Wednesday, April 18, 2007
A videophone is a telephone which is able of both audio and video duplex transmission.AT&T conducted experiments and demonstrations of a "Picturephone" product and service in the early 1960s. Among the first manufacturers of commercially viable videophones was Toshiba.Videotelephony is frequently used in large corporate setups, and are supported by systems such as Cisco CallManager. Other companies such as Tandberg, Radvision, and Polycom also offer similar solutions. Videoconferencing has usually been limited to the h.323 protocol (notably Cisco's SCCP implementation is an exception), however newly a shift towards SIP implementations is seen. In accordance with the adoption of SIP telephony for home users, videotelephony is also slowly becoming available to home users.Another protocol using videophones is H.324; this allows videophones to work in regular phone lines, since the bandwidth is limited by the phone line. The quality is about fifteen Frames per second. This type of videophone is generally used because of the affordable price.Today the principles, if not the precise mechanisms of a videophone are employed by thousands of users world-wide in the form of webcam conferences using cheaply available webcams and microphones employed using software over the internet.
Posted by Best-Mature at 11:25 PM