I have one of the D-Link wireless routers that has the Stream Engine on it, and I never could get it to work reliably. How I tested was to download a giant file while talking on the phone. Downloads were usually OK, no break ups or anything like that on VOIP. However, uploads were always causing problems with choppy voice. If I uploaded a large file, the VOIP choppiness would make the call unintelligible. I played a lot with settings but never got the upstream/choppiness figured out.

I have since moved to Tomato on a WRT54G and it is perfect. I have finally tweaked the downstream and upstream settings and get no chop regardless of my download/upload rates. I also ran PFSense which worked OK. DD-WRT I never could get set as good as my Tomato!

Scott