I'm tempted to switch our landline over after learning Vonage only eats up 96kbps of your upstream (we have 768k up, so plenty to go around).
I'm really concerned though by the apparent need to forward 10,000 UDP ports to the Vonage VoIP device. That seems a rather sloppy and cludgy way to implement it. We only have one public IP at this time, and I'd rather leave the Vonage device behind the firewall so that the web interface is accessible. I really don't understand why they couldn't reduce the number of ports and use UPnP to report to the router which ports it's using at any given time.
The other concern is faxes. We probably use that about once a year, but I'd rather not lose that ability.
Anyone have any opinions or experience with it?
[Edit: Also thinking about using the VTtech IP8100 with it.]