Originally Posted by
star_world
512kbps would be more than enough in theory. In practice, what is more relevant is how the traffic is prioritised, so that other (non-VoIP traffic) cannot flood the available capacity and cause the quality to drop dramatically.
What sort of router are you using?
A G.711uLaw call (the basic highest bandwidth version of VoIP you'll get) consumes ~80Kbit. A G.729a call (the lowest bandwidth version you'll get) consumes ~32Kbit.
And while traffic priority/QoS is important it is also important to know that there really is no such thing on the internet. On a private network you can configure the infrastructure to prioritize the voice traffic and drop other packets if the lines get full. On the internet you have zero control of such things and you are stuck with a best-effort solution. That means that you are, for the most part, just going to have to deal with whatever you get in quality.