Colin T Chambers

US Patent:

45270155, Jul 2, 1985

Filed:

Dec 5, 1983

Appl. No.:

6/558316

Inventors:

Colin T. Chambers - Los Angeles CA
James V. Rhodes - Tempe AZ

International Classification:

H04M 1100

US Classification:

179 84R

Abstract:

A security listening system activated by and transmitting over telephone lines to allow listening for sounds at a remote location over a standard telephone line using a standard telephone instrument at the calling end. The system is connected at the remote site to be monitored across the telephone standard tip/ring pair either in parallel with the standard telephone instrument or in lieu thereof. The system is powered by D. C. voltage obtained by rectifying the telephone voltage or, optionally, by a battery. The unit monitors ring sequences on the telephone line and after a pre-established number, activates the balance of the device. If thereafter during a fixed time duration a pre-established tone signal of minimum duration or longer is applied to the line, the system connects a microphone and amplifier across the telephone line to allow the listener on the other end to hear what is happening in the surrounding area. If the tone is not applied to the line before the timed duration expires, the device deactivates. The need for a tone to connect the microphone is optional.