<div dir="ltr">Have you tried spandsp_start_dtmf? It has its quirks but after some tuning It worked for me much better than start_dtmf.<br></div><div class="gmail_extra"><br><div class="gmail_quote">On Tue, Jan 30, 2018 at 1:15 AM, Steve Underwood <span dir="ltr"><<a href="mailto:coppice12@gmail.com" target="_blank">coppice12@gmail.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
  
    
  
  <div text="#000000" bgcolor="#FFFFFF">
    <p>The false positive rate for the DTMF decoder in spandsp is
      extremely low. Tests show it has one of the lowest false positive
      rates in the industry. If you are seeing significant false
      positives you might actually have some DTMF in the audio. Can you
      capture some troublesome audio to a file for analysis?</p>
    <p>Regards,</p>
    <p>Steve<br>
    </p><div><div class="h5">
    <div class="m_-135805356781995241moz-cite-prefix">On 01/29/2018 02:35 PM, Roman Dissauer
      wrote:<br>
    </div>
    </div></div><blockquote type="cite"><div><div class="h5">
      
      Hi Guys,
      <div><br>
      </div>
      <div>we have troubles reliably recognizing DTMF tones by
        using dialplan application start_dtmf.</div>
      <div>From our carriers we get some calls with inband DTMF
        and some with RFC2833. To our customers we need to always do
        RFC2833. Therefore we check SDP information and enable
        start_dtmf when RFC2833 is not available on the incoming call.
        When start_dtmf is executed we have a lot of false positives
        mostly at the start of audio but also during the call.</div>
      <div><br>
      </div>
      <div>Is there a way to prevent false DTMF detection? Does
        anyone have same issues and a solution for it?</div>
      <div><br>
      </div>
      <div>Kind regards<br>
        <div>
          <div>Roman Dissauer</div>
          <div><br>
          </div>
          <div>
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