What codec is used by default?

Discussion in 'General' started by pacini, Apr 24, 2008.

  1. pacini

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    Hi,
    is it 711u? and how do I force a specific codec?
     
  2. jgutierrez

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    Hello,

    yes the default codec is ullaw. You may change it on the /etc/asterisk/sip.conf file, I have:

    disallow=all
    allow=ulaw
    allow=alaw

    that means that I will use the ulaw codec by default, if the device that is registered with elastix can't handle ulaw, it will use alaw, and so on...

    Be careful is you only set to allow gsm, that is because some "hardphones" can't handle that codec, softphones does B)

    By the way, when you are in a call, and if you are the in the CLI, you may type:

    sip show channels

    that will reveal you the codec that you are using in that moment

    Hope, that has helped you
     
  3. pacini

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    Thank you jgutierrez,
    We got a customer with one of our PAP2T using either 729a or 711u trying to use dialup connection and it does not connect. Any ideas?

    PS. Will fax machines also connect by default if used with the above mentioned codecs?

    Thank you
     
  4. elastixguy

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    Dial up is not exactly the most suited connection for voip. But your customer could try disabling 711u and 711a, because this codec is too much for dial up.

    He's better of using 729, which is a compressed codec. As 711 is not compressed.

    A fax machine on the other hand will only work with 711 or t38 codecs.
     
  5. pacini

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    Thank you elastixguy.
     

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