Sorry I don't use iphones much. But anyways here are some questions I have to ask. If I jailbreak and unlock an iPhone 3G, can I insert my at&t sim and use it to make calls/text/internet? Will this also work for the 3GS? Also, can I put a T-Mobile sim into the unlocked iPhone 3G? Finally, can I use EDGE or 3G on an iPhone without having a sim in it?