Just come back from a holiday in Florida. Four of us with Smarty sim cards had NO service at all. A large number of emails were exchanged trying to resolve the problem, but to no avail. I'd even spent £35.00 on my phone and £10.00 on my wife's phone on out of plan specifically to cover use in the USA.. Most of the £35.00 was taken up in responding to the many emails between myself and Smarty. The annoying thing was that those of the party had other carriers (Vodaphone, O2, EE) NONE of them had connection problems. The problem has still not been resolved as far as I am aware. So, if you are going to the States, beware of possible problems (unless you already have the solution)!