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:
Feb. 26, 1991
Filed:
Sep. 25, 1989
Toshiaki Takahashi, Tokyo, JP;
Yasuji Sato, Tokyo, JP;
Kabushiki Kaisha Toshiba, Kanagawa, JP;
Abstract
The present invention disclose a switching system including an exchange coupled to a plurality of central office lines and PBX's telephone lines, and a plurality of telephone sets. Each telephone set includes a side-tone adjusting circuit which adjusts a side-tone in response to a balanced impedance to obtain a suitable side-tone. When the exchange receives a speaking path selection request, representing one of the lines, from the telephone set, it determines one of a plurality of predetermined impedance information and makes a speaking path between the selected line and the telephone set. The telephone set selects one of the balanced impedances in response to the determined impedance information.