At&t Bell Laboratories

Deirdre T Ryan

Nuri Ruhi Dagdeviren

Andreas Constantine Papanicolaou

Cheng D Yu

Walter Patrick Binns

Khashayar Mohammadi

In a video telephony system, a coaxial cable network, which is preferably a part of an existing cable television system, provides a local link for the transmission of the video telephone signals between each originating and destination location and a respective 'head end' located on the cable company premises. Each of the head ends is connected to a 'point of presence' of a telephone interexchange carrier so that a connection between pairs of head ends, and thus between a pair of video telephone locations, can be made via a switched digital network maintained by the carrier. Certain of originating and destination locations comprise a standard television set, serving as the audio/video display, and a consumer-type camera or camcorder, serving as the audio/video source. Others of the originating and destination locations comprise ISDN video telephones which are connected to the various points of presence of the interexchange carrier via local exchange carrier telephone networks. The video telephone number for cable subscriber locations are administered to be the same as the standard ten-(i.e., area code plus seven-) digit telephone number used for regular telephone calls directed to those locations.

Bidirectional video telephony between cable television and switched

This invention relates to a method and apparatus for establishing connections over a public switched telephone network to a customer whose telephone number is in a block associated, for routing purposes, with a first telephone switching system, but who is actually served by a second telephone switching system. The facility for carrying out this method is desirable in order to serve customers who need the advanced functions of a digital switching system, who are currently served by an analog switching system, and do not wish to have their telephone number changed when they switch to being served by the digital switching system. In accordance with the invention, a centralized database is queried to find the identity of the switch serving the called customer. The database returns a routing index for routing the call to that switch.

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Westfield, NJ, United States of America

Deirdre T Ryan