i dont have vontage, but i do know a thing or two about voip, its just like dsl on a computer, if its fast and you have no lag time your going to love it, but if you live in a area that has to many users dedicated to one connection its going to suck for you, the way to find out if your going to like voip or not is check your internet speed, slow internet speed will mean your going to have crappy voip experence. also keep in mind this technology is only a few years old. it will get better in the near future.