Patent
1978-01-13
1979-06-12
Claffy, Kathleen H.
179 17B, 179 39, 179 99E, 179 99P, H04Q 520
Patent
active
041581113
ABSTRACT:
The exclusion system is employed with a central office/private branch exchange (CO/PBX) system and a party line paging and intercom system. A first circuit is coupled to the "A" lead of the party line system and is responsive to a predetermined potential on this "A" lead to couple a tip conductor and a ring conductor of an associated subset of the party line system to the tip and ring conductors of a selected one of the CO/PBX system and the party line system. A second circuit is coupled to the "A" lead of the party line system to manually generate a first exclusion potential for the party line system to exclude subsets not already connected to the party line system. A third circuit is coupled to the "A" lead of the CO/PBX system and is responsive to a given potential on this "A" lead to automatically produce a second exclusion potential on this "A" lead to exclude subsets not already connected to the CO/PBX system.
REFERENCES:
patent: 3872262 (1975-03-01), Kerman
patent: 3941943 (1976-03-01), Matheny
patent: 3961144 (1976-06-01), Hirate
patent: 4000376 (1976-12-01), Springer
patent: 4021621 (1977-05-01), Wycheck
patent: 4053720 (1977-10-01), Wycheck et al.
patent: 4075434 (1978-02-01), Merritt, Jr.
patent: 4081624 (1978-03-01), Kerman et al.
patent: 4117274 (1978-09-01), Cannon et al.
Brigance Gerald L.
Claffy Kathleen H.
Hill Alfred C.
International Telephone & Telegraph Corp.
O'Halloran John T.
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