Buy multitudes of cellular phone minutes from Cricket Wireless. They are now in 29 states. Young, hungry and promotionally minded, I'm sure they will sell you lots of minutes and grow with you as well.
Mark up those minutes modestly, and then resell them within VoIP/cell packages with your own VoIP service.
Oh, and better yet, talk to Cricket about whether they have plans to enable WiFi or even some wireless broadband service. My sense is they may be already doing this. If not, find a partner.
(Just had an idea there ought to be a Match.com for tech companies-but hey that's another post).
And when that service pops out of the oven?
Bingo, (maybe even Boingo) Vonage. You're a triple-play provider.
Just like all your major cable and telecom competitors are.