Old Tricks, New Implementation, That's All
Hey, personally I am not too worried about this. You can do everything this service offers with the right voip account (cheaper too) and some inexpensive or even free (Asterisk PBX) software. Any criminal intent on this kind of deception is already doing it and has probably been doing it for at least 4 years.
The service is too expensive for any tom, dick or harry using it as a serious money making tool. As stated, you can do this much cheaper with a wee bit of googling and a couple of hours on your hands.
All I see this service being used for is the "Hey, i've just murdered your family and stolen their house! Only Joking!!!" kind of gag!
Don't worry people. Anybody who reads Reg has at least enough common sense to know when they are probably being duped. If anyone rings asking for your credit card details, regardless of what number it comes from tell them to bog off! Caller ID is no proof that the call is genuine and never should be used that way!
One thing I will warn though is: PINS on your mobile phone voicemail systems as some do use caller ID to verify the subscriber, but we all have PINS set already! Right??