I almost want to pull my hair out..... I have a cisco 1760 router with a wic-1enet in slot1, a cisco 2950g-48-ei switch connect together. I implemented 2 vlans on the switch, vlan1 for data, vlan2 for voice. Also, I implemented NBAR Qos policies on the router, and I am sure it works good because when I make calls to the landline phone, I can tell from the monitor panel of cisco SDM, it did show the router reserves bandwidth for rtp traffic. Everything seems good except when I was trying to download a big file, I can hear jitter sound in the landline phone. Calls between extensions in the same switch environment are fine. Even though, the landline side hear the jitter sound when I was downloading, my side is clear. Does anyone have idea? Thanks.