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DTMF SIP trunk

Discussion in '3CX Phone System - General' started by mixig, Sep 7, 2017.

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  1. mixig

    mixig Active Member

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    Hi,
    in v15.5 I still don't see possibility to setup DTMF method on trunk?
    Is that correct or I am doing something wrong?

    Assume that customer has two VoIP provider (one for local and other for international calls) where one of them supports INBAND and another one RFC DTMF, and lets say on the phone is INBAND
     
  2. Saqqara

    Saqqara Well-Known Member

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    I would have thought this is configured on the SIP line by the provider and not within 3CX. I would speak to the company providing the lines.

    We have SIP lines, and do not have to do anything with DTMF settings.
     
  3. leejor

    leejor Well-Known Member

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    You should be able to configure DTMF Method on your sets, or a gateway. Most sets default to a "auto" setting and will use whichever method is best, at the time. In many cases INBAND is sent if you can hear DTMF tones in the receiver. However SIP messaging is the most reliable, as the tones are regenerated at the far end if needed. Some low bit rate Codecs have difficulty passing audio DTMF.
     
  4. mixig

    mixig Active Member

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    Thanks for the advice, I will try with auto, but the question is why 3CX did not implement DTMF option on trunk so far, asterisk for example, has that possibility for many years.
    I belive this is reasonble request.
     
  5. leejor

    leejor Well-Known Member

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    So I'm assuming that that having a DTMF Method option option on a VoIP trunk will intercept audio DTMF then convert to a SIP message? When you select the method on a set, that is what is sent to the far end. If it is SIP message then that should be passed onto your provider. If you choose to limit to only audio, then there is a greater chance it won't reach the far end, but that depends on a number of factors.

    https://www.voipmechanic.com/dtmf-issues.htm
     
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