The "we have corrupted your PC call this # or else" bit

Can someone explain this.......why hasn't someone got this # down, first get hold of the police (FBI, whoever), go call the #, and have it traced? Or is it like web sites, they can move to another # so easily that it'd be chasing their tail? I'm just amazed this ever works.

via International Skeptics Forum http://ift.tt/1j1i4XD