Got a question about using UK Pre-Paid SIM Cards and data setup. My parents, who are not very tech savy, are heading for the UK. They will be there for three weeks. My Mom has an iPhone 3GS which I just had AT&T unlock. As soon as they arrive, they plan to get a pre-paid SIM card to use for in country calling and for data while traveling. Question is this: Would they need to do any carrier specific settings to get data working? I've recommended they get a T-Mobile SIM since T-Mobile seemed to have the best data rates. Thanks!