Verizon and ATT would probably buy into any group if it was cheap enough just on the outside chance it would matter in the future. Cost of buying the standards for themselves. Centurylink is a mismash of companies yet happy where they are at. Do enough small and large business to be happy and will follow most standards and leaders happilyhappily. They will figure out a way to profit.
Level3 and Bandwidth well not necessarily leaders but not a true follower. If it turns out to matter will make themselves known later. Just not self important enough to buy into any committee just because. Plus as long as they can go to a major manufacturer and buy equipment made to the new standard who cares.
Now why doesn't my small VOIP provider buy into this Ooma did. I see this as a failure on Future9 VOIP.ms Callcentric and all others who do not immediately buy into this and come up with a standard. Really time to move to Ooma even though missed out on the totally free deal.