I have no idea if I can use my iPhone in the US.
I live in Taiwan and bought the phone there. I'm going to stay in US for a while and I bought a pre-paid sim card for myself. It starts for one month the second I put it in my phone, so I can't test it beforehand. Can anyone teach me how to find out if a iPhone is unlocked or not? I guess it probably isn't, so how can I unlock it?