My internet connection is my home/office internet + my kids computer + xbox plus our voip phone.
The kids computer, our internet, and the xbox are used relatively lightly. And I have a quality of service router. The problem is, I still get choppy VOIP phone calls.
I just looked at my router and realized that I also have my secondary DNS on this connection (my main DNS is on my webserver, hosted elsewhere). When I looked at the active connections there was probably a couple hundred active DNS requests.
Could using my connection for secondary DNS be causing my choppy VOIP? I wouldn't think DNS uses much bandwidth, but I'm on a 5mbit line which means about 0.5mbit upload - perhaps not enough?
It is not only bandwidth usage which you should look at, but also packet priority. It could be that the small UDP packets for DNS are processed at high priority, causing your voip packets to delay.
You should look in the manual of your Internet router to see if it supports QoS (Quality of Service). If it does, there are options to give voip packets high priority and dedicated bandwidth resulting in high quality calls, Independent on the amount of other packets flowing to and from the Internet.