1、INTERNATIONAL TELECOMMUNICATION UNION)45G134 ) TELECOMMUNICATIONSTANDARDIZATION SECTOROF ITU).4%2!4%$G0G03%26)#%3G0G0$)4!,G0G0.%47/2+G0 )3$.G93%26)#%G0G0#!0!“),)4)%3G0 G0“%!2%2G0G03%26)#%33500/24%$G0G0“9G0G0!.G0G0)3$.#)2#5)4G13-/$%G0G0“%!2%2G0G03%26)#%#!4%/2)%3G0G0 G0G0#)2#5)4G13-/$% G0G0!,4%2.!4%30
2、%#(G0 G0 G0KBIT SG0G05.2%342)#4%$ G0K(ZG0G03425#452%$G0G0“%!2%2G0G03%26)#%)45G134G0G0RecommendationG0G0) (Extract from the “LUEG0“OOK)NOTES1 ITU-T Recommendation I.231.4 was published in Fascicle III.7 of the Blue Book. This file is an extract fromthe Blue Book. While the presentation and layout of
3、the text might be slightly different from the Blue Book version, thecontents 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
4、administration and a recognized operating agency. ITU 1988, 1993All 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 III.7 - Rec.
5、I.231.4 1Recommendation I.231.4Fascicle III.7 - Rec. I.231.4CIRCUIT-MODE BEARER SERVICE CATEGORIES CIRCUIT-MODE, ALTERNATE SPEECH / 64 kbit/sUNRESTRICTED, 8 kHz STRUCTURED BEARER SERVICE(Melbourne, 1988)4 I.231.4 - Circuit-mode, alternate speech / 64 kbit/s unrestricted, 8 kHz structured bearer serv
6、icecategory4.1 DefinitionThis bearer service category provides the alternate transfer of speech or 64 kbit/s unrestricted digitalinformation within the same call.The request for this alternate capability and the initial mode desired by the user must be identified at call set-up time.This bearer serv
7、ice category is provided for the support of multiple capability terminals or single capabilityterminals (Note 1).For the speech mode of this bearer service category, the same applies as for the speech bearer servicecategory. For the unrestricted mode of this bearer service category, the same applies
8、 as for the unrestricted (Note 2)bearer service category.Note 1 - Initially, this service will only be applicable to multiple capability terminals. The use of this serviceby, and the network support of, single capability terminals is for further study, (e.g. how does a user change terminals).All ref
9、erences to single capability terminals reflect possible future enhancements and are subject to change and haveonly been included for information.Note 2 - During an interim period some networks may only support restricted 64 kbit/s digital informationtransfer capability, i.e. information transfer cap
10、ability solely restricted by the requirement that the all-zero octet is notallowed. For interworking, the rules given in the Appendix I of Recommendation I.520 should apply. The interworkingfunctions have to be provided in the network with restricted capability. The ISDN with 64 kbit/s transfer capa
11、bilitieswill not be affected by this interworking, other than by conveying the appropriate signalling message to or from theISDN terminal.4.2. Description4.2.1 General descriptionOnce the connection is established, the user may repeatedly request via appropriate signalling messages, toalternate from
12、 speech mode to 64 kbit/s unrestricted digital mode, or vice versa. The in-call modification shall beprovided on a per call basis.4.2.2 Specific terminologyNone identified.4.2.3 Qualifications on the applicability to telecommunications servicesNone identified.4.3 Procedures4.3.1 Provision/withdrawal
13、This service shall be provided by prearrangement with the Administration.2 Fascicle III.7 - Rec. I.231.44.3.2 Normal procedures4.3.2.1 Activation/deactivation/registrationNot applicable.4.3.2.2 Invocation and operationAt the start of the call the request for an alternate speech/64 kbit/s unrestricte
14、d call and the initial mode ofeither speech or 64 kbit/s unrestricted call must be identified. Following call set-up, the calling or called party maychoose to modify the characteristics of the call during the conversation/data phase. During call establishment, thenetwork shall choose a suitable rout
15、e according to the information included in the set-up message.Depending on the terminal capability type the following procedures will apply:a) For multiple capability terminals the requesting user will send an invoke in-call modification request tothe network.b) For single capability terminals the r
16、equesting user will change over the connection from the first terminalto the second terminal before sending an invoke in-call modification request to the network.The network will, on receipt of the in-call modification request from the calling/called party, check if that callmodification is allowed
17、and if the necessary resources are available.If acceptable, the resources are reserved and an invoke in-call modification request is sent to the distant end. Atimer will be started to supervise that the in-call modification is received successfully.Depending on the terminal configuration at the dest
18、ination end, the procedures will be the following:a) For multiple capability terminals the distant user, if agreeing with the service changeover, will transmit areturn result indication while the resources in the network are switched in, if reserved previously and thecall modification indication wil
19、l be sent to the initiating party.b) For single capability terminals a call changeover will be performed from the first terminal to the secondterminal. An in-call modification return result will be sent to the network which will switch in theresources, if reserved previously.4.3.3 Exceptional proced
20、ures4.3.3.1 Activation/deactivation/registrationNot applicable.4.3.3.2 Invocation and operationIf the network fails to change resources on receipt of the in-call modification return result, the connection willbe cleared with a cause indication “temporary failure“.If on receipt of a call modification
21、 invocation request an exchange determines that in-call modification is notallowed or not possible a call modification return error indication will be sent. Receipt of the call modification returnerror indication will cause the reserved resources to be freed and a call modification return error indi
22、cation to bedelivered to the initiating party.In case of in-call modification failure, the initiating terminal after having received the in-call modificationreturn error indication, will resume to transmit and receive the bit stream for the previous service.4.3.4 Alternative proceduresNone identifie
23、d.Fascicle III.7 - Rec. I.231.4 34.4 Network capabilities for chargingThis Recommendation does not cover charging principles. Future Recommendations in the D-Series areexpected to contain that information.It shall be possible to charge the subscriber accurately for the service.4.5 Interworking requi
24、rementsFor further study.4.6 Interactions with supplementary servicesFor further study.4.7 Attributes and values of attributes of the circuit-mode, alternate speech / 64 kbit/s unrestricted, 8 kHzstructured bearer service categoryInformation transfer attributes1. Information transfer mode: circuit2.
25、 Information transfer rate: 64 kbit/s3. Information transfer capability: alternately speech (Note 1) or unrestricted digital information4. Structure: 8 kHz integrity5. Establishment of communication: demand/reserved/permanent6. Symmetry: bidirectional symmetric/unidirectional7. Communication configu
26、ration: point-to-point/multipointAccess attributes8. Access channel: B for user information,D for signalling (Note 2)9. Access protocol: I-Series for D-channelGeneral attributes10. Supplementary services provided 11. Quality of Service (Note 3) for further study12. Interworking possibilities 13. Ope
27、ration and commercial aspects Note 1 - When crossing an international boundary between Administrations which employ different encodinglaws, the network shall perform the necessary A- law conversion (see Recommendation G.711).Note 2 - For reserved/permanent service the operational, administrative and
28、 maintenance (OAM) messagesrelated to these services may be conveyed over the D-channel.Note 3 - A short service changeover time (with a high probability of not being exceeded) has been tentativelyidentified as a requirement.4 Fascicle III.7 - Rec. I.231.44.8 Provision of individual circuit mode, al
29、ternate speech/64 kbit/s unrestricted, 8 kHz structured bearer servicesa) Overall provision1): ANote - Some networks will offer the speech phase of these services in a manner identical to the 3.1 kHzaudio service.b) Variations of secondary attributes:Establishment Symmetry Communication Provision1)o
30、f communication of configurationI.231.4/1 demand pt-pt EI.231.4/2 reserved pt-pt AI.231.4/3 permanent pt-pt E bidirectionalI.231.4/4 demand multipt AI.231.4/5 reserved multipt AI.231.4/6 permanent multipt Ac) AccessSignalling and OAM (Note 1) User information ProvisionChannel rate Protocols Channel
31、and rate ProtocolsD(16)D(64)I.451 (Note 2)I.451 (Note 2)B(64)B(64)G.711/user-definedG.711/user-definedEENote 1 - Definition of protocols for OAM is for further study.Note 2 - Demand services only; further study for reserved and permanent services. The protocols for initiating the changeoverbetween s
32、peech and unrestricted digital information, and synchronizing this changeover are for further study.4.9 Dynamic descriptionThe dynamic description for this service needs further study and is not yet available._1)The definition of E (essential) and A (additional) can be found in Recommendation I.230.
