System and method for detecting three-way call circumvention attempts

  • US 9,225,838 B2
  • Filed: 08/02/2013
  • Issued: 12/29/2015
  • Est. Priority Date: 02/12/2009
  • Status: Active Grant
First Claim
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1. A method for detecting an attempted three-way call that takes place during a telephone call, the method comprising the steps of:

  • monitoring an audio stream of the telephone call;

    detecting a hook-flash signal in the audio stream; and

    determining, in response to detecting the hook-flash signal, whether a call progress tone is present in the audio stream that is indicative of the attempted three-way call, the determining including;

    calculating an elapsed time during which a power level of the audio stream exceeds a pre-determined threshold during a time period following the detection of the hook-flash signal; and

    determining whether said elapsed time exceeds a maximum allowable period of time.

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