[novie]

I've used that service and found it worked quite well, it picks up whatever network has the strongest signal wherever you might land(something i wish i could see all the time domestically lol). Depending on your purpose there are pros and cons. Good things include: no cost except when used and number is yours permanently (after getting the free SIM card to swap into the quad band GSM phone you hopefully have). Works pretty much everywhere but Korea/Japan. Good as well is that you won't get calls from people that don't know you're not stateside. Because you will be using a UK number, it may be a cost for someone stateside to call you unless they are using voip or something. But it can be nice for calling home and especially for making in country calls. You'd have to check the rates for your domestic carrier to see how it compares where you are going - typically you must let them know you will travel overseas and may put you on a service for it, but they may be cheaper for calling home to the US, though perhaps not for calling in country or to a third country. Also receive text messages for free which is nice as you will want to turn off voice mail rather than be charged for the time.