I've been doing a lot of reading about VoIP during the past year and looking at Vonage in detail, it clearly states on their web site (not even hidden contracts) that calls to 911 is an additional cost to clients' services. Moreover, Vonage always stresses the importance of having such access.
However, I see the problem in people not being familiar with VoIP and how it works. I've read a huge research done for AT&T a couple of months ago. The majority of folks still don't have a clue what VoIP is or what it stands for - many heard it for the first time. Also, even those who are familiar with the service, are forgetting that there is Internet backbone behind VoIP. Just like cellular connectivity, 911 calls have to be paid for (federal law on mobile/internet communication carriers, thus its quite amusing to see state sue the company). Its pure economics - government establishes tax on companies, which is moved to consumers.
Its right on their web site and sales reps always stress it on the phone as well - 911 calls are an extra and it is highly recommended to have. I'm sincere about the situation, I hate seeing people hurt, but why ignore something of such importance just to save a couple of bucks?
Best,