Premises page/intercom system utilizing telephone set component

Patent 4754476 Issued on June 28, 1988. Estimated Expiration Date:

March 2, 2007. Estimated Expiration Date is calculated based on simple USPTO term provisions. It does not account for terminal disclaimers, term adjustments, failure to pay maintenance fees, or other factors which might affect the term of a patent.

Abstract Claims Description Full Text

Patent References

Hold control for a key telephone system
Patent #: 4132860
Issued on: 01/02/1979
Inventor: Rasmussen

Key telephone system having interstation signalling during hold condition
Patent #: 4228324
Issued on: 10/14/1980
Inventor: Rasmussen , et al.

Interface circuit for telephone line to equipment signal coupling
Patent #: 4323734
Issued on: 04/06/1982
Inventor: Kimzey

Key telephone system signalling and control arrangement Patent #: 4511767
Issued on: 04/16/1985
Inventor: Wetzel , et al.

Inventors

Application

No. 07/021608 filed on 03/02/1987

US Classes:

379/159, With intercom system379/160, With connection of intercom station to subscriber line379/164Line status indication or call alerting

Examiners

Primary: Dwyer, James L.

Attorney, Agent or Firm

Barnard; Delbert J.

International Classes

H04M 11/02 (20060101)
H04M 1/72 (20060101)
H04M 1/723 (20060101)
H04M 3/42 (20060101)
H04M 9/02 (20060101)

Abstract

A premises in which a plurality of telephone sets (10, 12) are used is provided with dedicated intercom wiring (1, 6) having its own power source. Each telephone set (10, 12) includes standard telephone circuitry (20), for communicating off premises, and also includes an intercom circuit (21). A switch (22) is provided for switching the receiver and transmitter (HS) of each set (10, 12) between off premises communications and intercom use. Each set (10, 12) includes a paging speaker (LS1) that is a part of the intercom system. To page, a button (96) is depressed at one station and the user talks into the transmitter at that station. The transmitted message is broadcasted through the speaker (LS1) at each telephone set in the system except the one that is sending the message. The intercom system control utilizes the same wire over which the audio signal is transmitted. The paging circuitry is off when the system voltage is at a particular level and is turned on by changing the system voltage to a different level.