1、INTERNATIONAL TELECOMMUNICATION UNION)45G134 ) TELECOMMUNICATIONSTANDARDIZATION SECTOROF ITU).4%2!4%$G0G03%26)#%3G0G0$)4!,G0G0.%47/2+G0 )3$.G93%26)#%G0G0#!0!“),)4)%34%,%3%26)#%3G0G03500/24%$G0G0“9G0G0!.G0G0)3$. 4%,%8)45G134G0G0RecommendationG0G0) (Extract from the “LUEG0“OOK)NOTES1 ITU-T Recommendat
2、ion I.241.6 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 slightly different from the Blue Book version, thecontents of the file are identical to the Blue Book version and copyright conditions remai
3、n 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 rights reserved. No part of this publication may be reproduced or utilized in any form or
4、by any means, electronic ormechanical, including photocopying and microfilm, without permission in writing from the ITU.Fascicle III.7 - Rec. I.241.6 1Recommendation I.241.6Fascicle III.7 - Rec. I.241.6TELESERVICES SUPPORTED BY AN ISDN: TELEX(Melbourne, 1988)6 Telex6.1 DefinitionThis service provide
5、s interactive text communication. The digital signal at the S/T reference point follows theinternationally agreed Recommendations for telex above the ISDN physical layer.6.2 DescriptionFor further study.6.3 ProceduresFor further study.6.4 Network capabilities for chargingThis Recommendation does not
6、 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.6.5 Interworking requirementsFor further study.6.6 Interaction with supplementary servicesFor further study.6.7 Attribut
7、es and values of attributes of the telex servicea) LOW LAYER ATTRIBUTESInformation transfer attributes1. Information transfer mode: circuit (packet is for further study (Note)2. Information transfer rate: 64 kbit/s3. Information transfer capability: unrestricted4. Structure: 8 kHz integrity5. Establ
8、ishment of communication: reserved/permanent6. Symmetry: bidirectional7. Communication configuration: point-to-pointAccess attributes8. Access channel: B for user informationD for signalling(D for telex user information is for further study (Note)9. Access protocol:9.1 Signalling access protocol lay
9、er 1: I.430/I.4319.2 Signalling access protocol layer 2: U.2029.3 Signalling access protocol layer 3: U.2029.4 Information access protocol layer 1: I.430/I.4319.5 Information access protocol layer 2: U.2029.6 Information access protocol layer 3: for further study2 Fascicle III.7 - Rec. I.241.6b) HIG
10、H LAYER ATTRIBUTES10. Type of user information: telex11. Layer 4 protocol functions 12. Layer 5 protocol functions 13. Layer 6 protocol functions For further study14. Layer 7 protocol functions c) GENERAL ATTRIBUTES15. Supplementary services provided: for further study16. Quality of Service: for fur
11、ther study17. Interworking possibilities: Telex, Teletex (others: for further study)18. Operational and commercial: for further studyNote - Subject to satisfying telex quality of service on D-channel.6.8 Recommended support of Telex by an ISDNa) Overall support1: FSb) Variations of non-dominant attr
12、ibutes:1) Information transfer mode circuit: FS packet: FS2) Establishment Symmetry Communication Support1of communication configuration_demand pt-pt Ereserved bidirectional pt-pt FSpermanent symmetric pt-pt Ademand multipt Areserved bidirectional multipt FSpermanent symmetric multipt A1The definiti
13、on of E (essential) and A (additional) can be found in Recommendation I.240.Fascicle III.7 - Rec. I.241.6 33) AccessSignalling and OAM(Note 1)User informationSupportChannel and rate Protocols Channel and rate ProtocolsCircuit modeD(16) I.430, I.440, I.441,I.450, I.451(Note 2)B(64) I.430, U.202(Note
14、3)FSD(64) I.431, I.440, I.441,I.450, I.451(Note 2)B(64) I.431, U.202(Note 3)FSPacket modeD(16) FS (Note 4) D(16) FS FSNote 1 - Definition of protocols for OAM is for further study.Note 2 - Layer 2 and 3 protocols are for further study.Note 3 - Others are for further study.Note 4 - Subject to satisfying telex quality of service on D-channel.6.9 Dynamic descriptionFor further study.
