Certainly there are numerous VoIP Providers out there. Many that offer retail service and just as many that offer wholesale services with some offering both. VZ is now pushing the MCI Wholesale VoIP service including a new feature (virtual NXX). VZ won't call it Virtual NXX because it has been fighting CLEC's like GlobalNAP over this for a couple of years. So VZ calls it Foreign Telephone Number Assignment (FTNA). Any how!
Telephony mag has an article about Momentum Telecom in Alabama, a former UNE-P CLEC that now offers Wholesale VoIP. Why not retail? " The cost of customer acquisition could rapidly jettison a business case.... Alan Creighton, president and CEO of Momentum. says, “The cost of customer acquisition was just too high.”
That's as realistic a view as I have seen in telecom in a while. I figure the others are in it for the short haul and are just trying to rake in some dough before moving on to the next thing.
Most of your VoIP Providers are far removed from the actual engine that is the phone platform. Most buy minutes and DID's from resellers, who in turn buy them from someone else. No network. Just an Asterisk box or two -- or for the shining examples a Broadsoft, Sonus or Sylantro softswitch -- at a data center where you cross-connect to bandwidth, minutes, maybe the VPF or ENUM. Outsourcing the network and services removes the provider from being able to manage or control the quality.