I tried flashing to PR1.2 Global firmware but still locked... I'm looking for a while a way to enter the code and found other peoples with the same problem but no results so far. Some didn't had their phones locked even if bought from Vodafone UK, other asked Vodafone to unlock their phones and they received an unlock code with the following instructions:

1. Power on your Nokia N900
2. Type #pw+UNLOCKCODE+1# (Where UNLOCKCODE is your Nokia N900’s unlock code)
3. Your N900 should say “SIM Restriction Off”

but again, no way to do it because of the "w"

optimistprime code was entered correctly, I bought it from ebay from a member who also sold some some codes for some HTCs and a SE X10 and worked flawlessly