Panasonic UDT131: Factory Reset the Handset
A factory reset is a "last resort" in your troubleshooting; it is a master reset to restore the device to its original system state by erasing all of the information stored on the device in an attempt to restore the device's software to its original manufacturer settings.
WARNING: A factory reset will delete all user saved information, such as contacts in Phonebook. Please do NOT factory reset your device unless expressly asked to by a support engineer.
How to Factory Reset a Panasonic UDT131
NOTE: This resets the HANDSET only, NOT the base!
- Power off the handset
- Power on the handset
- When the display appears white, press and hold the [TALK] button for 10 seconds and then release it
- Press and release the left [Softkey]. Then dial  on the key pad
- You will see Maintenance Mode on the display. Press [OK]
- Select [Reset Handset] then select [Yes]
- Power off the handset and power it back on. Handset will be factory reset