Answer supervision over pulse code modulated carrier system and

Apparatus and method for automatically reconfiguring telephone n

Apparatus and method for transmitting-receiving CID in a PBX

Apparatus for controlling key telephone station set in key telep

Automated access facilities for use with key telephone systems

Automated access facilities for use with key telephone systems

Automatic redial in a key telephone system having different line

Break-in method in a key system

Button telephone equipment for display of calling public line nu

Call coverage arrangement

Call processing system with resources on multiple platforms

Call waiting notifying apparatus

Calling system for enabling speech transmission from a caller to

Central office control of receive and transmit handset volume

Communication system having multi-mode line selection buttons

Concurrent hunt group searching methods and arrangements

Control system for a plurality of telephone sets

Controlling key-system groups from a distributed control switchi

Digital voice conferencing bridge

Electronic gating control for manual telephone switchboard