We are using phone booth with t28 yea link phones. I have Comcast with 4 different yea link phones. All computer and phones are on same linkage srv4000 router. We have a clicking on the line and word clipping. I have taken the phone and plugged it directly right into the Comcast router and there was still a problem. I took the phone to my home with fios and did not experiience clicking and word clipping. I have heard about qos. Any suggestions.