Ringing control device

Abstract

A ringing control device for a group of subscriber lines served by a connection network, comprising a relay for each line, the connection network providing a ringing control signal and a timing signal for controlling the relay, a ringing generator common to the group of lines and providing an A.C. ringing current to a line when the corresponding relay occupies a first position, a supervisory circuit for each line, connected thereto in the second position of the relay and delivering a signal to the connection network if the receiver is lifted while the relay occupies said second position, and a common off-hook condition detector delivering a signal if a D.C. current appears, due to the receiver being lifted, on at least one of the lines of the group while a ringing current is being fed (first position of the relay), wherein the ringing control device comprises an AND circuit receiving from the connection network the ringing control signal and the timing signal and connected to the supervisory circuit and to the off-hook condition detector and whose output signal controls the relay.