How do you reset a Yealink IP Phone to factory default settings?

Method 1: Via web interface.
  1. Login in the web UI of the phone
  2. Go to Settings → Upgrade page, select Reset to Factory Settings
  3. Press OK to continue, press Cancel to quit.
Method 2: Via phone menu.
  1. Press Menu Softkey.
  2. Go to Settings → Advanced UI, enter the password to continue.
    Select Reset to Factory option.
  3. The LCD screen will prompt you with: “Warning, Reset to Factory Setting”. Press OK to continue.
Method 3: Hard reset on the device

Press and hold the “OK” button for about 20 seconds.

Note: The phone can take a few minutes to reset to factory default settings. Ensure that the device does not lose power during this time or it may cause damage to the phone’s software.