Abstract: A service circuit for a local telephone line in a building wired with quad telephone conductors, including a tip and ring lead pair continuous with a subscriber's line connected to a remote switching machine, and a service lead pair within the building. A special service circuit is connected to the tip and ring lead pair and to the service lead pair. A control unit is also connected to the tip and ring lead pair and the service lead pair for receiving signals over either the tip and ring pair or the service lead pair from a telephone connected to the local line, and for generating a predetermined special service circuit enabling signal on the service lead pair. The enabling signal is received by the special service circuit which implements one or more special services in response thereto. The control unit also applies operating power to the service lead pair. The special services implemented include intercom, paging, tone ringing, etc. The control unit also provides power, control, rapid dialing signals, etc.

Abstract: A telephone system used in the home which provides special services such as intercom, paging, remote turn on or off of power contacts, audio monitoring, etc. A central control is interposed between the subscriber's line and the local wiring in his home, or is connected in parallel thereto. One or more telephone subscriber sets are plugged into the wiring as usual, contacting the tip and ring leads. In the present invention, remote special service circuits are plugged into the telephone line, contacting the remaining two conductors, referred to below as the black B and yellow Y leads. Each of the remote special service circuits has a specialized function, e.g., a typical circuit will have a speaker, an amplifier for driving the speaker, and a circuit for enabling the amplifier and connecting it across the black and yellow leads once an address has been received on the black and yellow leads.