I have a three cabinet DXP Plus with static on the 2 T1's on Cab 1 and Cab 2. This static or clicking only occurs on the T1 incoming/outgoing calls. I have changed the cards and still static. There is no static when calling station to station or checking voicemail. The T1 circuits have worked fine for over 7 years. They did change vendors. After changing vendor, it worked fine for a period of time. Then I got a call regarding the static. It sounds like static or a clicking when accessed. The vendor checked the circuits and said everything is good. I asked if they did any upgrades or changes to the T1 and they said no. So now trying to figure why static clicking only occurs on the 2 T1's. I did turn off cabinets 2 and 3 and check the cab 1 T1 and no change. I also removed the T1 card on cabinet 2 no change. Any suggestions? No program changes have been made to the DXP.