You'll need to setup QOS on your router and make sure any switches you have between the router and the obi202 will see the QOS tags and respond accordingly. I could tell you how to do this on Cisco routers, but hell if I can figure it out on most others. I'm still stumped by the QOS settings on the Verizon FiOS routers.
Also use a test like this one to check the quality of your line, specifically for aspects effecting VOIP.
http://www.ringcentral.com/support/qos.htmlBTW, when setup and used properly, QOS, which typically is a layer 3 protocol, is a very robust part of the TCP/IP stack.