How do I perform a complete reset (to factory settings) for a COMfortel M-5X0?
Press the Off key for a long time to switch off the handset.
Press and hold down keys 1, 4, 7 and the On key at the same time to switch it on.
The handset starts operating, and displays its Service menu. You can then enter the key combination 76200.
Select the Handset Reset menu option and press OK to confirm.
The handset reboots with factory settings.