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:
Nov. 18, 1997
Filed:
Mar. 29, 1996
Applicant:
Inventors:
Assignee:
Fujitsu Limited, Kawasaki, JP;
Attorney:
Primary Examiner:
Assistant Examiner:
Int. Cl.
CPC ...
G06F / ;
U.S. Cl.
CPC ...
371 201 ; 371 682 ; 370248 ;
Abstract
A data transmission system having, in addition to a normal system operation mode, a test mode wherein a plurality of stations confirm each other through sending and receiving check data for security confirmation and wherein the actual line switching operation is not performed. In the test mode, when notifying test data for confirmation of another station, the call terminating station side notifies the accurate data, while the call originating station side activating the test mode notifies deliberately changed check data thereby enabling a test for confirmation of the continuance of connection with a backup line without suspending communication with the working line.