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:
Apr. 27, 1999
Filed:
Oct. 13, 1995
Frank B Manning, Boston, MA (US);
William Hume Vance, Somerville, MA (US);
Zoom Telephonics, Inc., Boston, MA (US);
Abstract
A parallel-connected dialing signal detection and transmission-inhibiting device is disclosed which detects dual-tone multi-frequency dialing signals across tip and ring conductors of a telephone link and switches in an a.c. load that attenuates the dialing signals by at least 30 dB. This prevents action in response to the DTMF signals by a central office servicing the telephone link, thereby allowing commands-data to be transmitted within the home telephone wiring. Such commands can be used to invoke a speed/auto dialing function, to provide an intercom, to control appliances, etc. To allow fast response, the controller charges a capacitor of the a.c. load by connecting it across the tip and ring conductors in response to an off-hook condition. Then it is disconnected to allow a dial tone to reach a user at the telephone. Further transparency is provided by the fact that a single interfacing capacitor connects both the dialing signal detector and a tone generator to the tip line. This reduces the loading on the tip line by the device during periods when users are conversing on the telephone link.