In 1955, Gregorio Y. Zara, a Filipino engineer and a graduate from the Massachusetts Institute of Technology, invented the first videophone, known as the "photo phone signal separator network."
Meanwhile, AT&T conducted experiments and demonstrations of a Picturephone product and service in the early 1960s, including at the 1964 New York World's Fair. The demo unit was usually in a small oval cabinet on a swivel stand, intended to stand on a desk. Videophones, possibly AT&T units, were featured at the Telephone Association of Canada Pavilion (The 'Bell' Pavilion) at Expo 67, an International World's Fair held in Montreal, Canada in 1967. Several demonstration videophone units were available for the Fair-going public to try, who were permitted to make live video calls to recipient volunteers in the United States. Color was not employed. The equipment packaged a Plumbicon camera and a small CRT display in the cabinet. The camera was located atop the screen, to help users see eye to eye.
Video bandwidth was 1 MHz with vertical scan rate of 30 Hz, horizontal scan rate of 8 kHz, and about 250 visible scan lines. The equipment included a Speakerphone hands free telephone, with an added box to control picture transmission. Each Picturephone line used three twisted pairs of ordinary telephone cable, two pairs for video and one for audio and signaling. Cable amplifiers were spaced about a mile apart (1.6 Kilometers) with built-in six-band adjustable equalization filters. For distances of more than a few miles, the signal was digitized at 2 MHz and 3 bits per sample DPCM, and transmitted on a T-2 carrier.
The Picturephone was offered to the public in New York City, Washington, DC, Chicago, and Pittsburgh in 1970. The screen was larger than in the original demo units, approximately half a foot (15 cm) square in a roughly cubical cabinet. Picturephone booths were set up in Grand Central Station and elsewhere. With fanfare, Picturephones were installed in offices of Westinghouse in Pittsburgh, and at other progressive companies. Hundreds of technicians attended schools to learn to operate the Cable Equalizer Test Set and other equipment, and to install Picturephones. New wideband crossbar switches were designed and installed into 5XB switch offices, this being the most widespread of the relatively modern kinds. Unrelated difficulties at New York Telephone, however, slowed the effort there, and few customers signed up in either city. A 6 September 2001 report on CNN said the Picturephone service only had a total of 500 subscribers at its peak, and the service faded away by 1974.
AT&T sold the VideoPhone 2500 to the general public in 1992 to 1995 with prices starting at US$1,500 and later US$1,000. 
It was limited by connecting by analog phone lines at about 19 kbit/s; the video portion was 11,200 bit/s, with a maximum frame rate of 10 frames per second, but typically much lower. The VideoPhone 2500 used proprietary protocols.
In 2007, the Smithsonian's National Museum of American History received a wireless picturephone prototype known as intellect, developed in 1993 by inventor Daniel A. Henderson This system and device was designed to receive pictures and video data from a message originator to a message center for transmission and display on a wireless portable device such as a cellular telephone. See also camera phone.
Another protocol used by videophones is H.324, which mixes call setup and video compression. Videophones that work on regular phone lines typically use H.324, but the bandwidth is limited by the modem to around 33 kbit/s, limiting the video quality and framerate. A slightly modified version of H.324 called 3G-324M defined by 3GPP is also used by some cellphones that allow video calls, typically for use only in UMTS networks.
The widest deployment of video telephony occurs in mobile phones, as nearly all mobile phones supporting UMTS networks work as videophones using an internal camera, and are able to make video calls wirelessly to other UMTS users in the same country or internationally. As of Q2 2007, there are over 131 million UMTS users (and hence potential videophone users), on 134 networks in 59 countries.
Videophones can be used by the deaf to communicate with sign language over a distance. In the US the FCC pays companies for providing Video Relay Service to deaf and hard-of-hearing individuals, where they use a videophone to talk through a sign-language translator to people using audio phones. Videophones are also used to do on-site sign-language translation (Video Remote Interpreting). The relatively low cost and widespread availability of mobile phones with video calling capabilities have given deaf people new possibilities to communicate with the same ease as others, with some wireless operators even starting up free sign language gateways.
Videotelephony is used in large corporate conferencing setups, and is supported by systems such as Cisco Unified Communications Manager, and similar systems from companies such as Tandberg, Radvision, and Polycom.
Today the principles, if not the precise mechanisms of a videophone are employed by many users world-wide in the form of webcam conferences using personal computers, with cheaply available webcams and microphones and free instant messenger programs. Thus an activity that was disappointing as a separate service found a niche as a minor feature of products intended for other purposes. A videophone can be created by using an old or inexpensive computer and dedicating it to run a video softphone.
In 2004 Telmex, the biggest telephone service provider in Mexico, introduced Videophone service over regular phone lines (apparently H.324). The service, as of March 2006, had not enjoyed widespread adoption. Telecom Italia supplies LG-Nortel videophones, which also appear to be used by Telmex.
|
|
|
|
|
|
|
|
|
|
|
|