I have the same problem, there is some strange delay transfering calls and I think this delay growing up using the server. When you restart, it seem all be normal, but deley is increasing slowly hour after hour. When the extension hang up, there is some seconds before the comunication starts and can hier the other side. In some case, when the extension hang up, the phone stil ringing (1s more) and then cominication starts. From the call side I see that the distination extension hang up, but I hear ringing in the phone.