Nokia E7 & N8 Pentaband 3G Works with AT&T, T-Mobile & in Europe

If you take, for example, an AT&T iPhone 4, jailbreak it, unlock it, and put a T-Mobile SIM card in it (which you would have to shave down to fit in the iPhone 4’s micro-SIM slot), you would find that you could make voice calls but wireless data would be limited to slow EDGE network speeds. The reason is that while most of the world has standardized its 3G frequencies, AT&T and T-Mobile use different 3G frequencies from each other.