04514594 is referenced by 76 patents and cites 16 patents.

In a power line carrier telephone extension system for transmitting electrical signals between the telephone line and one or more extension telephones 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 one or more extension telephones of the system that plugs into the power line, all of which can place calls to the telephone line, answer calls from the telephone line and conference together in full duplex communication, means at the extension telephones for initiating a telephone line hold signal that is transmitted over the power line to the main station where the hold signal is detected and initiates connecting a hold impedance across the telephone line.

Title
Power line carrier telephone extension system for full duplex conferencing between telephones and having telephone call hold capability
Application Number
6/430762
Publication Number
4514594
Application Date
September 30, 1982
Publication Date
April 30, 1985
Inventor
James R Lindquist
Rowley
MA, US
William M Brown
Acton
MA, US
Agent
Hamilton Brook Smith & Reynolds
Assignee
Astech
CT, US
IPC
H04M 11/00
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