1、_ ITU-T RECMN*Q-954 95 9 4862591 0616615 605 W I l INTERNATIONAL TELECOMMUNICATION UNION l ITU-T TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU Q.954 (1 0/95) DIGITAL SUBSCRIBER SIGNALLING SYSTEM No. 1 INTEGRATED SERVICES DIGITAL FOR MULTIPARTY SUPPLEMENTARY SERVICES USING DSS 1 NETWORK (ISDN) - ST
2、AGE 3 DESCRIPTION CLAUSE 2 - THREE PARTY (3PTY) ITU-T Recommendation Q.954 (Previously “CCIlT Recommendation”) ITU-T RECMN*d.354 75 4862591 ObLbbLb 541 = FOREWORD The ITU-T (Telecommunication Standardization Sector) is a permanent organ of the International Telecommunication Union (ITU). The ITU-T i
3、s 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 topics for stu
4、dy 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). IT-T Recommendation 4.954, clause 2, was revised by ITU
5、-T Study Group 11 (1993-1996) and was approved under the WTSC Resolution No. 1 procedure on the 17th of October 1995. NOTE In this Recommendation, the expression “Administration” is used for conciseness to indicate both a telecommunication administration and a recognized operating agency. O ITU 1996
6、 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 the ITU. ITU-T RECMN*Q.754 75 4862.591, ObLbbL7 Y88 CONTENTS 2 Three-party (3PTY) 2.1 Scope
7、2.2 References . 2.3 Definitions 2.4 Abbreviations 2.5 Description 2.6 Operational requirements 2.7 Coding requirements . 2.8 State definitions 2.9 Signalling requirements 2.10 Procedures for interworking with private ISDNs . 2.1 1 Interactions with other networks . 2.12 Interactions with other supp
8、lementary services 2.13 Parameter values (timers) . 2.14 Dynamic description (SDLs) Appendix I - Signalling flows . Request for a three-way conversation . Disconnection of one remote user, and retention of the other Disconnection of both remote users and terminating the call . Creation of a private
9、communication with a remote user . Remote user terminates the call 1.1 1.2 1.3 1.4 1.5 Recommendation Q.954 (10/95) Page 1 1 1 2 3 3 4 4 4 5 11 11 12 15 15 27 28 28 30 32 33 1 SUMMARY This Recommendation defines the operation of the Digital Subscriber Signalling System No. 1 (DSS 1) for the support
10、of the Three-Party (3PTY) supplementary service at the T or the coincident S and T reference point of the Integrated Services Digital Network (ISDN). The Three-Party supplementary service allows the user to establish, participate in, and control a three-way conversation, i,e. simultaneous communicat
11、ion involving the served user and two remote users. 11 Recommendation Q.954 (10/95) ITU-T RECMNrQ-954 75 4862573 ObLbbL9 250 M Recommendation Q.954 INTEGRATED SERVICES DIGITAL NETWORK (ISDN) - STAGE 3 DESCRIPTION FOR MULTIPARTY SUPPLEMENTARY SERVICES USING DSS 1 (revised in 1995) 2 Three-party (3PTY
12、) 2.1 Scope This Recommendation specifies stage three of the Three-Party (3FTY) supplementary service for the Integrated Services Digital Network (ISDN) at the T reference point or coincident S and T reference point (as defined in Recommen- dation 1.41 1 i) by means of the Digital Subscriber Signall
13、ing System No. 1 (DSS 1) protocol. Stage three identifies the protocol procedures and switching functions needed to support a telecommunications service (see Recommen- dation 1.130 2). In addition, this Recommendation specifies the protocol requirements at the T reference point where the service is
14、provided to the user via an intermediate private 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 an ISDN. The 3PTY supplementary service enables a user to establish, participate in
15、and control, a three-way conversation, i.e. a simultaneous communication involving the served user and two remote users. The 3PTY supplementary service is applicable to all circuit-switched telecommunication services carrying speech. This Recommendation is applicable to equipment, supporting the 3PT
16、Y supplementary service, to be attached at either side of a T reference point or coincident S and T reference point when used as an access to the public ISDN. 2.2 References The following Recommendations and other references contain provisions which, through reference in this text, constitute provis
17、ions of this Recommendation. At the time of publication, the editions indicated were valid. All Recommendations and other references are subject to revision: all users of this Recommendation are therefore encouraged to investigate the possibility of applying the most recent edition of the Recommenda
18、tions and other references listed below. A list of the currently valid IT-T Recommendations is regularly published. i ITU-T Recommendation 1.41 1 (1993), ISDN user-network interfaces - Reference configurations. 2 CCITT Recommendation I. 130 (1988), Method for the characterization of telecommunicatio
19、n services supported by an ISDN and network capabilities of an ISDN. 3 ITU-T Recommendation 4.93 1 (1993), Digital Subscriber Signalling System No. 1 (DSS I) - ISDN user-network interface layer 3 specification for basic call control. 4 CCITT Recommendation Q.9 (1988), Vocabulary of switching and sig
20、nalling terms. 5 ITU-T Recommendation Q.920 (1993), Digital Subscriber Signalling System No. I (DSS i) - ISDN user-network interface data link layer - General aspects. 6 ITU-T Recommendation I. 112 (1993), Vocabulary of terms for ISDNs. 7 ITU-T Recommendation Q.932 (1993), Digital Subscriber Signall
21、ing System No. 1 (DSS 1) - Generic procedures for the control of ISDN supplementav services. Recommendation Q.954 (10/95) 1 ITU-T RECMN*Q.954 95 4Bb259L 0636620 T72 ITU-T Recommendation Q.952l). Stage 3 description for call offering supplementary services using DSS 1. Clause 7 - Explicit Call Transf
22、er (ECT). CCITT Recommendation X.219 (1988), Remote operations: Model, notation and service definition. ITU-T Recommendation 1.210 (1993), Principles of telecommunication services supported by an ISDN and the means to describe them. CCITT Recommendation X.208 (1988), Specification of Abstract Syntax
23、 Notation One ASN. I). ITU-T Recommendation Z. 1 O0 (1993), CCZT Specification and Description Language (SDL). -T Recommendation Q.953 (1993), ISDN Stage 3 description for call completion supplementary services using DSS 1. Clause 2 - Call Hold. IT-T Recommendation Q.956 (1995). Integrated Services
24、Digital Network (ISDN) - Stage 3 description for charging supplementary services using DSS I. Clause 2 -Advice of Charge (AOC). ITU-T Recommendation 4.955 (1993), Stage 3 description for communi0 of interest supplementary services using (DSS 1). Clause 3 - Multilevel precedence and preemption (MLPP)
25、. Definitions For the purposes of this Recommendation, the following definitions apply: 2.3.1 the auxiliary state is Call Held. 2.3.2 the auxiliary state is Idle. 2.3.3 call state: A state as defined in 2. UQ.93 1 3 for either the user side or the network side as appropriate. A call state may exist
26、for each Call Reference (CR) value and for each additional responding Connection Endpoint Identifier (CEI) in the incoming call state. 2.3.4 call: See 2.2/Q.9 4, definition 2201. 2.3.5 connection endpoint identifier (CEI): The identifier that identifies the data link connection which is used to tran
27、sfer the signalling information (for the complete definition see 3.4. UQ.920 5. 2.3.6 connection: See clause OlQ.9 4, definition O01 1. 2.3.7 integrated services digital network (ISDN): See 2.3fi.112 6, definition 308. 2.3.8 invoke component: See 6.31Q.932 7 for the application of this component as
28、defined in Recommenda- tion X.219 9. Where reference is made to “xxxx” invoke component, an invoke component is meant with its operation value set to the value of the operation “xxxx”. 2.3.9 local interaction: An interaction of the protocol for two or more supplementary services where the served use
29、r (of all supplementary services) is on the same access. 2.3.10 local interaction for the call: The local interaction exists on a single call, i.e. both supplementary services are invoked for the same call. 2.3.11 network: The DSS 1 protocol entity at the network side of the user-network interface.
30、2.3.12 no impact: The interaction between the two identified supplementary services contains no requirements for the protocol over and above the requirements of the Recommendation for each individual supplementary service. NOTE - Other aspects of interactions that do not affect the DSS 1 protocol ar
31、e covered in the service description for the relevant supplementary services. 2.3.13 not applicable: The interaction between the two identified supplementary services is outside the scope of this Recommendation, e.g. the interaction is between the supplementary service and itself, and is therefore c
32、overed in the Recommendation for the individual supplementary service. active-held connection: A connection between two users where at the served user, the call state is Active, and active-idle connection: A connection between two users where at the served user, the call state is Active, and *) Pres
33、ently at the stage of draft. 2 Recommendation Q.954 (10/95) ITU-T RECMN*6!*954 75 9 4862573 0636623 707 2.3.14 communication with the other remote user. private communication: Communication between the served user and one remote user. This excludes 2.3.15 tion X.219 9. 2.3.16 remote interaction: An
34、interaction of the protocol for two or more supplementary services where one user is the served user for one supplementary service and (for the same call) the remote user for another supplementary service. The interaction for the served users supplementary service exists at the remote user. 2.3.17 t
35、ogether in a three-way conversation. The remote users are distinguished as user B and user C. 2.3.18 return error component See 6.3/Q.932 7 for the application of this component as defined in Recommendation X.219 9. Where reference is made to “xxxx” return error component, a return error component i
36、s meant which is related to an “xxxx” invoke component. 2.3.19 return result component: See 6.3/Q.932 7 for the application of this component as defined in Recommendation X.219 9. Where reference is made to “xxxx” return result component, a return result component is meant which is related to an “xx
37、xx” invoke component. 2.3.20 referred to as user A. 2.3.21 2.3.22 2.3.23 2.3.24 way conversation. 2.3.25 reject component: See 6.3/Q.932 7 for the application of this component as defined in Recommenda- remote user: The two other users to the served user which are involved in the two calls that are
38、joined served user: The user (DSS 1 protocol entity) which invokes this supplementary service; this user is also service; telecommunications service: See 2.2/1.112 6, definition 201. supplementary service: See 2.4n.210 101. three-way conversation: Communication between ali three users, i.e. the serv
39、ed user and both remote users. three-way bridge: The network equipment which performs connections between three users to allow three- user: The DSS 1 protocol entity at the user side of the user-network interface. 2.4 Abbreviations For the purposes of this Recommendation, the following abbreviations
40、 are used: 3PTY Three-Party ASN. 1 CE1 Connection Endpoint Identifier CR Call Reference DSS 1 ISDN Integrated Services Digital Network PSTN Public Switched Telephone Network SDL Specification and Description Language Abstract Syntax Notation one Digital Subscriber Signalling System No. 1 2.5 Descrip
41、tion The served user, which has only one Active-Idle connection, and at least one Active-Held connection can join the Active-Idle connection with one of the Active-Held connections, to form a three-way conversation. NOTES 1 by the appropriate remote user. Each call, to be involved in the 3PY supplem
42、entary service, could have been originated by either the served user, or During the three-way conversation the served user can request that the network - - - explicitly disconnects one of the remote users, and the connection to that remote user; terminates the three-way conversation; or creates a pr
43、ivate communication with one of the remote users, Recommendation Q.954 (10/95) 3 ITU-T RECMN*d.954 95 W 4862571 06116622 845 Either of the remote users (user B or user C) can request that the network disconnects the connection. Remote users are notified of these actions. 2 3 During an interim period
44、 of time, some networks may not support the transfer of the notification to the remote users. The protocol for implementation of the 3PT supplementary service is restricted to implementations where only one call within an Active-Idle connection exists for that CE1 value. User implementations, e.g. m
45、ultifunctional terminals, that in a normal operation support more than one call with an Active-Idle connection on the same CE1 value, cannot make effective use of this protocol. 2.6 Operational requirements 2.6.1 Provision and withdrawal The 3FTY supplementary service shall be provided by prior arra
46、ngement with the service provider. The 3pTY supplementary service shall be withdrawn by the service provider upon request of the subscriber or for service provider reasons. 2.6.2 The requirements of 5.UQ.931 3 shall apply. 2.6.3 The requirements of 5.2/Q.931 3 shall apply. Requirements on the origin
47、ating network side Requirements on the destination network side 2.7 Coding requirements 2.7.1 Table 2-1 shows the definition of the operations and types required for the 3PTY supplementary service using ASN.1 as defined in Recommendation X.208 I I and using the OPERATION macro as defined in Figure 4
48、K.219 9. The formal definition of the component types to encode these operations and types is provided in Table 8-6/Q.932 7. The inclusion of components in Facility information elements is defined in 8.2.2/Q.932 7. Coding of the Facility information element components All components (invoke, return
49、result, return error and reject) shall be included within a Facility information element. The Facility information element shall be included in the message as specified in 2.9. 2.7.2 The notification description is contained in octet 3 of the Notification indicator information element and shall be coded as shown in Table 2-2. NOTE - The following guidance is given for the interpretation of the notification descriptions at a remote user. A notification description of “Remote hold“ indicates a lo
