Yes, but you will have to do a "Firmware restore" first.

Follow the steps below to do a firmware restore.

  1. Remove power from the unit.
  2. Hold the MENU/settings-button (middle button on top row) during while you power on the unit.
  3. Keep holding the button until you see the "Recovery menu" in the display, then you can release the button.
  4. Select option 3 (by pressing digit 3) "Firmware restore".
  5. Let the unit restore factory firmware it could take up to 3 minutes.
  6. After the process is done, the unit will reboot with factory firmware.

(same for Konftel 300IP and Konftel 300IPx)