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-/$%G0 G0G0 G0KBIT S
2、5.2%342)#4%$ G0G0 G0K(ZG0G03425#452%$“%!2%2G0G03%26)#%)45G134G0G0RecommendationG0G0) (Extract from the “LUEG0“OOK)NOTES1 ITU-T Recommendation I.231.5 was published in Fascicle III.7 of the Blue Book. This file is an extract fromthe Blue Book. While the presentation and layout of the text might be sl
3、ightly 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 administration and a
4、 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. I.231.5 1Recommendat
5、ion I.231.5Fascicle III.7 - Rec. I.231.5CIRCUIT-MODE BEARER SERVICE CATEGORIES CIRCUIT-MODE 2 64 kbit/sUNRESTRICTED,8 kHz STRUCTURED BEARER SERVICE(Melbourne, 1988)5 I.231.5 - Circuit-mode 2 64 kbit/s unrestricted, 8 kHz structured bearer service category5.1 DefinitionThis bearer service category pr
6、ovides the unrestricted transfer of two 64 kbit/s user information flows overtwoB-channels at the user network interface.5.2 DescriptionFor further study.5.3 ProceduresFor further study.5.4 Network capabilities for chargingThis Recommendation does not cover charging principles. Future Recommendation
7、s in the D-Series areexpected to contain that information.It shall be possible to charge the subscriber accurately for the service.5.5 Interworking requirementsFor further study.5.6 Interaction with supplementary servicesFor further study.5.7 Attributes and values of attributes of the circuit mode 2
8、 64 kbit/s unrestricted, 8 kHz structured bearerservice categoryInformation transfer attributes1. Information transfer mode: circuit2. Information transfer rate: 2 64 kbit/s3. Information transfer capability: unrestricted (Note)4. Structure: 8 kHz integrity with restricted differential time delay (R
9、DTD)5. Establishment of communication: demand/reserved/permanent6. Symmetry: bidirectional symmetric/bidirectional asymmetric/unidirectional7. Communication configuration: point-to-point/multipointAccess attributes8. Access channel: two B(64) for user information9. Access protocol: I-Series for D-ch
10、annel2 Fascicle III.7 - Rec. I.231.5General attributes10. Supplementary services provided 11. Quality of Service for further study12. Interworking possibilities 13. Operation and commercial aspects Note - Digit sequence integrity (DSI) is ensured for each elementary 64 kbit/s information.5.8 Provisi
11、on for individual circuit-mode 2 64 kbit/s, unrestricted, 8 kHz structured bearer servicesa) Overall provision1): Ab) Variations of secondary attributesEstablishment Symmetry Communication Provision1)of communication of configurationI.231.5/1 demand pt-pt EI.231.5/2 reserved bidirectional pt-pt AI.2
12、31.5/3 permanent pt-pt EOther combinations Ac) AccessSignalling and OAM (Note 1) User information ProvisionChannel rate Protocols Channel and rate ProtocolsD(16)D(64)I.451 (Note 2)I.451 (Note 2)2 B(64)2 B(64)User-definedUser-definedEENote 1 - Definition of protocols for OAM is for further study.Note 2 - Demand services only. Further study for reserved and permanent services.5.9 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.
