So the the thing is that one of my friends had an iphone and his sim got locked so he gave it to his other friend and he lost the sim card since it was worthless to him he sold it to me for a $100 dollars. The thing is i use tmobile and i wanna unlock it to put my use my current sim card with it. But when i put my sim card in it still doesnt take me into the homescreen when i slide the slider it takes me to emergency dialer. So i was thinking is there a way to unlock my phone using my computer or an other way without an at&t sim card? Cuz without any sim card it just says No SIM card Installed: Insert a Valid SIM with no PIN Lock to Activate Iphone. And if there isnt a way how much would it cost to get an at&t sim card with no plan on it? I just want to try it the way that would cost me from least amount of money and i dont mind how complicated it is.