1、INTERNATIONAL TELECOMMUNICATION UNION)45G134 5 TELECOMMUNICATIONSTANDARDIZATION SECTOROF ITU4%,%2!0(G0G037)4#().2!$)/4%,%8G0G0).4%27/2+).%.%2!,G0G02%15)2%-%.43G0G04/G0G0“%G0G0-%4).G0G0).4%2 amended at Malaga-Torremolinos, 1984)The CCITTconsidering(a) that, with fully automatic working between subscr
2、ibers in the international telex service, it is desirablethat the interface between the international telex network and maritime satellite systems be defined;(b) that the CCIR is charged with the task of making Recommendations relating to the radio path ofmaritime satellite systems;(c) that explanat
3、ion of the detail of the interface between the international telex network and maritimesatellite systems would be of assistance to the CCIR;(d) that Recommendation U.61 specifies the detailed interface requirements,unanimously recommends(1) that maritime satellite systems should be capable of interf
4、acing the international telex network with oneor more signalling systems in accordance with: Recommendation U.1: Signalling conditions to be applied in the international telex service (type A andtype B signalling); Recommendation U.11: Telex and gentex signalling on intercontinental circuits used fo
5、r intercontinentalautomatic transit traffic (type C signalling); Recommendation U.12: Terminal and transit control signalling system for telex and similar services oninternational circuits (type D signalling);(2) that type D signalling (Recommendation U.12) and, as a second choice, type C signalling
6、(Recommendation U.11) are the preferred signalling systems, when they are available within the national boundaries,for the reasons given in Annex A;(3) that as the maritime signalling from the ship to the coast earth station is in the same relationship as theconnection from the subscriber to the ori
7、ginating exchange in the international network, it is necessary that the transitdelays inherent in the maritime system should be considered in conjunction with the standards recommended for theinternational network;(4) that the access of ship earth stations to store-and-forward units, if provided, s
8、hould be in accordancewith the relevant Series F and U Recommendations on international store-and-forward units.2 Fascicle VII.2 - Rec. U.60ANNEX A(to Recommendation U.60)Signalling systems types C and DA.1 These signalling systems have been developed in CCITT to permit the maximum utilization of th
9、einternational telex network as well as to simplify the interface problems that exist between Administrations usingdifferent signalling systems within their national boundaries. In particular, types C and D signalling systems, which usetelex destination codes in accordance with Recommendation F.69 1
10、, are of assistance in solving the problems ofrouting to and from maritime satellite systems where multiple access techniques are employed.A.2 Type C signalling (Recommendation U.11) facilitates the use of improved techniques for switching traffic inthe international network. In particular:(a) it pe
11、rmits any telegraph circuit capable of carrying International Telegraph Alphabet No. 2 (ITA 2) to beused without the need to convert supervisory signals to a form capable of being carried by the circuit;(b) it permits the automatic testing of the ability of the international circuit to transmit tele
12、printer charactersbefore the call is established to the distance subscriber;(c) it permits the detection of head-on collision of calls and thus permits service protocols to be establishedin handling such collisions. It may be noted that head-on collisions may occur on telegraph circuits thatare oper
13、ated in the bothway mode due to the fact that the calling signal takes a finite time, dependingupon the nature of the transmission path, before the receiving end of the circuit detects the seizure fromthe outgoing end;(d) it permits the efficient use of the international network with particular refe
14、rence to the most economicaluse of automatic alternative routing and, by providing transit centre identification, permits full flexibilityin routing as well as international accounting and subscriber billing.A.3 Type D signalling (Recommendation U.12) facilitates the introduction into the internatio
15、nal network of thefollowing facilities (in addition to the advantages mentioned in A.2 above):(a) user groups;(b) network identification signals;(c) identification of the calling station without the necessity of using the WRU signal;(d) identification of a call relating to service matters, which the international network carries as a non-chargeable call.Reference1 CCITT Recommendation Plan for telex destination codes, Rec. F.69.
