Call waiting notifying apparatus

Calling signal controller

Calling system for enabling speech transmission from a caller to

Central office control of receive and transmit handset volume

Circuit and method for reducing common mode interference in tele

Collective-house control system employing an interface circuit f

Communication apparatus having a communication hold function

Communication apparatus with private branch exchange for communi

Communication console station with priority queuing

Communication system having dynamically assigned station set but

Communication system having multi-mode line selection buttons

Communication system having separate unidirectional information

Communication system with assembly carrier unit

Communication terminal apparatus

Concurrent hunt group searching methods and arrangements

Control and interface apparatus for telephone systems

Control of incoming and outgoing calls in a key system

Control system for a plurality of telephone sets

Controlled power supply for key telephone system

Controlling key-system groups from a distributed control switchi