I hate to say this but AT&T's Call Vantage is actually VERY good! I tried Vonage last year and had a lot of quality of service issues. Dove in again when AT&T CallVantage came available because, unlike Vonage, i had no out of pocket expense to start upwith them ( i lost about 70 bucks on the vonage thing after a 3 week trial)
The service is great, their web page manager is excellent and I am VERY VERY pleased with it!.Until 5/31 you can get the first six months for 20 bucks and after that it's 40 a month ( a little more than Vonage) but it is UNLIMITED calling.
Check it out, and quickly! if it's available it's your best shot.
Sorahl