That's not a UK phone number. It's a premium rate international call forwarding number. You dial a UK number but are being billed up to £50 for your call to be transferred to any phone anywhere in the world with no way to find out to which number or even which country your call has been transferred, and no way to know how much you are being billed for the call until you get your next phone bill. No legitimate UK business uses +4470 numbers - these are almost always the sign of a Nigerian scam