Will I be able to use an unlocked AT&T iPhone 3GS with European carriers? Moving to Austria in two weeks. I have an iPhone 3GS that has been unlocked by AT&amp;T.

Will I be able to use my iPhone 3GS with European carrier sim cards once I get there?
Yes, having taken an unlocked American AT&amp;T iPhone 3GS to Britain and Germany, I can confirm that you can just put in a European SIM card and it will work. Much cheaper there than here too!