In September I'll be spending 3 weeks in the US and would like to bring my factory unlocked iPhone 4 (UK) with me. Since I'd like to make calls and send texts etc. using my iPhone while I'm there, I'd need your advice on what my options would be while I'm there? Is it possible to get some sort of pre-paid microSIM for my iPhone or any such thing for my 3-week stay? Thanks in advance.