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:
Sep. 06, 1977
Filed:
Jan. 17, 1977
Kiyoshi Urui, Tokyo, JA;
Abstract
There are disclosed first and second groups of internal office trunks used for an exchange. Each internal office trunk comprises first and second terminals for connecting two subscribers' telephones through a switching matrix circuit according to a demand signal from a central controller. The internal office trunks of the second group respectively further comprise a third terminal. The third terminal is connected to a switching circuit controlled by the central controller. The switching circuit controls a mutual connection of the internal office trunk circuits. As a result of being connected to the third terminal mutually by the switching circuit, the second group of the internal office trunks operates as a conference trunk.