If one company has emerged from the softswitch wars of the late 90s it is Sonus.
To be totally transparent I’m both a minor (very minor) shareholder and my agency has done some project work for them recently, but we’re not at this time and candidly they have really become the next gen carrier’s choice.
I know that Earthlink is using their technology as was AOL with the now dead TotalTalk. AT&T has some Sonus hardware/software in their network. For the most part all three provide/provided highly reliable service to me over cable modem, so when one looks for reasons why, one cannot look past Sonus.
I agree. Sonus has been a sleeper, but they really have a handle on the future. I did a pocast with Michael Rubin at Sonus just recently at http://www.realtime-unifiedcommunications.com/interviews/2007/04/realtime_unified_communication_18.htm and they’re defintely on the ball.