Greed over technology.

Are you trying to control QoS between two endpoints over the public Internet? If so, tagging the voice traffic leaving your router isn't going to do much good since once you hit the rest of the Internet the other routers on the trip to your destination will immediately disregard any QoS settings that your router has set. Otherwise we'd have boneheads sitting at home configuring their routers to send all their gaming or P2P download traffic with voice level priority. You currently can't control QoS over the public Internet.