JPS6454890A - Central control unit for automatic exchange of common control system - Google Patents

Abstract

PURPOSE:To provide general calling function, and to originate and terminate a call through an unused telephone set after a specified telephone set responds and comes busy by programcontrolling the central control unit of a common control system automatic exchange. CONSTITUTION:The common control system automatic exchange, which connects plural telephone sets 1, 2 and plural trunk lines 8a, 8b, and controls the connecting operation of those by the central control unit 7, is provided with a means 6, by which the central control unit 7 calls plural telephone sets all at once when the call terminates in one of plural telephone sets 1, 2, and the means 7, which, when one of the telephone sets 1, 2, called all at once, is off- hooked, turns said telephone set into a busy state, and at the same time, turns other telephone set into an idle state that the call can be originated or terminated. Thus, the simultaneous calling of the plural telephone sets 1, 2 can be easily performed, and the telephone set other than of the busy state can be given a chance for new call originating or new call terminating, by a program means of the central control unit 7 without a special subscriber's private equipment.