1、CEPT T/CS*ZO-OL*E 0 I 2326414 0004499 3 I- 4 20-01 Page 1 E Recommendation T/CS 20-01 (Brussels 1980, revised in Innsbruck 1981 and Vienna 1982) EXCHANGE AND NETWORK FEATURES Recommendation proposed by Working Group T/WG 11 “Switching and Signalling” (CS) Revised text of the Recommendation adopted b
2、y the “Telecommunications” Commission: “The European Conference of Postal and Telecommunications Administrations, considering - the existing variety of systems and interworking procedures in the networks of the member countries; - the many new possibilities offered by the advanced technologies, in p
3、articular digitalisation, fast switching, stored program control and common channel signalling; - that these new possibilities result in an increasing demand to expand the services provided by Telecommunications Administrations ; O - - that network capabilities with respect to services could be harm
4、onised by establishing functional consistency of systems and interworking procedures; - that Co-ordinated flexible use of a comprehensive and harmonised set of service oriented network capabilities could result in a relatively stable network, assuring compatible interconnection even of an increased
5、variety of customer terminals, recommends that members of the CEPT, when developing and introducing new systems and interworking procedures relating to services, adopt the concept of exchange and network features outlined below.” 1. GENERAL 1.1. The provision of services is dependent upon the availa
6、bility of certain features, provided either by individual exchanges or other parts of the network, such as the signalling systems. The combination of features required to provide a service may be wholly resident in one exchange or they may be distributed between two or more exchanges. In the latter
7、case, the features in the different exchanges must conform to a common performance specification if they are to work together, and their activation must be Co-ordinated by suitable inter-exchange signals (see Figure 1 (T/CS 20-01). 1.2. Note: The studies on this series (T/CS 20) of Recommendations f
8、or the features in an analogue environment has now been terminated. A continuation of the studies has started with the aim to amend these existing features, where necessary, and to specify new features for the ISDN. These Recommendations will be gathered in a new series of Recommendations. Edition o
9、f May 15, 1986 CEPT T/CS*ZO-OL*E 0 2326414 0004500 b T/CS 20-01 E Peg0 2 . 1.3. By designing exchanges and networks to contain a harmonised list of features satisfying a common performance specification, the possibility of introducing supplementary services on any national or interna- tional call be
10、tween the exchanges is assured. 2, 3, 3,1, 3,2. 3.3. 3,4. CALL FROM A TO B INVOLVING MCI q=jL)-+-(+fi AUTOMATIC NUMBER I DE NTI FI CATI ON U F EATU R E t AN EXCHANGE FEATURE ADDITIONAL SIGNALLING F EATU R E I A NETWORK FEATURE MCI: MALICIOUS CALL IDENTIFICATION 1 LINESERVICE 1 MARKING RECALL OR SPEC
11、IAL SIGNAL I SU BSCR I BERS D ED I CATE D STO RAG E FEATURE Figure 1 (T/CS 20-01). An illustration of the network distribution of system features required to provide a service. OBJECTIVES The principal objectives in defining exchange and network features are: (a) to aid the harmonisation of system i
12、ndependent switching functions between exchanges of differing designs and manufacture; (b) to aid in the harmonisation of interworking standards between switching systems located in different countries ; (c) to assist CEPT Working Groups in their discussion of service requirements; (d) to provide in
13、formation for the preparation of functional specifications for new services, to maximise the exploitation of features provided and available in switching systems. DEFINITIONS System feature A system feature is one inherent characteristic or ability of either an exchange (exchange feature) or of a pa
14、rticular part of the network (network feature) that is required before the total system actions can make up one or more of the basic or supplementary services. Exchange feature An exchange feature is a system feature located entirely within one exchange. An example of an exchange feature is automati
15、c number identiJication (ANI). This feature may be used in various supplementary services such as malicious call identiJication and completion of culls to busy sub- scribers, Such a feature may be provided by hardware, software, or a combination of both. Network feature A network feature is a system
16、 feature, such as signalling, providing interworking between exchanges. An example of a network feature is additional signalling. This feature may be used in various supplementary services such as three-party service and malicious call identiJication. Independent service An independent service is a
17、service whose features can always be located in only one exchange, thus allowing that exchange to provide the service independent of the ability of other exchanges. -_- Edition of May 15, 1986 3.5. 4. 4.1. 4.2. 4.3. 4.4. 5. 5.1. 5.2. 5.3. 5.4. I. CEPT T/CS*20-01*E 80 I 2326434 0004503 I TICS 20-01 E
18、 Page 3 Co-operative service A co-operative service is a service which (on call routings involving more than one exchange) requires features to be located in more than one of the exchanges in the call routing, and furthermore, requires these features to act in co-operation with each other. Services
19、of this type always involve network features. THE USE OF SYSTEM FEATURES IN SYSTEM DESIGN The individual system feature usually contributes only a part of any one service, and it must work in conjunction with other features to provide the complete service. Conversely, a telecommunications system can
20、 provide a service only if it contains all the features necessary for that service at appropriate locations. The analysis of the features required for services can be used to ensure that the specifications for new apparatus, exchange equipment, or signalling systems, call for all the features necess
21、ary for the services to be provided, and that these features will be put in the most effective locations. Not only will this avoid unnecessary duplication of features, but, by choosing the optimum location for each feature, signalling activities and post-dialling delays can be minimised. When consid
22、ering adding a new service to an existing system, knowledge of the features already available in that system and their location makes it possible to design the new service to maximise the use of existing features. This, in turn, will minimise changes to the system necessary for introducing the propo
23、sed service. The standardisation of system features is thus conductive to the harmonisation of system design. ANALYSIS OF SERVICES TO IDENTIFY FEATURES An analysis of each proposed service to identify the features required, and the various methods by which the service might be provided by the system
24、, will allow possible locations for each feature to be identified. An analysis of the total feature requirements for all services proposed will then allow the optimum distribution of features in the network to be determined. The optimum feature locations will be affected both by the characteristics
25、of theservices needing the feature and by the precise nature of the task performed by that feature. Thus, some tasks are closely linked to the “A” subscribers termination, while others are linked to the “B” subscribers termination, Furthermore, for independent services, the required features can all
26、 be located at one end of the call, while for Co-operative services some features will be required at each end and others along the routing of the call. Many supplementary services involve two distinct sets of system actions : (a) actions concerned with the control of the service when the subscriber
27、 may instruct the system to activate or deactivate the service, register information with respect to the service, or to interrogate the system about the state of the service; (b) actions concerned with the use of the service and occurring when the system handles a call in accordance with the require
28、ments for that service. For every service, each of these two sets of system actions will usually involve different sets of features, and it is necessary to identify both sets in order to determine the features required to provide a given service. The features necessary for each service for control a
29、nd use purposes are shown in a Table (see Appendix). - Edition of May 15, 1986 .I TICS 20-01 E Page 4 Appendix The table mentioned in this Recommendation is under study. However, the provisional table below is given for information. Exchange and network features required (see list below) A. Comfort
30、for calling party services (1) Abbreviated dialling (2) Call progress information (Tones, announcements, visual indications) (3) Call charge information (4) Fixed destination calls (5) Cheap access calls (Service 800 functions) (6) Completion of calls to busy subscriber (7) Service restriction in th
31、e outgoing direction (i) Call diversion (2) Call interception (3) Call waiting (4) Calling line identification C, Three-party service B. Comfort for called party services 1, 2, 4, 7, 9 43 2, 3, 4, 7, 9, 13, 14 2, 4, 9, 14 not yet analysed 1, 2, 3, 4, 7, 8, 9, 11, 14 1, 2, 4, 7, 9 I, 2, 4, 5, 7, 8, 9
32、, 10, 14 1, 2, 4, 7, 8, 9, 14 1,2,3,4,8, 13, 15, 16 2, 3, 4, 7, 8, 9, 14, 17 2, 3, 4, 8, 9, 11, 12, 13, 14, 15 D. Alarm call service 1, 2, 4, 6, 7, 8, 14 E. Conference call service F. PBX service 1, 2, 3, 4, 8, 9, 12, 13, 14 1, 2, 4, 5, 6, 8, 9, 14 G. Mobile telephone H. Closed user group service no
33、t yet analysed not yet analysed FEATURE (1) Push-button dialling (2) Line service marking (3) Register recall (4) Tones and announcements (5) Analogue subscribers line hunting (6) Direct dialling-in signalling (7) Automatic number identification (8) Additional signalling (9) Subscriber dedicated sto
34、re (10) Call diversion (1 1) Diversion of charge (12) Special bridge (13) Hold (14) Real time clock (15) Connection splitting (16) Tone injection (17) Special subscribers signal (18) Message recording RECOMMENDATION T/CS 46-02 and 46-03 T/CS 20-05 T/CS 20-09 T/CS 20-15 T/CS 20-1 1 T/CS 20-22 T/CS 20-06 T/CS 20-26 T/CS 20-07 T/CS 20-25 T/CS 20-19 T/CS 20-18 T/CS 20-20 , . Edition of May 15, I 1986
