1、INTERNATIONAL TELECOMMUNICATION UNION)45G134 2 G0BISTELECOMMUNICATIONSTANDARDIZATION SECTOROF ITU4%,%2!0(94%,%2!0(G0G042!.3-)33)/.,)-)43G0G0/.G0G03).!,G0G042!.3(b) the need to divide the responsibility between Administrations involved in establishing internationalswitching connections;(c) that there
2、 are difficulties in specifying standard limits on transfer delay in a single telegraph channel onaccount of the variation in length and numbers of telephone channels connected in tandem on the bearer circuit;(d) that the use of satellite communication links in the international telegraph, telex and
3、 gentex networks andthe Maritime Mobile Service is increasing;(e) that the increase in the signal transfer delay caused by the conditions mentioned above requires thespecification of tolerable limits on signal transfer delay in the hypothetical reference connection;(f) that the transfer delays on si
4、gnalling elements inherent in the signalling types specified in the Series URecommendations will be considerable on multiple tandem sections;(g) the provision for hypothetical reference connections contained in Recommendation U.8,unanimously declares the view that1 When planning international connec
5、tions on the 50-baud telegraph, telex and gentex networks, the overallmaximum transfer delay should, in general, not exceed 4 seconds in the call setting-up phase and two seconds in theestablished phase of a call. The difference of both values should not exceed 950 ms for connections in which theter
6、minating exchange automatically returns the answerback.Note 1 In the maritime mobile service, the maximum transfer delay will be exceeded due to the delays in themaritime mobile satellite system which can be expected to be approximately 2170 ms from the maritime terminal to theshore station in the c
7、all established phase. In the call setting-up phase, this delay is approximately 4500 ms.Note 2 This limit is not applicable to the case of the interconnection of existing networks which use codeconversion facilities.Note 3 Because the main component of the transfer delay is in the maritime satellit
8、e link, then the differencein transfer delay between the call-connected signal and the answerback can be held within the permissible limits at theMaritime Satellite Switching Centre.2 When setting up connections in the 50-baud telegraph, telex and gentex networks, the following maximumlimits should,
9、 in general, not be exceeded:2.1 In national sectionsThe maximum transfer delay of the call-connected signal should not exceed 1250 ms and the maximum signaltransfer delay in the established phase of a call should not exceed 625 ms.2.2 In international sectionsThe maximum transfer delay of the call-
10、connected signal should not exceed 1500 ms and the maximum signaltransfer delay in the established phase of a call should not exceed 750 ms.2 Fascicle VII.1 - Rec. R.58 bisNote 1 A greater transmission delay on international links can be allowed by bilateral agreement if no satellitelinks are used f
11、or national purposes, provided the overall limits on signal transfer delay are not exceeded.3 When considering signal transfer delay, the above tolerances (summarized in Table 1/R.58 bis) apply to thetransmission path between any two terminals of the telegraph, telex or gentex networks and should be
12、 upheld for anyconnection. They may be exceeded only by the delays incurred in the maritime mobile satellite system.Table 1/R.58 bis requires further study.TABLE 1/R.58 bisMaximum signal transfer delay times (en ms)(1)Call-connected signal(2)Signal afterthrough-connection(3)Difference between columns(2) and (3)(4)National section 1250 625 625International section 1500 750 750Overall transfer delay 4000 2000 2000 a)Maritime mobile service 4500 2170 2330a)Maximum value 950 ms when terminating exchange automatically returns the answerback.
