Searched and couldn't find the answer to this. My friend unknowingly bought an overseas iphone, and now she is trying to make it work here in the U.S. The apple store told her she needs to unlock it, so I'm assuming all I need to do is unlock it and put the ATT sim card in and that's it? Shouldn't it work automatically since she's trying to use ATT? Also, will everything work fine like 3G and wifi? Thanks in advance