Electronic gating control for manual telephone switchboard

Details Electronic gating control for manual telephone switchboard Electronic gating control for manual telephone switchboard

1987-10-28

1989-04-04

Ng, Jin F.

Telephonic communications

Multi-line or key substation system with selective switching...

With special service

379214, 379321, 379159, H04M 500

Patent

active

048192627

ABSTRACT:
A gating circuit for operation in conjunction with a manual cord telephone switchboard to service multiple operational modes of a subscriber telephone connected for telephone communication to a central office. In one mode, an internal intercom connection is established between the subscriber telephone and the switchboard. In a second mode a secretarial service connection is established allowing direct communication between the switchboard and the central office. A ring detection circuit detects when the subscriber telephone has been rung from the central office.

REFERENCES:
patent: 1541926 (1925-06-01), Davidson
patent: 3341663 (1967-09-01), Stefano
patent: 3786198 (1974-01-01), McNulty et al.
patent: 4574165 (1986-03-01), Smith et al.

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