1、INTERNATIONAL TELECOMMUNICATION UNION)45G134 1 TELECOMMUNICATIONSTANDARDIZATION SECTOROF ITU%.%2!,G0G02%#/-%.$!4)/.3G0G0/.G0G04%,%0(/.%37)4#().G0G0!.$G0G03).!,).).4%2.!4)/.!,G0G0!54/-!4)#G0G0!.$3%-)G13!54/-!4)#G0G07/2+).-%!.3G0G04/G0G0#/.42/,G0G04(%G0G0.5-“%2G0G0/&3!4%,)4%G0G0,).+3G0G0).G0G0!.G0G0).
2、4%2.!4)/.!,4%,%0(/.%G0G0#/%#4)/.)45G134G0G0RecommendationG0G01 (Extract from the “LUEG0“OOK)NOTES1 ITU-T Recommendation Q.14 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
3、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 recognized operating agen
4、cy. 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 VI.1 - Rec. Q.14 1Recommendation Q.14Fascicle VI.1 - Rec. Q
5、.14MEANS TO CONTROL THE NUMBER OF SATELLITE LINKS IN ANINTERNATIONAL TELEPHONE CONNECTIONRecommendation Q.41 states that connections with a mean one-way propagation time in excess of 400 msshould be avoided apart from exceptional circumstances. Means should therefore be provided in international swi
6、tchingcentres to prevent the multiple connection of satellite links whenever possible.The following principles should apply in controlling such connections:a) If an exchange can determine the prior connection of a satellite link in a connection by:- information relating to the incoming circuit,- rec
7、eipt of the Nature of Circuit Indicator: “satellite included“,the exchange should forward the call on a terrestrial circuit. A satellite circuit may be used in thefollowing exceptional circumstances:- where no terrestrial circuits are provided to the required destination,- where only a few terrestri
8、al circuits are provided on a final route and the loss of quality of service ofa double satellite connection (echo problems and “double-talk“) is preferable to the degradation ofgrade of service that would be caused by the exclusion of the satellite circuits.A Nature of Circuit Indicator “satellite
9、included“ should be forwarded on the outgoing circuit wherepossible.b) If an exchange can determine by an analysis of the call destination that a satellite link will definitely ormost probably be included at a later point in the call connection, it should give priority to terrestrial linksin its out
10、going circuit selection. Special attention is drawn to the analysis of country code 87S which mayindicate that the call will include a maritime satellite link. (For the use of the S digit, seeRecommendations E.210 1 and E.211 2.).The above principles apply to all international exchanges and to all n
11、ational exchanges which may connect tocircuits via domestic satellite systems.References1 CCITT Recommendation Ship station identification for VHF/UHF and maritime mobile-satellite services,Vol. II, Rec. E.210.2 CCITT Recommendation Selection procedures for VHF/UHF maritime mobile services, Vol. II, Rec. E.211.2 Fascicle VI.1 - Rec. Q.14
