Did you try resetting the handset with the "9 # 9 # 9 * Hold" sequence?

Greetings, One of my Beocom 1 handsets won't register with the base. I did a reset, but no go. Going through the "secret" menus, I noticed the IPEI number was all zeroes. Firmware is 1.5. Any suggestions about what to do? Thanks so much. Best, Zenon