摘要 |
In a switched telecommunication network (PSTN or ISDN) between a calling party connected to an ISDN switched digital network and a destination called party whose call number is written "Z", the number "Z" of the destination called party is automatically replaced by a number "Y" for an intermediate site which is connected to the ISDN, and the number "Z" of the destination called party is conveyed to the intermediate site, via the ISDN D channel. This substitution process is extended to interconnections between competing ISDN networks and creates a new kind of signaling for use between public exchanges, intermediate between protocol D and ITU-T semaphore channel number 7.
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