someone help me? My friend gave me his iphone because he switched from cingular to t mobile. since i have cingular i put my sim card into the i phone but the i phone still wont work. im wondering if there is a way for me to unlock my iphone so i can use my cingular sim card in it, or do i just have to go to the apple store for them to register it for me? but i know that there are many ways to make the iphone work...