Contents of ALERTING message Message type: ALERTING NOTE -May be included for UUS service 1 (implicit activation). Recommendation Q.2957 (02/95) 3 ITU-T RECflN*Q-2757 95 Y86259L 0597703 OLT m Information element Protocol discriminator TABLE 1-2/Q.2957 Contents of CONNECT
37、 message Reference Direction Type Length 4214.2931 Both M 1 Message type: CONNECT Caii reference Message type Message length User-user 4.3JQ.293 1 Both M 4 4.4.1JQ.2931 Both M 2 4.4.2JQ.293 1 Both M 2 1.8.3 Both O (see Note) 4-133 NOTE -May be included for UUS service 1 (implicit activation). Not in
38、cluded otherwise. 1 TABLE 1-3/Q.2957 Contents of RELEASE message NOTE -May be included for UUS service 1 (implicit activation). Not included otherwise. 4 Recommendation Q.2957 (02/95) ITU-T RECMN*Q=2957 95 4862571 0599702 T5b W information element Protocol discriminator Cali reference Message type M
39、essage length User-user TABLE 14/Q.2957 Contents of RELEASE COMPLETE message Reference Direction Type Length 4.U4.2931 Both M 1 4314.293 1 Both M 4 4.4.1/Q.2931 Both M 2 4.4.214.2931 Both M 2 1.8.3 U+N O (see Note) 4-133 Message type: RELEASE COMPLETE NOTE - May be included for UUS service 1 where a
40、 RELEASE COMPLETE message is sent by the user to reject an incoming SETUP message. Not included otherwise. TABLE 1-5/Q.2957 Contents of SETUP message Message type: SETUP Recommendation Q.2957 (02/95) 5 ITU-T RECMN*Q-2957 95 48b2591 0599703 992 Ext TABLE 1-6/Q.2957 Contents of PROGRESS message standa
41、rd Flag Reserved Action indicator Message type: PROGRESS per Recommendation 4.2931 3 The coding for the User-user information element is shown in Figure 1-1. Bits 8 7 6 5 4 3 2 1 User-user O 1 1 1 1 1 1 O I information element identifier I I 1 I Coding I IE Instruction field I Further contents as in
42、 Figure 4-36/Q.931 and Table 4-26KJ.931 1 Octet 1 2 1 3,4 i5 FIGURE 1-1/Q.2957 User-user information element 1.9 Signalling procedures at the coincident SB and TB reference point 1.9.1 Activatioddeactivatiodregistration Service 1 shall be activated implicitly as described in 1.9.2 below. In this cas
43、e, activation and operation of the service are indistinguishable. The procedures for call establishment are described in Recommendation Q.2931 3 with the following modifications. On call request, the SETUP message sent by the calling user shaii contain the service 1 request, i.e. the User-user infor
44、mation element. 6 Recommendation Q.2957 (02/95) The SETUP message sent by the network towards the called user shall also contain the same service requests, i.e. the User-user information element, Deactivation procedures are not required to support service 1 implicit. 1.9.2 Call establishment phase -
45、Implicit operation 1.9.2.1 Normal operation Service 1 may be implicitly requested by including a User-user information element of variable length as specified in 1.8.2 in the SETUP message, transferred across the user-network interface at the calling side as described in 5.1.1/Q.2931 3. This informa
46、tion element is transported by the network and delivered unchanged in the User-user information element included in the SETUP message transferred across the user-network interface at the called side as described in 5.2.UQ.2931 3. For activation purposes, this information element must be at least fiv
47、e octets long, as defined in 1.8.3. A User-user information element may be included in the ALERTING and/or CONNECT messages transferred across the user-network interface at the called side as described in 5.2.YQ.2931 3. It may also be included in the RELEASE or RELEASE COMPLETE message (see 1.9.3).
48、The content of this information element is transported by the network and delivered in the User-user information element included in the corresponding message(s) transferred across the user- network interface at the calling side as described in 5.1.WQ.2931 and 5.1.7/Q.2931 3. NOTE - In accordance wi
49、th the Network Service Defmition for Open Systems Interconnection, IS0 8348 I Recommendation X.213 6, the called user may perform compatibility checking using the User-user information element contents (see Annex B/Q.2931 3). In the context of the OS1 Network Service, service 1 may be used to support the conveyance of the NS-User-Data parameter of the N-CONNECT and N-DISCONNECT primitives. 1.9.2.2 Exceptional procedures The network shall discard the User-user information element if it is received from the calling user in a SEL.JP message,
