said by zomaxx :
How do you know if it has Qos features
You'd have to read the user guide for the specific router. Some routers let you give priority to protocols. You'd be looking for "RTP."
I prefer Tomato because you can specify more advanced QoS rules, such as the IP address. I've heard that if the router has to examine packets to determine what they are, it slows the router down. So, I thought Tomato's IP address was better.
For the "which router is best" question, you should go to www.linksysinfo.org . There is a Tomato forum there.