Line switching circuit for cordless telephone

Abstract

A line switching circuit for a communications system which includes a cordless telephone and gives priority of use to an ordinary telephone associated with the cordless one is disclosed. The circuit includes a current detector for detecting a current which flows through the telephone, a circuit having a time constant on only one of positive going edges and negative going edges of an output of the current detector, a relay interposed between the cordless telephone and a subscriber's telephone line, and a driver for driving the relay. The relay is closed immediately upon change of the telephone from an off-hook state to an on-hook state and opened with a predetermined time constant upon change of the same from an on-hook state to an off-hook state, whereby a hand-over of conversation between the telephones may be effected without any malfunction even if a ringing signal from a central office is received.