my voip services, and we use 2-3 a day depending, are not really using more than 128kps or so OUTBOUND each. So, with the 750kps pip up we have, it works fine.

I DO use QOS on a linksys router, with the open source tomato software installed so I can PRIORITIZE any of the VOIP adaptors or protocols (skype is the third VOIP we use) above all other data traffic.

Since the INBOUND BW is 6MB, I don't alter the inbound (which is actually hard to do with QOS) so that the inbound VOIP has reserved bandwidth. But, it really hasn't ever been a problem unless a large download is going on.

With the buffalo, you MIGHT be able to change the software to a dd-wrt or tomato, which would allow you to setup QOS for VOIP properly.

Or, you could put ANOTHER router in the middle (they are pretty cheap, I just bought a refurb netgear for this) in between your modem and the buffalo.

I have no problems with conflict or call quality with three calls running in parallel.