Handsfree loudspeaking key telephone set and a switching circuit for use in a microphone and loudspeaker equipped key telephone

摘要

A key telephone system is disclosed comprising microphone and loudspeaker equipped key telephone sets in which intercom calls are received through the microphone and loudspeaker. Additionally, the microphone and speakers may be used for central office calls. When so used, brief intercom calls can be allowed to break in, automatically placing the central office call on hold.