How Would You Compare Vocalocity With Vonage?

I have helped a few offices with Vocalocity services.  They are a fair service and they are a good choice for small offices of up to maybe 20 users.  That said, it has been my experience that their support folks are not too eager to get in to helping you diagnose what could be wrong and resolving the issues.  Case in point is the quality of service.  Yes, you can have the QoS settings on your network equipment in place but if you have, say, 8 people on the phone and each is also using a computer, you need to have sufficient bandwidth.  Most small offices will only have maybe 10 Mbps download and 1 Mbps upload for internet services.  That is not not enough to support a good quality of service for that data for calls and computers.  Vocalocity does have support pages that explain some of this, but they are not easy to locate and, again, when I have questioned their support folks, I have expressed call loss, latency, calls where there is no sound on one end, etc. and have not yet had anyone from their team suggest that my bandwidth may be too low.

I think  they are a decent player in the game and they have some good advantages over other providers.  Just beware that VoIP is still one that needs to be understood by your IT person so you don't experience frustrations once you sign up.