CEPT T SF 50 E-1987 PABX Internal Dial Call《交换机内部拨号》.pdf

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1、CEPT T/SF*KSO*E 87 m 2326434 0009432 7 m T/SF 50 E Page 1 Recommendation T/SF 50 (Copenhagen 1987) PABX INTERNAL DIAL CALL Recommendation proposed by Working Group T/WG 7 “Services and facilities“ (SF) Text of the Recommendation adopted by “Teleconniitnicntioiis” Commissioit : “The European Conferen

2、ce of Posts and Telecommunications Administrations, considering - a dialtone at the beginning of an originating call i.e. ergonomic desirable, - the first dialtone of the public network shoulb be a continuous tone of 425 Hz according to CEPT Recommenda- tion T/S 20-15 and/or a continuous tone, one t

3、one within a bandwith of 340-435 Hz and one within a bandwith of 400-450 Hz, according to CEPT Recommendation T/SF 23, - different telephone set configurations with direct public lines or extension lines, sometimes on the same set, exist, - therefore after dialling a public line the extension user o

4、f a PABX shoulb be aware that a public line has been - different solutions are possible, e.g. by absolute or relative distinguishability, accessed, O recommends - that an internal PABX dialtone is desirable, - that this tone should be continuous, - that a double tone should be used, - that this double tone should be distinguishable from the public dialtone, - that distinguishability should be reached by the distinction: - double tonelsingle tone, or by - a considerable difference in frequency.” Edition of January 15, 1988