Abstract: A control circuit including a mechanical interrupter provides a plurality of interrupted ringing signal bursts when one of a plurality of intercom stations goes off-hook and first initiates a call to another of the plurality of intercom stations. The interrupter also provides an interrupted voltage to cause a button lamp at the another of the plurality of intercom stations to flash. A call selector circuit and a call routing circuit are coupled to the control circuit and the plurality of intercom stations to provide a connection between the one and the another of the plurality of intercom stations to enable the interrupted ringing signal bursts to be conducted on the connection to the another of the plurality of intercom stations. Logic circuitry is coupled to the plurality of intercom stations and the control circuit to detect when the one and the another of the plurality of intercom stations are both off-hook.

Abstract: A call selector circuit is coupled to all of a plurality of intercom stations and is responsive to a call initiating signal from one of the plurality of stations to provide a first portion of a connection to another of the plurality of stations. A call routing circuit is coupled to the selector circuit to establish a second portion of the connection. A diode matrix is coupled to the routing circuit to establish a third portion of the connection. A relay matrix is coupled to the diode matrix and all of the plurality of stations to complete the connection and enable a calling party in the vicinity of the one of the plurality of stations to page a called party in the vicinity of the another of the plurality of stations. In addition the call selector and the relay matrix cooperate to provide an "all page" mode of operation by establishing a connection between all of the plurality of stations to enable the calling party to page the called party at all of the plurality of stations.