I am having trouble with ISDN calls through a VTC in one of my rooms. If I dial ISDN from room to room through the PBX, all works fine. When I dial through the outside world to my other room, one room has picture and audio and the other just has audio. After a couple of seconds it starts to speed down and drops the call. And vise versa if I dial back from the other room. I'm not sure if I'm in the right forum for this question or not? Anyone have any suggestions or know whats going on?