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:
May. 26, 1981
Filed:
Sep. 24, 1979
Applicant:
Inventor:
John S Young, Scottsdale, AZ (US);
Assignee:
GTE Automatic Electric Laboratories Incorporated, Northlake, IL (US);
Attorneys:
Primary Examiner:
Int. Cl.
CPC ...
H04M / ;
U.S. Cl.
CPC ...
179 / ; 179 / ;
Abstract
A digitally activated ringing circuit for use in conjunction with a central processing unit of an electronic telephone central office is connected between the central processing unit and a telephone subscriber via the central office switching network. The ringing circuit generates an analog signal representing a particular one of a plurality of possible ringing frequencies to be applied to the subscriber line. The instantaneous values of the ringing signal are approximated by information contained within a read only memory.