Common symptoms of incorrect Quality of Service settings on your network tend to be choppy video/audio. You will in most cases see break up in video and audio. It will happen during times, were the internet is being utilized the most on your network. The computers are using the internet and there is not enough consistent bandwidth for your phone calls and/or video conference.

If you have a complex network, Quality of Service can be your savior or your undoing. I could certainly go over a whole bunch of commands on how to configure Cisco routers through a terminal. Unfortunately, that is not going to happen in this section. You would be reading for a month. Plus, it would just take up way to much of my time. If you have some knowledge on how to configure routers, you may be able to get things going. Use the web interface that is built into just about every router out there, these days. The Cisco SDM is great for getting a basic QOS setup going for you. Plus, it can accomplish what you need with little understanding of the subject.

Your best bet otherwise is to start taking classes. Classes to become a Cisco Certified Network Professional will cover this topic completely. If you don't want to take classes, it is also possible that you may be able to get away with going out and buying the Cisco Press CCNP study guide box set. After reading the book for CCNA and the book for CCNP-ONT. You should be able to go back and setup your network using the book as your reference manual.

Finally as always, if you have this problem and you want to simply ask me what to do. Take the time, sign up at the hire a geek section and ask your questions. I should be able to provide you with the assistance you need.