Hi, I am buying this for overseas use. I have an old INACTIVE t-mobile sim card lying around. I think that I successfully unlocked my iphone 3g (at&T) USA model that I just got. However, could someone tell me what should happen when i put in my old t-mobile sim card (about 3 years old). I see really nothing...it just says no service. Shouldn't it say "t-mobile" or something like that? What did I do wrong (if I did anything wrong) Thank you!