1. Introduction

The telephone was the predecessor of modern visual communications. But also the telephone technology met challenges when it was introduced in the latter 19th century:

Figure 1. Picture phone, 1964.

"This 'telephone' has too many shortcomings to be seriously considered as a means of communication. The device is inherently of no value to us." Western Union internal memo (1876).

The next important development happened in the early sixties, when the picture phone was introduced

Since 1990 the development has accelerated, with frequent refinements of communication protocols and standards:

• H.261 (1990) – a new communication protocol that improved compression of sound and picture substantially.
• H.263 (1996) – a refinement of the previous protocol.
• H.264 (2003) – a "revolution", which doubled the quality on low bandwidths.

This development has implied that video conferences today are of a technical quality which is comparable to, but not completely equal to, TV quality.

As a consequence of improved technical quality and the extent of broadband networks, we can see that areas of usage of visual communications increase. During the last years video conferences are being used not only in traditional meetings, but also in distance learning activities and many other applications as well.

Figure 2. Visual communications of today are of technical good quality.