The telecommunications line is usually leased only for the lecture period. There exists almost no interaction between students at various remote sites. There is also a need for robust backup plans in case the telecommunications lines fail. Resources are available on the Internet that will help overcome some these limitations. Teaching using IVN is a different experience for instructors.
Instructors have to familiarize themselves with the technology in addition to the course material.
Some instructors find the technology to be intimidating. Teaching a distance education course requires a lot of advance planning on the part of the instructor. Design of the course, presentation styles, physical appearance of the instructor etc. Research in the learning theory area provides guidance on these issues. The Internet is a network of networks that links thousands of computers all over the world.