FXO Impedance Match Tool Instruction

  • Applicable Model: S-Series, P-Series
  • Applicable Firmware Version:  S-Series 30.10.0.X or higher ( Firmware 65.X.X.X was not supported.), P-Series 37.5.0.X or higher
  • Scenario: FXO port voice quality issues – Echo, white noise, bad voice quality etc.

Step 1. Initialize the FXO port settings

Set the default volume on each FXO ports (RX 40%, TX 40%). And check Echo Cancellation option. (In some extreme situation, please uncheck this option. Yeastar support to do it when needed.)

PSTN lines should be connected on FXO ports already. Or the whole process would be meaningless.


Step 2. Login SSH of S-Series PBX followed by this guide:

How to Log in SSH of Yeastar S-Series VoIP PBX


Step 3. Create FXO impedance debug marked file.

Create the marked file by command:

cd /ysdisk/support/fxotune

touch .detect_fxomode

Check if the file exists

ls -al

Step 4. Reboot PBX to perform the impedance match process.

You could use command “reboot” or reboot from web.

The process would takes about 2-3 minutes per FXO port.  So if you have 5 ports, that might takes about 10-15 minutes to finish the whole process.

To check if the process is running or finished. You could use command: ps


Step 5. Check fxotune config file which is for impedance.

vi /ysdisk/support/fxotune/.fxotune.conf

Check if all ports has been performed the impedance match. One line for one port, and the impedance value could be different for each port.

Step 6. Make call tests.

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