i bought an iphone and let my friend borrow it so he could jailbreak it and unlock it to use it on tmobile but he couldn't do it, but when i put in my at&t sim card it doesn't read it, it just has 5 dots where the bars should be. I think all i have to do left is install the yellowsnow application from cydia but it won't let me connect to it via wifi either somebody please help me