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Detecting whether a telephone line has been disconnected

  • US 5,450,485 A
  • Filed: 04/19/1994
  • Issued: 09/12/1995
  • Est. Priority Date: 03/08/1993
  • Status: Expired due to Term
First Claim
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1. Apparatus for detecting whether a telephone call has been disconnected, which apparatus comprises:

  • click detector means for detecting a click and for generating a click indication indicating whether or not a click was detected;

    handset impact detector means for detecting a telephone handset impact and for generating a handset impact indication indicating whether or not a handset impact was detected;

    silence detector means for detecting silence and for generating a silent indication indicating whether or not silence was detected;

    means for determining a predetermined time interval and for transmitting a signal to a controller means whenever the time period expires;

    wherein the controller means comprises analysis means, responsive to the signal and to click indications, handset impact indications, and silence indications, for, determining whether a predetermined sequence of handset impact, clicks, and silence was detected and, if so, for generating a signal indicating that the telephone call has been disconnected.

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