I bought an used iPhone 4S At&t and unlocked it through one of those eBay seller a month ago. I restored the iPhone 4S through the iTunes software and it tells me Congratulations my my iPhone is unlocked. I installed a Tmobile micro SIM card in the iPhone, it searches for a signal and then it shows the dreadful No Service. When I change the settings from auto signal checker to manual, the Tmobile 3G is in the list that can be selected but still No Service. Last resort, I upgraded the firmware to 6.1 and jailbroke the iPhone 4S with the Evasi0n but it is still showing the big fat No Service message. Everything works flawless except the phone feature. Did I just bought an expensive iPod touch? Oh I also bought those Gevey S SIM card and that didn't work.