Hot-line device for telephone sets

Details Hot-line device for telephone sets Hot-line device for telephone sets

1987-05-19

1989-01-31

Dwyer, James L.

Telephonic communications

Special services

Abbreviated dialing or direct call

379 51, 379355, H04M 1272

Patent

active

048022080

ABSTRACT:
A hot-line device for telephone sets includes a logic AND gate circuit serving as a central unit with its output to be electrically connected to a control circuit through the keyboard of a telephone set, and its inputs respectively coupled with a hot-line triggering circuit, a dial-tone detection circuit and a ringing detection and delay circuit separately disposed in the telephone set for automatically effecting dialing operation during an emergency situation. Alternatively, the logic AND gate circuit can be replaced with a microprocessor for performing automatic dialing operation through a predetermined program.

REFERENCES:
patent: 3573389 (1971-04-01), Greenstein

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