Method and apparatus for completing telephone calls between subnetworks

摘要

A method and apparatus for completing telephone calls between trunk subnetworks (32,34) overlaid on an ATM backbone (25) is described. Each of the trunk subnetworks include a call manager (44,50) which is configured for exchanging signaling messages with both a common channel signaling network (58) and the ATM backbone network. This permits ATM facility providers to link subnetworks using a common infrastructure so that calls can be effectively diverted from the PSTN (7) between end offices while fully supporting PSTN/ISDN services. This is achieved by using a signaling method in which call request messages are encoded by a first call manager (44) with a parameter so that a second call manager (50) in the signaling path can effect backward call set up between ATM interfaces (40,42) using data from the parameter. The advantage is the extension of call completion between subnetworks overlaid on an ATM backbone using ATM facilities without sacrificing PSTN/ISDN call features.