Yealink SIP-T48G Administrator's Manual page 263

Reset your phone to factory configurations after you have tried all troubleshooting
suggestions but do not solve the problem. Note that all custom settings will be
overwritten after resetting.
To reset the IP phone via web user interface:
1. Click on Settings->Upgrade.
2. Click Reset to Factory Setting in the Reset to Factory Setting field.
The web user interface prompts the message "Do you want to reset to factory?".
3. Click OK to confirm the resetting.
The IP phone will be reset to factory sucessfully after startup.
Note
Reset of your phone may take a few minutes. Do not power off until the phone starts up
successfully.
Factory reset can restore the original password. All custom settings will be overwritten
after reset.
Ensure that the 180 ring workaround feature is disabled. For more information, refer to
180 Ring Workaround on page 131.
Troubleshooting
251