1、 AMERICAN NATIONAL STANDARD FOR TELECOMMUNICATIONS ATIS-1000632.1993(R2014) ISDN Supplementary Service Normal Call Transfer As a leading technology and solutions development organization, ATIS brings together the top global ICT companies to advance the industrys most-pressing business priorities. Th
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12、pretation of any American NationalStandard. Moreover, no person shall have the right or authority to issue aninterpretation of an American National Standard in the name of the AmericanNational Standards Institute. Requests for interpretations should be ad-dressed to the secretariat or sponsor whose
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14、erican National Standards mayreceive current information on all standards by calling or writing the AmericanNational Standards Institute.Published byAmerican National Standards Institute11 West 42nd Street, New York, New York 10036Copyright 1993 by Alliance for Telecommunications Industry SolutionsA
15、ll rights reserved.No part of this publication may be reproduced in anyform, in an electronic retrieval system or otherwise,without prior written permission of the publisher.Printed in the United States of AmericaAPS2.5C1293/30iContentsPageForeword .ii1 Purpose, scope, and application.12 Normative r
16、eferences13 Definitions .24 Description of Normal Call Transfer from the users perspective25 Functional capabilities and information flows for Normal Call Transfer 86 Switching and signaling specifications for the Normal Call Transfer service at the user/network interface 107 Switching and signaling
17、 specifications for the Normal Call Transfer at interexchange interfaces.188 Specifications for protocol interworking 22Tables1 Subscription options for Normal Call Transfer per Terminal Service Profile(TSP) or per ISDN Number/Bearer Service/TSP22 Normal Call Transfer service scenario13Figures1 Over
18、all SDL for Normal Call Transfer (CTN) service operation42 Functional entity model for the Normal Call Transfer service .83 Normal Call Transfer, primary call not already on hold.114 Normal Call Transfer, primary call already on hold.125 HOLD message content146 INFORMATION message (u - n) content157
19、 INFORMATION message (n - u) content158 Cause value159 Notification description1610 Normal Call Transfer invoked while a call is active.2011 Normal Call Transfer invoked before the call is active21iiForeword (This foreword is not part of American National Standard T1.632-1993.)This is one of a serie
20、s of standards on Integrated Services Digital Network(ISDN) supplementary services. This standard defines and describes theNormal Call Transfer service capabilities in the context of the ISDN. Thisstandard provides the switching and signaling specifications to allow aserved user to transfer one voic
21、eband information or 64kbit/s data call toanother voiceband information or 64kbit/s data call. The Normal CallTransfer service optionally allows the ISDN to notify the transferred partiesof the transfer, if the served user subscribes to this capability. This stan-dard includes the Digital Subscriber
22、 Signaling System No. 1 (DSS1) andthe Signaling System No. 7 ISDN User Part protocol and procedures tosupport these capabilities.Service providers of Call Transfer services will find this standard to be use-ful in providing a consistent suite of protocols and procedures to supportthe service capabil
23、ities described in this standard. Manufacturers of userand network equipment which use the Integrated Services Digital Network(ISDN) and Signaling System No. 7 can apply this standard to the designand development of their products.This standard was developed by Working Groups T1S1.1, T1S1.2, andT1S1
24、.3 of Accredited Standards Committee T1 Telecommunications. Suggestions for improvement of this standard will be welcome. Theyshould be sent to the Alliance for Telecommunications Industry Solutions,T1 Secretariat, 1200 G Street, NW, Suite 500, Washington, DC, 20005.This standard was processed and a
25、pproved for submittal to ANSI byAccredited Standards Committee T1 Telecommunications. Committeeapproval of the standard does not imply that all committee members votedfor its approval. At the time it approved this standard, AccreditedStandards Committee T1 had the following members:A. K. Reilly, Cha
26、irmanG. H. Peterson, Vice-ChairmanO. J. Gusella, SecretaryE. R. Hapeman, Senior EditorSelvam Rengasami, Technical EditorOrganization Represented Name of RepresentativeEXCHANGE CARRIERSAmeritech Services, Inc. Laurence A. YoungJames Orme (Alt.)Bell Atlantic.John W. SeazholtzRoger Nucho (Alt.)Bellcore
27、.James C. StaatsE. R. Hapeman (Alt.)BellSouth Telecommunications, Inc. Leonard Strickland, Jr.William J. McNamara, III (Alt.)Centel Corporation Bruce BeckerCincinnati Bell Telephone Kevin R. SullivanScott M. Kalinoski (Alt.)Exchange Carriers Standards AssociationGregory L. TheusJames L. Eitel (Alt.)
28、GTE Telephone Operations .Gregory L. TheusRichard L. Cochran (Alt.)National Telephone Cooperative Association .Joseph M. FlaniganNYNEX .James F. BaskinJim Papadopoulos (Alt.)iiiPacific Bell Sal R. TesoroPuerto Rico Telephone Company.Segundo RuizAlberto E. Morales (Alt.)Southwestern Bell Corporation
29、Joseph MendozaC. C. Bailey (Alt.)Sprint Local Telecommunications Division.Robert P. McCabeHarold L. Fuller (Alt.)US Telephone Association (USTA) Dennis ByrnePaul Hart (Alt.)US WestJames L. EitelJames Dahl (Alt.)INTEREXCHANGE CARRIERSAmerican Mobile Satellite Corporation .Michael K. WardWilliam Garne
30、r (Alt.)ATb) In response to the second Normal CallTransfer request;c) After the first Normal Call Transferrequest is accepted, but before the secondNormal Call Transfer request;d) When certain conditions prevent theoptional notification from being delivered tothe transferred user.4.2.3.2.1 First Nor
31、mal Call Transfer re-questThe first Normal Call Transfer service requestshall be rejected by the network if any of thefollowing conditions occur:a) The user invoking the service has notsubscribed to the Normal Call Transfer ser-vice;b) The A B call cannot be placed on hold;c) The invocation of the t
32、ransfer servicewould be in conflict with some other servicethat is in process or is active.If any of the conditions above occur, then thenetwork shall notify the served user of the rejec-tion and shall take no action on the A B call.4.2.3.2.2 Second Normal Call Transfer re-questThe second Normal Cal
33、l Transfer servicerequest shall be rejected by the network if anyof the following conditions occur:a) The Secondary Call (to User C) was notestablished, or the call had not reached thealerting state;b) The call transfer would violate someother service interaction;c) Both the A B call and A C calls a
34、realerting;d) Either User B or User C is in the processof clearing its call with the served user;e) The network cannot connect Users Band C due to incompatible bearer servicesfor the A B and A C calls. “Speech” and“3.1 kHz Audio” shall not be considered asbeing incompatible.The network shall notify
35、the served user of therejection and shall take no action on the A Band A C calls. The Normal Call Transfer ser-vice request shall be aborted.3ANSI T1.632-19934NOTE In every state except “B C Active, CTN Idle” there may also be an A C call established.Figure 1 (Part 1 of 3): Overall SDL for Normal Ca
36、ll Transfer (CTN) service operationANSI T1.632-19935Figure 1 (Part 2 of 3): Overall SDL for Normal Call Transfer (CTN) service operationANSI T1.632-19936Figure 1 (Part 3 of 3): Overall SDL for Normal Call Transfer (CTN) service operationANSI T1.632-19934.2.3.2.3 OtherThe Normal Call Transfer service
37、 requestshall be aborted if any of the following eventsoccur after the first Normal Call Transferrequest is accepted by the network but beforethe second Normal Call Transfer servicerequest is made by the served user:a) The A B call is cleared by either UserA or User B;b) The A B call is retrieved by
38、 User A;c) Another service interaction overridesthe Normal Call Transfer service.If any of the events above occur, then the net-work shall send an indication to the serveduser that the Normal Call Transfer servicerequest has been aborted.4.2.3.2.4 Optional notification of transferWhen notification i
39、s to be delivered to a trans-ferred user, certain conditions may preventthe transferred user from receiving or accept-ing the notification information. The notifica-tion information may not be delivered to thetransferred user. Some examples of when thenotification would not be received or acceptedby
40、 the transferred user are provided below.a) The call with User A is cleared fromUser Bs perspective before User Breceives the notification information;b) There is interworking with a non-ISDNnetwork between User A and User B.4.2.4 Alternative proceduresNone identified.4.3 Interworking considerations
41、When interworking occurs on both primaryand secondary calls to be transferred andwhere both calls were originated by theserved user, restrictions should be placed onthe ability of the served user to complete thetransfer operation. This is required to preventthe unsupervised connection of two non-ISD
42、Nparties who may be served from exchangesthat do not immediately forward disconnect foran incoming call.The ISDN network shall not allow the serveduser to complete the transfer, and shall notdisconnect the served user from the call,unless the primary or secondary call is one ofthe following:a) an of
43、f-hook non-ISDN line;b) an answered ISDN call on an accessserved by the controlling switch;c) an incoming trunk served by the con-trolling switch;d) an outgoing trunk in the answered statethat did not encounter interworking.If User B, User C, or both are not ISDN termi-nals, are not connected to an
44、ISDN, or there isinterworking with a non-ISDN between theserved user and network B or network C, then itmay not be possible to deliver to User B and/orUser C the optional notification of a transfer.4.4 Interactions with other supplementaryservices4.4.1 Call WaitingAn incoming waiting call to the ser
45、ved usershall not be transferred; it must first beanswered.4.4.2 Normal Call TransferIt may be possible for both users (User A andUser B) in a basic call, who have both sub-scribed to the Normal Call Transfer service, tosimultaneously transfer the call. That is, User Atransfers the call to User C an
46、d User B trans-fers the call to User D. Call progress signalsand other notifications shall be delivered to theappropriate party when the signal is received.The result of these simultaneous transfers isthat User C is connected to User D.Simultaneous transfers affect the delivery ofthe notifications o
47、f the transfers. For example,when User A transfers User B to a User C, anoptional notification of the transfer may besent toward User B. Depending on the state ofUser Bs attempt to transfer User A, the notifi-cation is delivered:a) to User B if the A B call reference isstill active, i.e., User B has
48、 not completedtransfer so the call reference for the A Bcall is still active;b) to User D (the party to which User Btransferred User A) if the call reference hasbeen cleared by User Bs service provider,i.e., if User Bs transfer completed first,7tion between the functional units (called “enti-ties”)
49、using information flows, which are alsoidentified in this clause. An information flow isan abstraction that is subsequently realized inclauses 6 through 8 by means of additions toexisting signaling system messages or by newmessages. Finally, this clause identifies sev-eral ways in which the functional entities ofthe Normal Call Transfer service can be locat-ed in specific network or user equipment.5.1 Functional entity model for the NormalCall Transfer serviceThis subclause identifies a way of partitioningthe Normal Call Transfer service functionalityinto functional
