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Apparatus and method for displaying duration of a call made over a central office line in a keyphone system

  • US 5,077,682 A
  • Filed: 09/08/1989
  • Issued: 12/31/1991
  • Est. Priority Date: 12/31/1988
  • Status: Expired due to Term
First Claim
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1. A method of displaying duration of a call made over a central office line in a keyphone system having a plurality of keyphones with displaying means, the method comprising the steps of:

  • (a) activating a call-duration start timer for indicating starting of a call upon the call being started, and then checking whether or not the call is ended;

    (b) if the call is ended in the step, checking whether or not a call-duration time indicated on said displaying means is at a standstill;

    (c) if the call is not ended in said step (a) and a time key is not depressed, checking whether or not a control signal for activating said call-duration start timer or a call-duration timer is applied thereto, said call-duration timer being for counting duration of said call and generating a call-duration time;

    (d) checking whether or not the central office line is at a holding state in response to said control signal and, if not at said holding state, sending a value of said call-duration time to said keyphone to display the call-duration time on a said display means; and

    (e) if said time key is depressed and said call-duration time indicated on said display means is at a standstill in said step (b), clearing the call-duration time displayed on said display means to display a current time.

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