A final gotcha, I had a locked prepaid phone that the carrier, AT&T tried to unlock. (From memory) The first 3 codes did not work. You only got 5 tries and it was locked forever. They referred me to Nokia (conference call) who tried another code that also failed. I stopped short of going for the 5th just in case. I only ever used it for travelling in the USA so staying locked to AT&T was not a big problem, just a few extra dollars and it prohibited me from using it as a spare here. A few years later 2G was closed so it was not even a capable paperweight.