As it says on
the site for the number you quoted:
Quote:The service works because when you dialed our numbers, your telephone operator has to pass part of the call charges to us as part of UK telecom interconnection agreement. We use the money we receive to fund calls to the listed destinations.
If you were to use an 01 or 02 number instead of the 0870 number, then the company would not receive any money for funding the international call! In other words, it is extremely unlikely that there is an alternative geographic number available for this service.
This is in fact a 'legitimate' use of an 0870 number (altho' it would still be preferable to use an 09 number at the same rate), where the call cost is shared with the company in order to provide a real service.
Or do you expect them to forward your call to an international destination free of charge??