04523307 is referenced by 102 patents and cites 3 patents.

In a power line carrier telephone extension system for transmitting electrical signals between the telephone line and an extension telephone over the AC electric power line available at a telephone subscriber's premises, that includes a main station for processing signals between the subscriber's telephone line and power lines and two or more extension telephones of the system that plug into the power line, means that provides for two or more of the system telephones to communicate without going on the telephone line (Intercom), even while another system telephone is engaged in an outside telephone call and means are further provided for all telephones of the system to conference in Intercom.

Title
Power line carrier multi telephone extension system for full duplex conferencing and intercom between telephones
Application Number
6/445499
Publication Number
4523307
Application Date
November 30, 1982
Publication Date
June 11, 1985
Inventor
James R Lindquist
Rowley
MA, US
William M Brown
Acton
MA, US
Agent
Hamilton Brook Smith & Reynolds
Assignee
Astech
MA, US
IPC
H04M 11/00
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