VoIP Users Only? (Score 3, Interesting)

The Thread suggests that this will be a problem for VoIP users only; but it seems to me that the overseas callcenters will call whoever they want regardless of what type of carrier the call-recepient uses. I don't think it is less expensive for them to call another VoIP line than it is for them to call a land-line or cell phone, but maybe I'm wrong.

Another thing... Is there a way that VoIP numbers are indexed or listed? Is there such thing as a listed or unlisted VoIP line?