We are running 3CX v15 PRO. A couple of our windows client users are experiencing mic feed back to the headset so when they talk they can hear themselves. Exactly the same as if you put your mic into Listen to device mode. This is only happening intermittently and to incoming calls. I have heard the source audio from our ISDN gateway and also asked the user to record the conversation and the audio is perfect, no feedback or echo as they user calls it. So this leads me to believe that the mic audio stream is being fed back to the earpiece of the headset. We are running the latest 3CX Windows client with Plantronics Hub 3.9.0. and on Windows 7 Pro. Does anyone know why the mic audio stream is being fed back to the Plantronics earpiece? Thanks in advance.