I have had Vonage for over 5 months now with a hicup when I first tried to hook it up. I bought an adapter from a large box store and had to return it because it was DOA. I asked Vonage which adapter was the lease troublesome and they said the Motorola V1000. I went searching for one and got the last one available at Radio Shack. No problems here but make sure you try out the Vonage speed test
http://www.vonage-forum.com/voip-speed-test.html
to check your dsl.
Porting your old number can be a nightmare for some folks to Vonage. I only had to wait the 20 days and it was switched over but others have had 8 month waits!
Enhanced 911 will soon be available on VOIP according to the FCC chairman.
Can you get "Naked DSL" with verizon? (no working number just dsl?)
I reccomed that you go to the Vonage forums http://www.vonage-forum.com/forums.html and read thru the posts there. Keep in mind those posters are usually the ones having problems and you don't see too many positive posts.
I am saving over $50 per month not having Qwest and AT&T (my long distance) and only 1 outage (2hours) that I know of. Line quality depends alot on your broadband connection. There customer service is getting better from what I have read.
youneverknow