I'm using an unlocked iPhone 4 that I brought from Europe and I've been using it on AT&T for over a year, contract free. I used the loophole last year to get unlimited data and it's been working flawlessly ever since. Now, I have the opportunity to get an unlocked iPhone 4S from Europe, again. If I just pop in the AT&T SIM card, will I get the faster 3G, or "4G" as they call it? Thanks.