Eric Dahl at PC World:
The Buzz: If you can’t beat ‘em, block ‘em. Increasing competition from Internet phone providers like Vonage and from services such as Skype is causing traditional telephone carriers around the world to look at methods to slow or stop IP-based calls that cross their networks. The key technology, from a firm called Narus, can detect VoIP packets and either block them or deprioritize them to reduce call quality. A number of foreign telephone carriers have already enlisted the company’s services.
Bottom Line: Domestic telcos are legally prohibited from completely blocking competing VoIP services, but there’s no rule against prioritizing other traffic. And filtering software could put a serious damper on international-call savings if more countries begin to say nein to VoIP.
VoIP packets have a standardized format so they are easy to “adjust.” If this sort of thing really becomes widespread, I would guess that VoIP packets will soon be wearing camouflage.