I can tell you that 0870 prefixed numbers do work (sometimes) from overseas. The rate charged seems to be variable. I can call from the US using a 'pre-paid' service and local number for 3c / minute (and remember, I don't pay for access - 'free' local calls!) which is about 1.7p / minute. However, I have heard from a friend in Australia that he was charged $AU6.00 / minute for a 0870 call to the UK, and was told by his provider that these were' premium rate calls'. BTW, $6.00 is about 2.00 pounds a minute!

However, I have to be concerned about the low US rate. It may be that the provider in the US doesn't get enough 0870 calls from American subscribers to realise the premium cost - and when or if they do, the rates will rocket upwards!