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:
Sep. 24, 1996
Filed:
Mar. 13, 1995
Richard Panosh, Bolingbrook, IL (US);
Other;
Abstract
A device is provided to prevent an unauthorized telephone unit from initiating a telephone call, where the unauthorized telephone unit is connected between the central office of the telephone company and the authorized telephone units of the user. The device includes a first detector for detecting a DC current within the lines, and a second detector for detecting the voltage across the lines which lead from the telephone office to the authorized phones. A third detector detects a dual tone multifrequency dialing signal on the line, and a fourth detector detects pulse dialing, and a logic is responsive to all four detectors. When a dialing attempt is made from an unauthorized telephone unit, the first detector will not detect a DC current in the lines to the authorized telephone units, the second detector will detect a drop in voltage across the ring and tip lines, and either the third or fourth detector will detect that a dialing effort is being made. Where an unauthorized dialing is detected, the logic switches a blocking device between the lines to block the unauthorized dialing efforts.