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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.

Typically this issue occurs due to 3 reasons:

  1. Poor physical layer connection
  2. server is under-performing, causing data loss and bottleneck situation
  3. Timing related issue due to clock synchronization issues (from the lines plugged into the Sangoma card)

For Poor Physical layer connection use wanpipemon to verify the RX level is ideal and the performance counters are not incrementing.
Type the following in your Linux command line:

-> wanpipemon -i wXg1 -c Ta

(replace X above with the Wanpipe port in question).

You will see an output similar to the image below

As seen in the image above, the RX level is ideal at -2.5db
View the Performance Monitoring Counters for increments. If this occurs this is the cause for bad audio. Contact your telco for resolution.
To monitoring the performance counters over time, simply re-type the wanpipemon command a few more times and compare.

For scenarios 2 and 3, visit full troubleshooting information at:
       -> Troubleshooting-Telephony Cards- Overruns & Performance Issues

  • If the above page does not help you resolve your issue with robotic, choppy sound, make sure to have visited the DAHDI Chunk side adjustment page.  This may resolve all your issues. 

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 port number in question
      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:
  • 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 
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