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:
Mar. 31, 1998
Filed:
Jan. 20, 1995
Applicant:
Inventor:
Torbjorn Ivar Randahl, Nacka, SE;
Assignee:
Telefonaktiebolaget LM Ericsson, Stockholm, SE;
Primary Examiner:
Assistant Examiner:
Int. Cl.
CPC ...
H04M / ;
U.S. Cl.
CPC ...
379382 ; 379377 ; 379399 ; 379373 ;
Abstract
A method and an apparatus for off-hook detection in a subscriber line interface circuit responds to a ringing signal which preferably lacks a DC component. A signal is generated that is a function of the line current through the subscriber line, and the time at which the signal exceeds a predetermined current value is measured. The measured time is compared with a predetermined time value, and an off-hook indication is produced in a processor depending on the comparison.