As we head towards ISP rollout of VoIP services in Canada (ouch - $55 a month at Shaw?), it’s interesting to speculate about whether we are eventually going to see ISP’s port-blocking competitive VoIP services, like Vonage, etc.  I hope not - and without looking carefully at the issue I would speculate that given our market structure it could be considered anti-competitive - but port-blocking does seem to be popping up in the US now - via Om Malik, a report on US developments originally reported by Lawrence Lessig.