The most common problem with VCN was the failure of some students to speak loudly enough. The microphones simply did not pick up students remarks which were made at normal levels. Even though I was never quite able to solve the problem, I had some success at getting students to speak louder by using a peculiar technique.
Early in the semester, I originated the class at CGCC rather than GCC. Before class, I arranged with one of the CGCC students to mumble a question to me in a low voice. Naturally none of the students at GCC heard the question. I then remarked in a clear, loud voice: "that is a very good point Bob Ñ certainly if you do not understand it, there is little chance of getting any grade higher than a 'C' on the next exam." I then started in on the lecture before anyone had a chance to say anything further. The response from the students at GCC was predictable.
This leads me to the last point Ñ and it is an important one. If you teach a VCN course, be sure to originate at least one class at each of of the remote sites early in the semester. The students at the remote site will appreciate the visit and the students at the originating site will have a chance to see what its like on the other end of the microwave and telephone links.