The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
May. 09, 1978
Filed:
Mar. 30, 1977
James R McEowen, Holmdel, NJ (US);
Bell Telephone Laboratories, Incorporated, Murray Hill, NJ (US);
Abstract
An intercom system for single-line customers is disclosed which utilizes the existing nonkey telephone sets and four-conductor wiring plan together with an additional adjunct per telephone and a common control unit. Hold, broadcast intercom, and their associated visual signals are controlled by each adjunct unit which is interposed between the associated telephone set and the existing four-conductor telephone cable. Normal voice signals and supervision are transmitted using one pair of the four-conductor cable. The second pair of the cable is used for signaling between the common control unit and the adjuncts as well as for supplying power to the adjuncts. The operation of a single nonlocking key at any adjunct places the system in the intercom mode and concurrently places an active central office line on hold. Conclusion of an intercom conversation is accomplished when all telephone sets go on-hook. A held central office line is then connected to the next party to go off-hook.