One of our users is able to make calls internally and externally without any problem. The problem arises when someone dials their extension: no popup and ringing sound occurs on oncoming calls. We have tried setting the ringing device to Sigma Tel Audio and primary sound driver and experimented with popup window settings.. This computer has Windows XP professional, the VOIP Client is 6.0.610.0 like the other computers in our network. However, the computer having trouble uses a USB web camera with built-in microphone and headset to make and to receive calls thru 3CX soft phone. Hopefully, someone has had a similar problem or knows the solution to this problem.