Yealink SIP-T48G Administrator's Manual page 557

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.
Troubleshooting
543