Speech channel switching networks suitable for use in combination with electronic key telephone sets

摘要

In a key telephone system including an electronic speech channel switching network and an electronic key telephone set selectively connected to central office lines by the speech channel switching network, the speech channel switching network is constituted by a pair of incoming lines connected to a pair of central office lines and a plurality of pairs of outgoing lines connected to the key telephone set. The incoming and outgoing lines are arranged in a matrix, and a plurality of controllable unidirectional switching elements are disposed respectively at four cross-points between the incoming and outgoing lines. Each switching element is connected oppositely with respect to one incoming line and to one outgoing line which comprise a pair.