I had Vonage for about a year. I liked the service a great deal, and the features such as e-mail and web access to voicemail messages, setting up your own call forwarding, and the online viewing of phone logs was awesome. The idea that I could take the VOIP adapter to any broadband connection on earth, and after 30 seconds to re-register itself with Vonage's servers, the phone would ring with my "home" number if it were called, was cool.
The biggest plus was not giving my local baby bell any of my money.
We only discontinued the service because my wife and I had lived for a year + as "cellular only" users, and even at the cheap price for Vonage, we hardly ever used it. We always have our cell phones in our pockets, and have lots of airtime, and many of our family and friends are on the same carrier, giving us even more free calling.
With the majority of people using cordless phones, they won't work in a power outage anyway. We didn't even have a corded phone that would work off of the phone line voltage alone as a backup.
However, if you are concerned about 911 service, here's a little secret neither Vonage or the local "Bell" will tell you. Even if your outside line is "dead" with no dial tone, but as long as it's got a physical connection to the phone company, 911 will still work. It's required by law that the telco switches will still take a 911 call on any line. The telco won't advertise this fact as they want people to subscribe, and Vonage won't mention this as a "backup strategy" because they don't want to point out the weaknesses in 911 with VOIP. (Which admittedly are being fixed quickly in most areas.)
So if you're a VOIP or just a Cell-only type of phone user, get yourself a "red phone" and leave it connected to one jack that is wired to the outside phone line for 911 dialing only. Keep a sharp eye out for a "legitamate" emergency nearby like a fender bender, a reckless driver, threatening stray dog etc, so you have way to test. That way you have confidence that it will work for "your" emergency.
