US 4,158,111 AGranted

Exclusion system for a key telephone system

AssigneeInternational Telephone and Telegraph Corporation

InventorBruce R. Saxon

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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.

Claims31

Dependent claims

An exclusion system for a central office/private branch exchange (CO/PBX) system and a party line paging and intercom system, said CO/PBX system having an "A" lead, a tip conductor and a ring conductor and said party line system having an "A" lead, a tip conductor and a ring conductor comprising:

first means coupled to said "A" lead of said party line system when said party line system is selected and responsive to a predetermined potential on said "A" lead of said party line system to coupled a tip conductor and a ring conductor of an associated subset to said tip and ring conductors of said selected party line system;
wherein said first means is coupled to said `A` lead of said CO/PBX system when said CO/PEX system is selected and is responsive to a predetermined potential on said `A` lead of said CO/PBX system to couple to the tip conductor and the ring conductor of said associated subset to said tip and ring conductors of said selected CO/PBX system;
second means coupled to said "A" lead of said party line system to manually generate a first exclusion potential for said party line system to exclude subsets not already connected to said party line system;
and
third means coupled to said "A" lead of said CO/PBX system responsive to a given potential on said "A" lead of said CO/PBX system to automatically produce a second exclusion potential on said "A" lead of said Co/PBX system to exclude subsets not already connected to said CO/PBX system.

2 more elements

Dependencies are inferred from the claim text.