Entry door answering telephone system

Details Entry door answering telephone system Entry door answering telephone system

1992-07-06

1994-06-14

Chan, Wing F.

Telephonic communications

Telephone line or system combined with diverse electrical...

To produce visual-graphic copy

H04M 1100

Patent

active

053217420

ABSTRACT:
An entry door telephone system having a touch-tone telephone with a keypad and an incoming phone line connected to the telephone. A door speaker phone is switchably connected in parallel with the touch-tone telephone, and a paging module is switchably connected in series with the door speaker phone for completing a circuit between the touch-tone telephone and the door speaker phone in response to a data signal transmitted from the keypad of the touch-tone telephone. For controlling operation of this system, a control box is connected to the paging module, the door speaker phone and the touch-tone telephone such that the circuit between the touch-tone telephone and the door speaker phone is broken in response to a data signal transmitted by the touch-tone telephone. Finally, a power source is connected to the paging module and the control box for supplying power thereto.

REFERENCES:
patent: 3665116 (1972-05-01), Holstrom
patent: 3708629 (1973-01-01), First
patent: 3728493 (1973-04-01), Ter Veen
patent: 3732372 (1973-05-01), Tramontano
patent: 3917911 (1975-11-01), Lesher
patent: 3947641 (1976-03-01), Trell
patent: 4113986 (1978-09-01), Clement et al.
patent: 4172967 (1979-10-01), Porter et al.
patent: 4658095 (1987-04-01), Santiago
patent: 4872194 (1989-10-01), Trell
patent: 4987589 (1991-01-01), Trell

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