Method and apparatus for controlling telephone line access

Telephonic communications – Call or terminal access alarm or control – At substation

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Details

379387, 379 61, H04M 166

Patent

active

046835830

ABSTRACT:
A security device to protect a telephone line from unauthorized outgoing calls from a telephone unit, comprising either a conventional or cordless type receiver, which includes an access limiter and bypass circuit interposed between the base telephone and the telephone line which responds to an access enabling device to unblock the access limiter and bypass to outgoing calls. In one form, the access enabling device is an electronic circuit which responds to a multidigit dial signal to unblock the outgoing calls. In a simpler form, the access enabling device includes mechanically actuated device, such as a lock and key, to block and unblock outgoing calls.

REFERENCES:
patent: 4087638 (1978-05-01), Hayes
patent: 4099033 (1978-07-01), Murray
patent: 4179588 (1979-12-01), Oliveira et al.
patent: 4246445 (1981-01-01), Hayasaka
patent: 4251692 (1981-02-01), Waldman
patent: 4291197 (1981-09-01), Yonaga
patent: 4358640 (1982-11-01), Murray
patent: 4436957 (1984-03-01), Mazza
patent: 4467140 (1984-08-01), Fathauer et al.
patent: 4482787 (1984-11-01), Sagara et al.
patent: 4511765 (1985-04-01), Kuo

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