I don't think I've ever done any sort of per-minute payment for home calls (up to 1.44 cents/min for most outbound domestic calls), and that certainly isn't the norm for the US, but in this case it potentially saves me quite a bit. For 4 lines and 1 virtual number, what I pay Vonage works out to be around $95/month. So far, my usage with them has peaked at 782 minutes in a single month. Worst case, that would come out to $32.13 (20.87 monthly + 11.26 usage) with Vitelity. It would probably be even less than that, considering Vitelity rounds call times in 6-second intervals, rather than to the next full minute like Vonage.
I did have to add yet another service to the mix to get everything working... www.cnam.info, which does caller ID name lookup for US and Canada numbers. Vitelity claims to have that service, but I could never get it to work. It costs $.05/lookup, with a minimum of $2.50/month, but considering the savings stated above I'm certainly not complaining.