While there's a surcharge when dialing from within the UK, I don't think there's a premium from the States.
I guess you know something that all those businesses who provide geographic numbers for their international customers don't. For the OP, check with your long distance carrier on the cost before making the call, if you need to.
Anyway, if that's the case I'm going to start routing all my 0870 calls through the U.S. as I can call the U.S. for free, and can call the UK from the U.S. for a very low cost.
