Reset 7912 phone to factory defaults

Hi there

I'm interested in resetting a 7912 phone to factory defaults. I reboot and restart and reset but everytime it comes back there's this annoying 123 extension.

I'd like to wipe it all and then get a new load off the TFTP server.

All the settings are ok and it's been installed correctly into call manager phone configuration.

Any help will me much appreciated.

Thanks

paul