I have an old iPhone3GS given to me by a friend. It was jailbroken previously, but has been officially unlocked in AT&T's system. I have factory restored it (plugged into computer while holding the button) but it won't see my T-Mobile SIM card. It just says, no SIM card is installed. After browsing the web for a while I read somewhere if it was jailbroken it can permanently mess with the phone. Is that true? Is that why it won't recognize the SIM? If I got a hold of a AT&T SIM card would that make a difference? My friend gave his brother his iPhone4, also unlocked, and it worked just fine. His brother is using it on T-Mobile.
Any ideas?
Any ideas?