џWPCL ћџ2BJ|xа АH аа АА X агга ХА6p&А6p&Х аеЄ† а Hр аааУ Уб cмˆ4 PŽТ б Fascicle VII.2 Р-Р Rec. U.75 PAGE1 Єее† а HH аааУ Уб cмˆ4 PŽТ бPAGE2 Fascicle VII.2 Р-Р Rec. U.75 еа H№ ааЬџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџHpи P Ј XА`ИhР!(#џџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџЬаа X  аб cмˆ4 PŽТ бTHE DRAWINGS CONTAINED IN THIS RECOMMENDATION HAVE BEEN DONE IN AUTOCAD. ‚У УRecommendation U.75 аЬџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџH јP Ј XА`ИhР!(#џџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџЬаСр(DСб cмˆ4 PŽТ бAUTOMATIC CALLED б cмˆ4 PŽТ бTELEX ANSWERBACK CHECK аЬџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџHpи P Ј XА`ИhР!(#џџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџЬаСр(<Сб cмˆ4 PŽТ бФ ФУУ(MalagaР-РTorremolinos, 1984; amended at Melbourne, 1988)ФФ аЬџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџHјP Ј XА`ИhР!(#џџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџЬаТа ТThe CCITT,ЦЦ аЬџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџHpи P Ј XА`ИhР!(#џџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџЬаУУconsidering а H аФФС С(a)СpСthat there is a need to check the answerback of the called telex number [e.g. delivery from a telexР-РTeletex conversion facility (CF)/ or store and forward unit (SFU)]; а H аС С(b)СpСthat Recommendation F.60 defines a preferred structure for the telex answerback; С С(c)СpСthat different forms of answerback exist, а H аС С(d)СpСthat Recommendation F.60УУ bisФФ defines a structure for a telex answerback associated with an intermediate document storage device; УУunanimously declares а H аФФС Сthat the following requirements are recommended for automatic answerback check of a called telex terminal by an administration's equipment: а H ааЬџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџHјP Ј XА`ИhР!(#џџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџЬа‚У У1ТX ТCase 1: reference information for the check is provided by the calling subscriberФ ФЦЦ аЬџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџHpи P Ј XА`ИhР!(#џџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџЬаС СThis information can be in total or part of the called subscriber answerback (contiguous printable characters and space). There is no restriction on the number of characters supplied. а H аС СIn this case, the called party answerback check consists of verifying the presence of the provided character string. Considering the information provided in the directories and terminal identifications, allowance is to be made for the following differences: Та ТР-РТ№ Тone character mismatch in the letter part;ЦЦ а Hh аТа ТР-РТ№ Тone hyphen or one space is ignored in the national call number.ЦЦ а Hx ааЬџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџHјP Ј XА`ИhР!(#џџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџЬа‚У У2ТX ТCase 2: no information on the answerback of the called terminal is provided by the calling subscriberФ ФЦЦ аЬџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџHpи P Ј XА`ИhР!(#џџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџЬаС СThe reference information for the answerback check is the selection information provided by the calling subscriber. С СIn this case, the called party answerback check consists of: а H аТа ТР-РТ№ Тextracting the national call number and F.69 code from the answerback;ЦЦ а H аТа ТР-РТ№ Тcomparing the obtained national call number and F.69 code with the supplied selection information code. Allowance is made for the following cases of mismatch:ЦЦ а H аТа ТТ№ ТТhpТС€Сa)Си Сa positive national call number match without a valid telex national identification code (TNIC) match,ЦЦ а Hx аТа ТТ№ ТТhpТС€Сb)Си Сa match between the least significant part of the supplied selection information and the national call number obtained from the called party answerback, considered to be positive if the difference in field length is limited to two characters.ЦЦ а H аУ У3Ф ФС СAn algorithm which meets the preceding criteria for cases 1 and 2 is shown in Figure 1/U.75 а H аС СIn some circumstances, it may be necessary to compare the answerback of the called subscriber with the answerback received and recognized at the beginning of the call. а H аС СIn such cases, if the received string consists of more characters than the previously recognized answerback, then a check should be made as to whether the recognized answerback is part of the received string. ‚Ср LСб cмˆ4 PŽТ бFIGURE 1/U.75 Љ CCITT 76220 б cмˆ4 PŽТ б а H аадаб cмˆ4 PŽТ бУУNote 1ФФ Р-Р Check the automatic emitting speed and wait for the end of the answerback. The answerback is considered to have ended after detection of a 300 ms period of idle. УУNote 2ФФ Р-Р Р"РRetryР"Р refers to another attempt to trigger the answerback. УУNote 3ФФ Р-Р If unsuccessful, perform one retry if allowed in the protocol. а H аУУNote 4ФФ Р-Р The answerback provided could be a contiguous part of the expected answerback or all of it. а H аIn case of a return call to the calling subscriber (e.g. PDN (positive delivery notification) or NDN (negative delivery notification) delivery) the stored calling telex answerback is considered as a Р"РprovidedР"Р one. а H аУУNote 5ФФ Р-Р This comparison is to verify the presence of the provided character string in the received answerback, allowing one character mismatch in the letter part. а H аУУNote 6ФФ Р-Р A zero in the selection, but not in the answerback in front of the national number is to be ignored. If the received figure group is shorter than the selected one, consider it as match, but make a note in the call record Р"Рreceived figure group is not completeР"Р. It is possible that the received figure group includes the F.69 code. а H аУУNote 7ФФ Р-Р Forward message, but make a note Р"Рarea codeР-Рcheck was not possibleР"Р into the call record. УУNote 8ФФ Р-Р If called A/B is not available from previous procedures. а H аУУNote 9ФФ Р-Р If a digit Р"Р0Р"Р appears at this stage between the F.69 code and the Р"РNCNР"Р it should be ignored. ааб cмˆ4 PŽТ б