Finally, in the 1990s, Internet Protocol-based videoconferencing became possible, and more efficient video compression technologies were developed, permitting desktop, or personal computer (PC)-based videoconferencing.
Videotelephony developed in parallel with conventional voice telephone systems from the mid-to-late 20th century.
Very expensive videoconferencing systems rapidly evolved throughout the 1980s and 1990s from proprietary equipment, software and network requirements to standards-based technologies that were available for anyone to purchase at a reasonable cost.
During this time, there was also research into other forms of digital video and audio communication.
Many of these technologies, such as the Media space, are not as widely used today as videoconferencing but were still an important area of research.
Such an antecedent usually consisted of two closed-circuit television systems connected via coax cable or radio.
An example of that was the German Reich Postzentralamt (post office) video telephone network serving Berlin and several German cities via coaxial cables between 19.
Although not as widely used in everyday communications as audio-only and text communication, useful applications include sign language transmission for deaf and speech-impaired people, distance education, telemedicine, and overcoming mobility issues.
It is also used in commercial and corporate settings to facilitate meetings and conferences, typically between parties that already have established relationships.
Telepresence may refer either to a high-quality videotelephony system (where the goal is to create the illusion that remote participants are in the same room) or to meetup technology which goes beyond video into robotics (such as moving around the room or physicially manipulating objects).