1、INTERNATIONAL TELECOMMUNICATION UNION)45G134 1 TELECOMMUNICATIONSTANDARDIZATION SECTOROF ITU%.%2!,G0G02%#/-%.$!4)/.3G0G0/.G0G04%,%0(/.%37)4#().G0G0!.$G0G03).!,).).4%2.!4)/.!,G0G0!54/-!4)#G0G0!.$3%-)G13!54/-!4)#G0G07/2+).!54/-!4)#G0G037)4#().G0G0(2) the continuous rapid development of new switching t
2、echniques results in different generations ofequipment having to co-exist;(3) that some degree of compatibility in the installed switching equipment is required in the world-wideautomatic network;(4) that the introduction of newly developed switching systems presents Administrations with an everincr
3、easing number of engineering, staff training, maintenance and other operational considerations,and also considering(5) that Recommendations originally intended for international application only are increasingly beingapplied to national networks, or could be so applied;(6) that many current studies
4、are aimed at producing Recommendations primarily applicable to nationalnetworks,recommendsthe following guidelines for use by Administrations establishing national switching standards or, if desired, forupdating existing standards. Each Administration may select those guidelines it deems applicable
5、to its own situation.2 Automatic switching functions for use in national networksTable 1/Q.4 lists the functional switching capabilities of an exchange which will, or may in some instances,according to the role of the exchange in a network, need to be technically specified in order that the Administ
6、rationconcerned can be assured that the exchange will satisfy existing and foreseen future needs of the network. For therequired capabilities, references are given to CCITT texts which should be taken into account when decisions onnational standards are taken; some make positive recommendations, oth
7、ers give guidelines or background information.Table 2/Q.4 provides full titles for those referenced texts, and for others applicable to national switching, in order toprovide more specific information about the subject matter.Some of the functions listed are required in all types of exchanges. Other
8、s may or may not be, according to therole of the exchange, e.g. local, combined local/transit, transit, international, etc.It is not always necessary that a precise technical specification be given, e.g., in a tender specification, for eachswitching function. In some instances, it may be sufficient
9、to state the requirements broadly, possibly including desiredranges of parameter values, and to invite a tenderer to make his own specific proposals for evaluation.3 Requirements for ISDNAs Recommendations for the ISDN are being developed concurrently, it is difficult to reference them in thisRecomm
10、endation. All Recommendations relevant to the ISDN will be published in a single volume at the end of thisStudy Period 1981-1984 (Fascicle III.5).2 Fascicle VI.1 - Rec. Q.44 Requirements other than automatic switching functionsThe technical specifications of the required automatic switching function
11、s of an exchange do not, inthemselves, consitute a complete specification. Other aspects possibly needing to be covered, which are particular to anexchange or to a group of exchanges and not included within the scope of automatic switching functions are:- traffic (dimensioning and service performanc
12、e);- specifications dictated by the equipment environment (building constraints, power supplies, climaticconditions, etc.);- installation, including testing, acceptance, post-acceptance technical support, etc.;- training and documentation;- support of system design and software, e.g., CCITT Recommen
13、dation Z.100 (SDL) series and CCITTRecommendation Z.200 (CHILL) series.5 Technical cooperation possibilitiesThe CCITT Recommendations already established so far do not themselves suffice to cover all the points of aspecification dealing with the functions to be performed by switching equipment. It i
14、s unavoidable, if nationalstandards are to match the requirements and circumstances of a particular network, that the responsible Administrationitself exercise a number of choices.An Administration seeking advice or guidance beyond that indicated in CCITT texts may, by approaching theITU Secretariat
15、, obtain information on the standards adopted by other Administrations.6 Definition of requirements in terms of services and facilities6.1 Fundamental decisions as to range of service(s) and facilities to be provided must be made by theAdministration. Descriptions and other information on the variou
16、s services normally provided by a switching systemmay be found as indicated in the following:- types of services (GAS 6, Chapter II, 3; Chapter III, 3.2),- basic services (GAS 6, Chapter IV, 1.2),- supplementary services (GAS 6, Chapter IV, 1.4); Recommendations E.130, E.132, E.151; SupplementNo. 1
17、to Series E Recommendations.6.2 A list of possible telephony subscriber services and facilities has been extracted from the GAS 6 Handbook,Chapter IX, 1.3.2 and is shown in Annex A.Fascicle VI.1 - Rec. Q.4 3TABLE 1/Q.4CCITT texts (Recommendations and GAS Handbooks) relevant to the technical specific
18、ation of automaticswitching functions of exchanges in national networksItem ReferenceA. SwitchingType of switch: analogue (2- or 4-wire)/digital, space or time divisionType of control: distributed/centralizedSubscriber classificationB. Routing and selectionClassification of exchange inlets and outle
19、ts: according to types ofinter-exchange circuits to be connected: taking into account the line,inter-register, etc., signalling arrangements and the transmission,operating, testing, network management, etc., requirementsNumber analysis functions: required capacity and depth of analysisfor routing, d
20、etermination of number length, barring, digitinsertion/deletion, charging, echo control, etc.Choice of outgoing circuit: search procedure, dual seizures, alternativerouting, repeat attempts, etc.Network management functions: circuit group denial, alternativerouting cancellation, exchange load contro
21、l, etc.C. ChargingMethods: local, long-distance, international,non-chargeable, payphone, etc., callsCharge determination: principles and parametersD. Transmission characteristicsInterfaces: specification of the transmission characteristics of theinterfaces, or the identification of the standard inte
22、rfaces, at whichthe exchange is to interconnect with external facilities and systemsExchange transmission performance: Limits for the levels oftransmission impairments attributable to the exchange and forcharacteristics affecting performance, taking account of all possibletypes of connection through
23、 the exchangeE. Synchronization and timingF. Tones and recorded announcementsScope and applications; tones; announcementsGAS 6 II 1, VI 1.1GAS 3 III, Annex 1Recs. Q.501, Q.511GAS 6 VI 1.2GAS 6 VI 1.2.1GAS 6 IV 5.6-7VI 1.4.1 and 4Recs. E.543Q.7, Q.48, Q.49, Q.108, Q.110,Q.251-Q.300, Q.310-Q.331, Q.40
24、0-Q.480,Q.501-Q.507, Q.511-Q.517GAS 6 IV 6, VI 1.4.6Recs. E.160, E.161, E.163Q.103, Q.105, Q.106, Q.107, Q.107 bis,Q.115GAS 6 VI 1.4.2, 3 and 5Recs. E.170, E.171Q.12, Q.263GAS 6 VI 1.4.7Recs. E.170, E.410, E.411, E.412, E.413Q.506, Q.516GAS 6 IV 7.1-2, VI 1.5.1Recs. E.230-E.232GAS 6 IV 7.3, VI 1.5.2
25、GAS 3 IIIRecs. G.703, G.704, G.705, G.731-G.739,G.741-G.746,Q.502, Q.512GAS 6 VI 1.8Recs. G.121, G.122, G.123Q.45, Q.507, Q.517Recs. G.811, G.822Q.502, Q.503, Q.512, Q.513GAS 6 VI 1.7Recs. E.180 (Q.35), E.181 (Q.36), E.182Supplement No. 2 toSeries E RecommendationsRec. Q.244 Fascicle VI.1 - Rec. Q.4
26、TABLE 1/Q.4 (cont.)Item ReferenceG. Subscriber line characteristics1. Analogue subscriber lineSubscriber line standards: limits for loop resistance, loopinsulation, overall line attenuation, etc.Subscriber line signals supervision address information, ringing,metering, tones, etc.2. Digital subscrib
27、er lineExchange interfaces signalling for digital accessH. Inter-exchange signallingSpecification of required exchange functions by identification ofexisting and planned inter-exchange signalling arrangementsSignalling philosophies and types of signallingSignalling system specifications (channel ass
28、ociated and commonchannel, as appropriate)Interworking of signalling systemsI. OperationThe specification of exchange features designed to facilitate theoperation of the exchange with respect to the administrations of:- subscribers- routing- traffic- tariffs and charging- recording and billing- syst
29、em controltaking into account remote control possibilitiesJ. MaintenanceThe specification, with respect to maintenance, of:- subscriber lines- inter-exchange circuits- switching network- control systemthe specification of testing and maintenance features, taking intoaccount the objectives of:- minim
30、ization of the fault rate- simplification of maintenance activities- adequate equipment repair facilities- maximization of immunity to failures- optimizing maintenance centralizationL. Input/output devices for operation and maintenanceGAS 2 V 3.2, 3.3GAS 6 VI 1.3.1GAS 3 II 3.1Recs. G.120-G.123GAS 2
31、V 6.2GAS 6 IV 8, VI 1.3.2Recs. E. 131Q.16, Q.23, Q.35 (E.180), Q.118Recs. I.412Q.512, Q.920, Q.921, Q.930, Q.931GAS 6 II 2, IV 8, VI 1.6GAS 3 II 3.2Recs. Q.7, Q.21Supplement No. 3 toSeries Q RecommendationsRecs. Q.101-Q.103, Q.105-Q.118 bis,Q.251-Q.300, Q.310-Q.331, Q.400-Q.490,Q.701-Q.795Recs. Q.60
32、1 -Q.685GAS 6 IV 7.4-7, 9.1-2VI 1.5.3-4, 1.9Recs. E.500Q.505, Q.506, Q.515, Q.516Z.331-Z.333GAS 6 IV 9.1, 9.3, VI 1.10Recs. G.231M.565O.22 (Q.49)Q.506, Q.516Z.301, Z.331-Z.333GAS 6 VI 1.11Recs. E.220, E.221Z.301-Z.302, Z.311-Z.317, Z.321-Z.323Fascicle VI.1 - Rec. Q.4 5TABLE 2/Q.4Titles of CCITT text
33、s (Recommendations and GAS Handbooks)relevant to national switching applicationsCCITT Manual Local telephone networks, ITU, Geneva, 1968 (Gas 2 Handbook).CCITT Manual Transmission planning of switched telephone networks, ITU, Geneva, 1976 (Gas 3 Handbook).CCITT Manual Economic and technical aspects
34、of the choice of telephone switching systems, ITU, Geneva, 1981(GAS 6 Handbook).CCITT Manual Economic and technical aspects of the transition from analogue to digital telecommunication networks,ITU, Geneva, 1984 (GAS 9 Handbook).CCITT Rec. E.130 Choice of the most useful and desirable supplementary
35、telephone services.CCITT Rec. E.131 Subscriber control procedures for supplementary services.CCITT Rec. E.132 Standardization of elements of control procedures for supplementary telephone services.CCITT Rec. E.151 Conference calls.CCITT Rec. E.160 Definitions relating to national and international n
36、umbering plans.CCITT Rec. E.161 Arrangement of figures, letters and symbols on rotary dials and pushbutton telephone sets.CCITT Rec. E.163 Numbering plan for the international telephone service.CCITT Rec. E.170 Overflow - alternative routing - rerouting - automatic repeat attempt.CCITT Rec. E.171 In
37、ternational routing plan.CCITT Rec. E.180 Characteristics of the dial tone, ringing tone, busy tone, congestion tone, special information toneand warning tone.CCITT Rec. E.181 Customer recognition of foreign tones.CCITT Rec. E.182 Application of tones and recorded announcements in telephone services
38、.CCITT Rec. E.211 Numbering and dialling procedures for VHF/UHF and maritime mobile satellite services.CCITT Rec. E.220 Ergonomic aspects of visual display terminals.CCITT Rec. E.221 Human interface to visual display terminals.CCITT Recs. E.230-E.232 Charging (determination of collection charges) in
39、 the international telephone service.CCITT Rec. E.500 Measurement and recording of traffic.CCITT Rec. E.521 Calculation of the number of circuits in a group carrying overflow traffic.CCITT Rec. E.543 Grades of service in analogue/digital international telephone exchanges.CCITT Rec. E.410, E.411, E.4
40、12 and E.413 Network management.CCITT Series E. Recommendations Supplement No. 1 List of possible supplementary telephone services which may beoffered to subscribers.CCITT Series E. Recommendations Supplement No. 2 Various tones used in national networks.6 Fascicle VI.1 - Rec. Q.4CCITT Recs. G.120-G
41、. 123 General characteristics of national systems forming part of international connections.CCITT Rec. G.121 Corrected reference equivalents (CREs) of national systems.CCITT Rec. G.122 Influence of national networks on stability and echo losses in national systems.CCITT Rec. G.123 Circuit noise in n
42、ational networks.CCITT Rec. G.231 (2) Use of standard components in transmission equipment.CCITT Rec. G.703 General aspects of interfaces.CCITT Rec. G.704 Functional characteristics of interfaces associated with network nodes.CCITT Rec. G.705 Characteristics required to terminate digital paths on a
43、digital exchange.CCITT Recs. G.731-G.739 Principal characteristics of primary multiplex equipment.CCITT Recs. G.741-G.746 Principal characteristics of second order multiplex equipments.CCITT Rec. G.811 Performance of clocks suitable for plesiochronous operation of international digital links.CCITT R
44、ec. G.822 Controlled slip rate objectives on an international digital connection.CCITT Rec. I.412 ISDN user-network interfaces-channel structures and access capabilities.CCITT Rec. M.565 Access point for international telephone circuits.CCITT Rec. O.22 Specification for the CCITT automatic transmiss
45、ion measuring and signalling testing equipmentATME No. 2.CCITT Rec. Q.7 Signalling systems to be used for international automatic and semi-automatic telephone workingCCITT Rec. Q.12 Overflow-alternative routing - rerouting - automatic repeat attempt.CCITT Rec. Q.14 Means to control the number of sat
46、ellite links in an international telephone connection.CCITT Rec. Q.15 Nominal mean power during the busy hour.CCITT Rec. Q.16 Maximum permissible value for the absolute power level of a signalling pulse.CCITT Rec. Q.21 Systems recommended for out-band signalling.CCITT Rec. Q.23 Technical features of
47、 push-button telephone sets.CCITT Rec. Q.24 Multi-frequency push-button signal reception.CCITT Rec. Q.33 Protection against the effects of faulty transmission on groups of circuits.CCITT Rec. Q.35 Characteristics of the dial tone, ringing tone, busy tone, congestion tone, special information toneand
48、 warning tone.CCITT Rec. Q.45 Transmission characteristics of an international exchange.CCITT Rec. Q.48 Demand assignment signalling systems.CCITT Rec. Q.49 Specification for the CCITT automatic transmission measuring and signalling testing equipmentATME No. 2.CCITT Recs. Q.101-Q.103, Q.105-Q.118 bi
49、s Clauses applicable to CCITT standard systems.Fascicle VI.1 - Rec. Q.4 7CCITT Rec. Q.103 Numbering used.CCITT Rec. Q.105 National (significant) number.CCITT Rec. Q.106 The sending-finished signalCCITT Rec. Q.107 Standard sending sequence of forward address information.CCITT Rec. Q.107 bis Analysis of forward address in formation for routing.CCITT Rec. Q.108 One-way or both-way operation of international circuits.CCITT Rec. Q.110 General aspects of the utilization of standardized CCITT signalling systems on PCM links.CCITT Rec. Q.115 Control of echo suppressors.CCITT Recs. Q.
