Cablevision is the fastest “facilities-based” (ruphemism for companies that own their own infrastructure) VoIP service and is adding 1,000 new customers per day. I think even Vonage is adding more than 1000 new customers a day. Cablevision says that the company has surpassed the 250,000-customer milestone.
Recently FCC ruled that “nomadic” VoIP services are interstate in nature. I suspect that “facilities based” service providers (meaning one has to use their access network to get the service) are not nomadic. So they have to follow local and state regulations and by implications they have access to PSAP and such. This will help them in the PR campaign to distinguish themselves against other VoIp providers and to place them on par with the incumbents.