I’m living in Iran and Apple does not provide direct support here. I had to factory reset my phone due to some problems and after that my sim card is not recognized any more. It seems (some service guy said) that the phone is locked to some operator abroad (I don’t know which, I don’t know how to find out, and I don’t know if knowing it can do any good). Anyway, I have no idea how it was working during past 4-5 years but I can no longer use it with any iranian operator. Does any one have a clue what to do?