ITU-T U 6-1988 PREVENTION OF FRAUDULENT TRANSIT TRAFFIC IN THE FULLY AUTOMATIC INTERNATIONAL TELEX SERVICE《国际用户电报网与海上卫星系统接口需满足的一般要求》.pdf

1、INTERNATIONAL TELECOMMUNICATION UNION)45G134 5 TELECOMMUNICATIONSTANDARDIZATION SECTOROF ITU4%,%2!0(G0G037)4#().%.%2!,02%6%.4)/.G0G0/ amended at Geneva, 1964)The CCITT,considering(a) that, with fully automatic working in the international telex service, the possibility of fraudulent routing bysubscr

2、ibers of international calls involving tandem connection of international telex trunks might arise wheneversubscribers are given automatic access to international telex trunk circuits that have, at their incoming ends,automatically switched access to other international telex trunk circuits;(b) that

3、, by the adoption of a systematic plan, such traffic can be barred without involving either expensive orelaborate equipment arrangements;(c) that, to be effective, such a plan would need to be adopted by all Administrations and recognized privateoperating agencies since failure to provide barring fa

4、cilities on the traffic between two countries could open the wayfor irregular routings at the expense of a third country,unanimously declares the view(1) that national telex systems shall be so arranged that the first digit of the selection signals transmitted overincoming international telex trunks

5、 will indicate whether an automatic transit call is concerned;Note The use of a common first digit to indicate access to both international telex trunk circuits and manualswitchboards leads to complication in the barring arrangements and should therefore be avoided as far as possible.(2) that where

6、an international telex trunk carrying fully automatic traffic also carries traffic requiring access atthe incoming end to outlets selected by means of the digit characterizing an automatic transit call, the country of originwill bar irregular routings by discriminating on the digits transmitted by c

7、alling subscribers;(3) that where an international telex trunk carrying fully automatic traffic does not carry traffic requiringaccess at the incoming end by means of the digit characterizing an automatic transit call, the incoming equipment shallbe so arranged that the corresponding outlets are not

8、 accessible and that when access is attempted the numberunobtainable signal is returned;(4) that it is not admitted that two Administrations can agree to omit the provision of barring facilities ontraffic between their respective countries. However, where the incoming country has an existing network in whichconsiderable difficulty would be experienced in barring in accordance with 3 above, the responsibility for barringmay, by agreement, be assumed by the country of origin in the manner specified in 2.