I have been using T-mobile prepaid for a while now with an iPhone 4, but it only has minutes/texts with no mobile internet. I have read that buying an E71 from Walmart and switching sims would work for an iPhone, but I cannot find any specific details. Does this method still work? Is it 3G speed? What are the plan details exactly? $45/mo? Basically, I just want a detailed description of what needs to be done before I spend $250 on the E71. Has anybody had any problems? Thanks.