It's worth pointing out that traditionally P2P sharing apps such as Bittorrent, use TCP not UDP. So why would UDP cause VoIP apps to fail? Well for one huge reason, TCP allows for congestion control.
First, the article explains:
The article then adds:Gamers, VoIP and video conference users beware. The leading BitTorrent software authors have declared war on you - and any users wanting to wring high performance out of their networks... Upset about Bell Canada's system for allocating bandwidth fairly among internet users, the developers of the uTorrent P2P application have decided to make the UDP protocol the default transport protocol for file transfers.
Yikes! Say goodbye to VoIP. No more Skype. No more fring, Gizmo5, Packet8, Vonage, Bandwidth.com SIP trunks, and all the rest of my beloved VoIP applications and services. May you rest in peace my good friends. [sniff] Now I'll have to change my blog to the "Gadgets Blog".By most estimates, P2P accounts for close to half of internet traffic today. When this traffic is immune to congestion control [i.e. TCP], the remaining half will stumble along at roughly a quarter of the bandwidth it has available today: half the raw bandwidth, used with half efficiency, by 95% of internet users. Oops.
Game over man, game over!
Click above to hear this famous audio clip from Alien.