Video and audio communication over LAN

The main goal of today's computer communication is to be as close as possible to real human communication, where media such as voice, image and gesture should be accurately simulated by the available computer technology. People and computers are placed in a time and space continuum. Two or more people may coincide in one or other of these dimensions, in both, or in neither. During a "live conversation", time and place are the same for two or more communicating pratners. If one of the conversation partners stores and then forwards his message (as in Email), then for the other partners the time is later, place may be different and hence the live or real-time characteristics of the conversation are lost. The concept of peopleat distant locations communicating with each other both visually and verbally over a telephon line (otherwise known as videoconferencing) has become reality in meeting rooms and on desktops. Videoconferencing has been technically possible for years, but at such great costs that it was a practical alternative for only large organisations with specially designed facilities (Bellcore, NTT, Xerox).