Resurrecting this old thread as I was searching for an answer. I lost my IMEI code when attempting to use this app, the phone is Samsung Galaxy S locked to Orange (EE) in the UK.
Restoring the EFS files the app made reinstated the IMEI number correctly, but obviously still stuck on Orange. Tried a couple of times no dice.
If you do have an I777, then use the app "GalaxSimUnlock" from the market. It's free here on XDA.
I777(S2)
Captivating M3
UCLE5
AJK 1.49