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:
Dec. 09, 2003
Filed:
Oct. 08, 1998
Hisashi Amagasaki, Fukuoka, JP;
Fujitsu Limited, Kawasaki, JP;
Abstract
According to the present invention, a maintenance operator can optionally or automatically test not only normality of a frequency shift keying (FSK) signal calling circuit but a specification, a transmission protocol and a standard of a signal length of FSK signal. An exchange system for transmitting information, such as a caller number, to a subscriber line circuit by employing a frequency shift keying signal, the exchange system comprising: a loop circuit for imitating a loop of a subscriber's telephone set; and a firmware for receiving a frequency shift keying signal and judging the normality of the frequency shift keying signal, wherein the firmware controls to open and close the loop circuit according to testing on On-Hook or Off-Hook protocol.
Data source: USPTO (United States Patent and Trademark Office) public patent records. Weekly synchronization. How IDiyas builds this profile