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:
Jul. 23, 1991
Filed:
Aug. 22, 1989
Applicant:
Inventors:
Koichi Mizutani, Tokyo, JP;
Isamu Ozawa, Tokyo, JP;
Assignee:
Canon Kabushiki Kaisha, Tokyo, JP;
Attorney:
Primary Examiner:
Assistant Examiner:
Int. Cl.
CPC ...
H04M / ;
U.S. Cl.
CPC ...
370 79 ; 3701101 ; 379 93 ; 379 94 ;
Abstract
A telephone system connected to an ISDN and a public service telephone network (PSTN) includes ISDN and PSTN interfaces and allows connected telephone sets to communicate with the both the ISDN and PSTN through a telephone apparatus main body. When the telephone apparatus main body becomes inoperative due to a power failure or the like, the ISDN or the PSTN is directly connected to one of the telephone sets. The connected telephone set receives operating power from the directly connected ISDN or PSTN, and can serve as a telephone set exclusively for the connected ISDN or PSTN.