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2、!293%26)#%3)45G134G0G0RecommendationG0G01 (Extract from the “LUEG0“OOK)NOTES1 ITU-T Recommendation Q.80 was published in Fascicle VI.1 of the Blue Book. This file is an extract from theBlue Book. While the presentation and layout of the text might be slightly different from the Blue Book version, th
3、econtents of the file are identical to the Blue Book version and copyright conditions remain unchanged (see below).2 In this Recommendation, the expression “Administration” is used for conciseness to indicate both atelecommunication administration and a recognized operating agency. ITU 1988, 1993All
4、 rights reserved. No part of this publication may be reproduced or utilized in any form or by any means, electronic ormechanical, including photocopying and microfilm, without permission in writing from the ITU.Fascicle VI.1 - Rec. Q.80 1Recommendation Q.80Fascicle VI.1 - Rec. Q.80INTRODUCTION TO ST
5、AGE 2 SERVICE DESCRIPTIONSFOR SUPPLEMENTARY SERVICES1 IntroductionThe purpose of this Recommendation is to provide an introduction to the Stage 2 service descriptions forsupplementary services, given in Recommendations Q.81-87.2 Cross-referencesThe work in Recommendations Q.81-87 is based on the Sta
6、ge 1 service descriptions given in the I.251-257-Series Recommendations (see Annex A). They are coordinated with the Stage 2 service description for basic calls, givenin Recommendation Q.71, and were developed according to the methodology given in Recommendation Q.65.3 Relationships among supplement
7、ary services3.1 Call diversion servicesRecommendation I.252, 2-5, defines a set of supplementary services called “Call Diversion Services“. Thisset consists of the Call Forwarding supplementary services and the Call Deflection supplementary service. This sectiondescribes how these services relate to
8、 each other and describes the different network routing techniques which may beused to provide these services. It begins with the latter topic.3.1.1 Network Routing TechniquesFigure 1/Q.80 gives an overview of the Call Diversion services and illustrates the network routing techniquesthat may be used
9、 for these services.Referring to Figure 1/Q.80, a Call Diversion occurs if User A calls User B who has subscribed to one of theCall Diversion services, and the call processing for that service (described below) determines that the call should be sentto User C.If User C is relatively close to User B,
10、 then it would be reasonable for User Bs serving switch to simply switchthe call to User C (i.e. act like a transit switch as if User A had called User C directly). This technique is called “forwardswitching“.If User C is not close to User B (e.g. User CC in Figure 1/Q.80), then it might be reasonab
11、le for User Bsserving switch to ask that a previous switch in the call path (e.g. Switch 2) to re-route the call. This is called “(partial)rerouting“. If User Bs serving switch asks that User As switch (i.e. Switch 1) re-route the call, this is called “(full)rerouting“.Note 1 - The choice of network
12、 routing technique is the prerogative of each network provider and may bedetermined by factors other that geographical distance.Note 2 - The analogy to a transit switch is not totally correct. In general, User A will be charged for theconnection to User B, and User B will be charged for the connecti
13、on to User C.2 Fascicle VI.1 - Rec. Q.803.1.2 Call processingIn Call Forwarding, the decision to divert the call is made by the serving switch, either because it has beeninstructed (by a previous interaction with the served user) to forward all calls, or to forward any calls that meet busy, orthose
14、that meet No Reply. (See Figure 2/Q.80). (Details of the call processing for Call Forwarding are given inRecommendations Q.82, 2, 3 and 4).In Call Deflection, the decision to divert the call is made by the served user, upon receipt of an incoming callindication. (Note - Care should be taken not to c
15、onfuse Call Deflection with a possible architecture for Call Forwardingwhich places the “forwarding detection“ entity in the served users equipment. In Call Deflection, the actual user isinvolved in deciding whether to divert the call). (Details of the call processing for Call Diversion are expected
16、 to beprovided early in the next study period.)Fascicle VI.1 - Rec. Q.80 3ANNEX A(to Recommendation Q.80)Cross-reference list of Stage 1 and Stage 2Recommendations on supplementary services1)Stage 2 Based on Stage 1 given in:Q.80 Introduction to Stage 2 service description for supplementary services
17、Q.81 Number identification supplementary services I.251 1 Direct dialling in I.251, 1( 2) Multiple subscriber number I.251, 2 3 CLIP I.251, 3 4 CLIR I.251, 4 5 COLP I.251, 5 6 COLR I.251, 6( 7) Malicious call ID (I.251, 7)( 8) Sub-addressing (I.251, 8)_1)Parentheses “( )“ around a of a Recommendatio
18、n number implies that the may not appear in the 1988CCITT Recommendations.4 Fascicle VI.1 - Rec. Q.80Stage 2 Based on Stage 1 given in:Q.82 Call offering supplementary services I.252( 1) Call transfer I.252, 1 2 Call forwarding busy I.252, 2 2 Call forwarding no reply I.252, 3 2 Call forwarding unco
19、nditional I.252, 4( 3) Call deflection (I.252, 5) 4 Line hunting I.252, 6Q.83 Call completion supplementary services I.253 1 Call waiting I.253, 1 2 Call hold I.253, 2( 3) CCBS (I.253, 3)(Q.84) Multiparty supplementary services I.254( 1) Conference calling I.254, 1( 2) Three-party I.254, 2Q.85 “Comm
20、unity of interest“ supplementary services I.255 1 Closed user group I.255, 1( 2) ISDN networking services (I.255, 2)Private numbering planQ.86 Charging supplementary services I.256 1 Credit card calling I.256, 1 2 Advice of charge I.256, 2( 3) Reverse charging (I.256, 3)Q.87 Additional information transfer supplementary services I.257 1 User-to-user signalling I.257, 1
