I had found some posts like this:
http://voxilla.com/PNphpBB2-printvie...5-start-0.html
...which made me a little wary about going with an "unlimited" plan. I'm not sure. If you look at broadvoice's website, on all of the unlimited plans they have an asterisk (*), which denotes "unlimited plans are subject to significant limitations." I would guess that Vonage would be the same?