Videotelephony

Videotelephony, also known as videoconferencing, video calling, or telepresence, is the use of audio and video for simultaneous two-way communication.

Videophones were standalone devices for video calling (compare Telephone). As smartphones and computers have become capable of video calling, the demand for a separate category of videophones has disappeared.

Videoconferencing implies group communication and is used in telepresence, the goal of which is to create the illusion that remote participants are in the same room.

The concept of videotelephony was conceived in the late 19th century, and versions were demonstrated to the public starting in the 1930s. In April, 1930, reporters gathered at AT&T corporate headquarters on Broadway in New York City for the first public demonstration of two-way video telephony. The event linked the headquarters building with a Bell laboratories building on West Street. Early demonstrations were installed at booths in post offices and shown at world expositions. AT&T demonstrated Picturephone at the 1964 World’s Fair in New York City. In 1970, AT&T launched Picturephone as the first commercial personal videotelephone system. In addition to videophones, there existed image phones which exchanged still images between units every few seconds over conventional telephone lines. The development of advanced video codecs, more powerful CPUs, and high-bandwidth Internet service in the early 2000s allowed the new category of smartphones to provide high-quality low-cost color service between users almost anywhere in the world, eliminating the videophone as a separate product concept.

Applications of videotelephony include sign language transmission for deaf and speech-impaired people, distance education, telemedicine, and overcoming mobility issues. News media organizations have used videotelephony for broadcasting.