How to Adjust Volume of FXS/FXO in MyPBX


When FXO/FXS are installed in MyPBX, the volume value by default is enough. Sometimes it’s too low caused by the PSTN line or others. In this case, we can adjust the volume on web directly. If the modification still cannot meets your request, we can customize the volume via SSH access.

Adjust volume on web (recommend)

For FXO, we can adjust it in PSTN page, click ‘trunk’’Edit’ and change’Volume Setting’ directly,and that means ‘Txgain’. The default values of them are 40%.

Note: The default value 40% is fine for general trunks, we recommend to keep it by default. If it’s really needed to increase the volume, we can configure it here.

For FXS, we can edit this extension and change the volume too. Click ‘extensions--Edit’ and change volume settings.

Note: There is no need to modify the settings for FXS extension. We can modify it in extension page for the exact value of txgain and rxgain, which is much simpler than modifying it via SSH.

Adjust volume via SSH access (For FXO)
Here are the detailed steps to adjust the volume via SSH access.
Step1. Enable SSH access in ‘LAN settings’ page.Then click “Apply Changes” to take effect.

Step2. Download putty.exe and log in via ssh access.
 Here is the download link for
 Open it, input MyPBX’s IP address and the SSH port,in this example, IP is, port : 8022.

Step3. Click ‘Open’, input the default user name and password
           User name: root
           Password: ys123456

Step4. Check the FXO channel you want to modify
           Input command: vi /etc/asterisk/users.conf

Step5. Please find the pstn trunk you want to modify, in this example, the trunk name is ‘pstn3’, which we can find on web too.

Find the details of this trunk, we can find both value of rxgain and txgain are 0.

Step6. Create customized configuration file to save the value we want to set for rxgain and txgain.
The command is: vi /persistent/custom-cfg/users_custom.conf

We need to input the contents including the value we want.
In this example, the value of txgain and rxgain of pstn 3 is 15.
So the content should be:
        rxgain = 15
        txgain = 15

Note: the value should not be more than 15 for rxgain and txgain, or it will cause noisy signal.

Step7. After finishing typing, press “Esc” key to exit Insert Mode, then Type command “:wq” to save and quit. Then click ‘apply the changes’ on web to reload the modification before testing.

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  • 0

    Hi Sir/Ma'am, In connection to above topic "How to Adjust Volume of FXS/FXO in MyPBX". Speaks about the volume of the "sound" or voice on the line?

  • 0

    Hello, it has been my experience that the call quality on PSTN lines in MyPBX is not very good. I am located in Canada and it has been a recurring theme with analog telephone lines connected to FXO cards. A proper fix would be greatly appreciated.



  • 0

    Hello, I know how to adjust the volume. The problem is the quality of the sound is very bad on analog trunks when I increase the volume. Is there any way to improve on that?


  • 0

    Hello Tasso, 

    Can you please describe in more detail about the call quality issue? Did the issue happened on one Yeastar device or on multiple Yeastar MyPBX? Did you ever try contact with any of Yeastar support engineer for this issue? I would suggest to create ticket for this issue so that our team can track and fix the issues properly.

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