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This page will help to resolve the following audio issues:

  • Low volume
  • robottic, choppy sound

Low Volume

If there are issues where the calling or called party hears the remote side too quiet, there is an option in chan_dahdi.conf (located in /etc/asterisk directory) where you can increase the gain in either direction.

  • Open /etc/asterisk/chan_dahdi.conf
  • locate:
    • Gain Settings: increasing / decreasing the volume level on a channel.
    • The values are in db (decibells). A positive number will increase the volume level on a channel and a negavive value decreases volume level.
    • There are several independent gain settings: rxgain: gain for the rx (receive - into Asterisk) channel. Default: 0.0
    • txgain: gain for the tx (transmit - out of Asterisk Asterisk) channel. Default: 0.0 
  • Change the gain value according to your needs
  • restart Asterisk for changes to take affect
  • Make your test call where the issue should be fixed
  • If the issue still persists, then the issue is either on your SIP side, or your telco side (the Sangoma card does not have any affect on the audio volume)

Robotic, choppy Sound

The following information will help you resolve an issue where calling parties and/or users hear weird sounds, static, choppy and robotic audio.

For poor physical layer connection use wanpipemon to verify the voltage level is ideal.

Type the following in your Linux command line:
wanpipemon -i w1g1 -c astats -m X
(replace X above with the channel/port number in question).
w1g1 represents the naming convention for the entire analog card. If you have more than one Sangoma card in your system, you need to change w1g1 to the analog card. Check the output of the Linux ifconfig command to find correct name if needed)

A proper output for an FXO line is

If the output you see is significantly different (i.e. voltage= 3 volts, or 70 volts), then you must check your physical line connection as possible reason for your issue)

If your card has a hardware echo canceller try disabling it during the time of issue, incase the issue is due to your card itself:
  1. Make your call that experiences the issue
  2. Identify which port the call is on, that is having audio issues
  3. Type the following command to disable the hardware echo canceller immediately:
    1. wan_ec_client wanpipeX disable
      1. replace X with the analog card number in question (typically this is '1')
      2. if successful you will notice the following output
  4. If you notice all the audio issue go away, please contact Sangoma support at
  5. If there is no difference you can re-enable the hardware echo canceller via the following ways:
    1. type: wan_ec_client wanpipe1 enable
    2. restart wanpipe: wanrouter restart

If non of the above info has assisted, it is time to take an Audio trace to narrow in on the issue:
To take an audio trace please visit this link: Capture Audio Recording from card
  • If your Card has a hardware echo canceller, take a HWEC trace and a dahdi_monitor trace
  • If your Card does NOT have a hardware echo canceller, take only a dahdi_monitor trace 
Once you have taken your audio trace(s), please submit them to Sangoma support for analysis at 
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