- "Picturephone" and "Visiophone" redirect here. This article discusses the telecommunication technology which originated in the late-1920s; for its modern variants see Videoconferencing and Videotelephony.
A videophone is a telephone with a video display, capable of simultaneous video and audio for communication between people in real-time. Videophone service provided the first form of videotelephony, later to be followed by videoconferencing, webcams, and finally high-definition telepresence.
At the dawn of its commercial deployment from the 1950s through the 1990s, videotelephony also included 'image phones' which would exchange still images between units every few seconds over conventional POTS-type telephone lines, essentially the same as slow scan TV systems. The development of advanced technology video codecs and high bandwidth Internet telecommunication services allowed videophones to provide high quality colour service between users almost anyplace in the world that the Internet is available, often at low or nominal costs.
In the present day videophones have become widely available at reasonable cost, although not widely used in everyday communications for a variety of reasons. However, they are particularly useful to the deaf and speech-impaired who can use them with sign language, and are becoming increasingly popular for educational instruction, telemedicine and to those with mobility issues.
Descriptive names and terminology 
The name 'videophone' never became as standardized as its earlier counterpart 'telephone', resulting in a variety of names and terms being used worldwide, and even within the same region or country. Videophones are also known as 'video phones', 'videotelephones' (or 'video telephones') and often by an early trademarked name Picturephone, which was the world's first commercial videophone produced in volume. The compound name 'videophone' slowly entered into general use after 1950, although 'video telephone' likely entered the lexicon earlier after video was coined in 1935.
Videophone calls (also: videocalls and video chat), differ from videoconferencing in that they expect to serve individuals, not groups. However that distinction has become increasingly blurred with technology improvements such as increased bandwidth and sophisticated software clients that can allow for multiple parties on a call. In general everyday usage the term videoconferencing is now frequently used instead of videocall for point-to-point calls between two units. Both videophone calls and videoconferencing are also now commonly referred to as a video link.
Webcams are popular, relatively low cost devices which can provide live video and audio streams via personal computers, and can be used with many software clients for both video calls and videoconferencing.
A videoconference system is generally higher cost than a videophone and deploys greater capabilities. A videoconference (also known as a videoteleconference) allows two or more locations to communicate via live, simultaneous two-way video and audio transmissions. This is often accomplished by the use of a multipoint control unit (a centralized distribution and call management system) or by a similar non-centralized multipoint capability embedded in each videoconferencing unit. Again, technology improvements have circumvented traditional definitions by allowing multiple party videoconferencing via web-based applications. A separate webpage article is devoted to videoconferencing.
A telepresence system is a high-end videoconferencing system and service usually employed by enterprise-level corporate offices. Telepresence conference rooms use state-of-the art room designs, video cameras, displays, sound-systems and processors, coupled with high-to-very-high capacity bandwidth transmissions.
Typical use of the various technologies described above include calling or conferencing on a one-on-one, one-to-many or many-to-many basis for personal, business, educational, deaf Video Relay Service and tele-medical, diagnostic and rehabilitative use or services. New services utilizing videocalling and videoconferencing, such as teachers and psychologists conducting online sessions, personal videocalls to inmates incarcerated in penitentiaries, and videoconferencing to resolve airline engineering issues at maintenance facilities, are being created or evolving on an on-going basis.
Other names for videophone that have been used in English are: Viewphone (the British Telecom equivalent to AT&T's Picturephone), and visiophone, a common French translation that has also crept into limited English usage, as well as over twenty less common names and expressions. Latin-based translations of videophone in other languages include vidéophone (French), Bildtelefon (German), videotelefono (Italian), both videófono and videoteléfono (Spanish), both beeldtelefoon and videofoon (Dutch), and videofonía (Catalan).
Early history 
Barely two years after the telephone was first patented in the United States in 1876 by Alexander Graham Bell, an early concept of a combined videophone and wide-screen television called a telephonoscope was conceptualized in the popular periodicals of the day. It was also mentioned in various early science fiction works such as Le Vingtième siècle. La vie électrique (the 20th century: the electrical life) and other works written by Albert Robida, and was also sketched in various cartoons by George du Maurier as a fictional invention of Thomas Edison. One such sketch was published on December 9, 1878 in Punch Magazine.
The term 'telectroscope' was also used in 1878 by French writer and publisher Louis Figuier, to popularize an invention wrongly interpreted as real and incorrectly ascribed to Dr. Alexander Graham Bell. Written under the pseudonym "Electrician", an article claimed that "an eminent scientist" had invented a device whereby objects or people anywhere in the world "....could be seen anywhere by anybody". The device, among other functions, would allow merchants to transmit pictures of their wares to their customers, and the contents of museum collections to be made available to scholars in distant cities...."[Note 1] In the era prior to the advent of broadcasting, electrical "seeing" devices were conceived as adjuncts to the telephone, thus creating the concept of a videophone.
Fraudulent reports of 'amazing' advances in video telephones would be publicized as early as 1880 and would reoccur every few years, such as the episode of 'Dr. Sylvestre' of Paris who claimed in 1902 to have invented a powerful (and inexpensive) video telephone, termed a 'spectograph', the intellectual property rights he believed were worth $5,000,000. After reviewing his claim Dr. Bell denounced the supposed invention as a "fairy tale", and publicly commented on the charlatans promoting bogus inventions for financial gain or self-promotion.
However Bell personally thought that videotelephony was achievable even though his contributions to its advancement were incidental. In April 1891, Dr. Alexander Graham Bell did actually record conceptual notes on an 'electrical radiophone', which discussed "....the possibility of seeing by electricity" using devices that employed tellurium or selenium imaging components. Bell wrote, decades prior to the invention of the image dissector:
Should it be found ... [that the image sensor] is illuminated, then an apparatus might be constructed in which each piece of selenium is a mere speck, like the head of a small pin, the smaller the better. The darkened selenium should be placed in a cup-like receiver which can fit over the eye ... Then, when the first selenium speck is presented to an illuminated object, it may be possible that the eye in the darkened receiver, should perceive, not merely light, but an image of the object ...
Bell went on to later predict that: "...the day would come when the man at the telephone would be able to see the distant person to whom he was speaking." The discoveries in physics, chemistry and materials science underlying video technology would not be in place until the mid-1920s, first being utilized in electromechanical television. More practical 'all-electronic' video and television would not emerge until 1939, but would then suffer several more years of delays before gaining popularity due to the onset and effects of World War II.
The compound name 'videophone' slowly entered into general usage after 1950, although 'video telephone' likely entered the lexicon earlier after video was coined in 1935. Prior to that time there appeared to be no standard terms for 'video telephone', with expressions such as 'sight-sound television system', 'visual radio' and nearly 20 others (in English) being used to describe the marriage of telegraph, telephone, television and radio technologies employed in early experiments.
Among the technological precursors to the videophone were telegraphic image transmitters created by several companies, such as the wirephoto used by Western Union, and the teleostereograph developed by AT&T's Bell Labs, which were forerunners of today's fax (facsimile) machines. Such early image transmitters were themselves based on previous work by Ernest Hummel and others in the 19th century. By 1927 AT&T had created its earliest electromechanical television-videophone called the ikonophone (from Greek: 'image-sound'), which operated at 18 frames per second and occupied half a room full of equipment cabinets. An early U.S. test in 1927 had their then-Commerce Secretary Herbert Hoover address an audience in New York City from Washington, D.C; although the audio portion was two-way, the video portion was one-way with only those in New York being able to see Hoover.
By 1930, AT&T's 'two-way television-telephone' system was in experimental use. The Bell Labs' Manhattan facility devoted years of research to it during the 1930s, led by Dr. Herbert Ives along with his team of more than 200 scientists, engineers and technicians, intending to develop it for both telecommunication and broadcast entertainment purposes.
There were also other public demonstrations of "two-way television-telephone" systems during this period by inventors and entrepreneurs who sought to compete with AT&T, although none appeared capable of dealing with the technical issues of signal compression that Bell Labs would eventually resolve. Signal compression, and its later sibling data compression were fundamental to the issue of transmitting the huge bandwidth of low-resolution black and white video through the very limited capacity of ordinary telephone lines (higher resolution colour videophones would require even far greater capabilities).[Note 2] After the Second World War, Bell Labs' efforts would be resumed in the 1950s and 1960s, eventually leading to AT&T's Picturephone.
World's first public videophone service: 1936 
In early 1936 the world's first public video telephone service was developed by Dr. Georg Schubert and opened by the German Reichspost (Post Office) between Berlin and Leipzig, utilizing broadband coaxial cable to cover the distance of approximately 100 miles (160 km). The system employed mechanical television scanning and 8 inches (20 cm) square displays with a resolution of 180 lines operating at 25 frames per second.
Its opening was inaugurated by the Minister of Posts Paul von Eltz-Rübenach in Berlin on March 1, 1936, who viewed and spoke with Leipzig's chief burgomaster. The same coaxial cables were also used to distribute television programming throughout Germany.
In the initial service trial, broadband coaxial cable lines initially linked Berlin to Leipzig. After a period of experimentation the system entered public use and was soon extended 100 miles (160 km) from Berlin to Hamburg, and in July 1938 from Leipzig to Nuremberg and Munich, eventually providing more than 620 miles (1,000 km) of transmission lines. The videophones were integrated within large public telephone booths, with two booths provided per city. Calls between Berlin and Leipzig cost RM3½, approximately one sixth of a British pound sterling, or about one-fifteenth of the average weekly wage. The video telephone equipment in Berlin was designed and built by the German Post Office Laboratory. Devices used in other German cities were developed by Fernseh-Aktiengesellschaft, which was partly owned by the Baird Television Ltd of the U.K., inventors of the world's first working television. While the system's image quality was primitive by modern standards, it was deemed impressive in contemporary reports of the era, with users able to clearly discern the hands on wristwatches.
The special public videotelephone service was offered to the general public, which had to simultaneously visit special post office videophone booths in their respective cities, but which at the same time also had Nazi political and propagandistic overtones similar to the broadcasting of the 1936 Olympic Games in Berlin. The German Post Office announced ambitious plans to extend their public video telephone network to Cologne, Frankfurt and Vienna, Austria, but expansion plans were discontinued in 1939 with the start of the Second World War. The German public videophone system was subsequently closed in 1940.
The Deutsche Bundespost postal service would later develop and deploy its BIGFON (Broadband Integrated Glass-Fiber Optical Network) videotelephony network from 1981 to 1988, serving several large German cities, and also created one of Europe's first public switched broadband services in 1989.
AT&T Picturephone: 1964 
In the United States AT&T's Bell Labs conducted extensive research and development of videophones, eventually leading to public demonstrations of its trademarked Picturephone product and service in the 1960s. Its large Manhattan experimental laboratory devoted years of technical research during the 1930s, led by Dr. Herbert Ives along with his team of more than 200 scientists, engineers and technicians. The Bell Labs early experimental model of 1930 had transmitted uncompressed video through multiple phone lines, a completely impractical (and extremely expensive) method for commercial deployment.
The Picturephone's early promotion included public evaluation displays at Disneyland and the 1964 New York World's Fair, with the first transcontinental videocall between the two venues made on April 20, 1964. The first Picturephone Mod I (Model No. 1) demonstration units used small oval housings on swivel stands, intended to stand on desks. Similar AT&T Picturephone units were also featured at the Telephone Pavilion (also called the "Bell Telephone Pavilion") at Expo 67, an International World's Fair held in Montreal, Canada in 1967. Demonstration units were available at the fairs for the public to test, with fairgoers permitted to make videophone calls to volunteer recipients at other locations.
Right side view, housing removed, one of its printed circuit boards exposed. (Courtesy: Richard Diehl)
The United States would not see its first public videophone booths until 1964, when AT&T installed their earliest commercial videophone units, the Picturephone "Mod I", in booths that were set up in New York's Grand Central Terminal, Washington D.C., and Chicago. Its system was the result of decades of research and development at Bell Labs, its principle supplier, Western Electric, plus other researchers working under contract to the Bell Labs. However the use of reservation time slots and their cost of US$16 to $27 ($118 to $200 in 2012 dollars) for a three-minute call at the public videophone booths greatly limited their appeal resulting in their closure by 1968.
Picturephones were also later installed in the offices of Westinghouse and Alcoa in Pittsburgh, as well as other technology companies in that city. AT&T's commercial service in Pittsburgh started on June 30, 1970 with 38 Picturephones at eight companies, at a lease rate of $160 per month ($947/month in 2012 dollars) for the service, which provided for 30 minutes of videocalling time per month, with extra minutes costing 25 cents each.[Note 3]
Color on AT&T's Picturephone was not employed with their early models. These Picturephone units packaged Plumbicon cameras and small CRT displays within their housings. The cameras were located atop their screens to help users see eye to eye. Later generation display screens were larger than in the original demonstration units, approximately six inches (15 cm) square in a roughly cubical cabinet.
- Further information: Picturephone technology
Lack of Picturephone success 
At the time of its first launch, AT&T foresaw a hundred thousand Picturephones in use across the Bell System by 1975 . However by the end of July 1974, only five Picturephones were being leased in Pittsburgh, and U.S.-wide there were only a few hundred, mostly in Chicago. Unrelated difficulties at New York Telephone also slowed AT&T's efforts, and few customers signed up for the service in either city. At its peak Picturephone service had only about 500 subscribers, with the service fading away thru the 1970s.
AT&T's initial Picturephone 'Mod I' (Model No. 1) and then its upgraded 'Mod II' programs, were a continuation of its many years of prior research during the 1920s, 1930s, late-1940s and the 1950s. Both Picturephone programs, like their experimental AT&T predecessors, were researched principally at its Bell Labs, formally spanned some 15 years and consumed more than US$500 million,[Note 4] eventually meeting with commercial failure. AT&T concluded that its early Picturephone was a "concept looking for a market" and discontinued its 'Mod II' service in the late 1970s.
Later development 
AT&T would later market its VideoPhone 2500 to the general public from 1992 to 1995 with prices starting at US$1,500 (approximately $2,450 in current dollars) and later dropping to $1,000 ($1,590 in current dollars), marketed by its Global VideoPhone Systems unit. The VideoPhone 2500 was designed to provide low-frame rate compressed color video on ordinary Plain Old Telephone Service (POTS) lines, circumventing the significantly higher cost ADSL telephone service lines used by several other videoconferencing manufacturers. Again, AT&T met with very little commercial success, selling only about 30,000 units, mostly outside the United States.
Despite AT&T's various videophone products meeting with commercial failure, they were widely viewed as technical successes which expanded the limits of the telecommunications sciences in several areas. Its videotelephony programs were critically acclaimed for their technical brilliance and even the novel uses they experimented with. The research and development programs conducted by Bell Labs were highly notable for their beyond-the-state-of-the-art results produced in materials science, advanced telecommunications, microelectronics and information technologies.
AT&T's published research additionally helped pave the way for other companies to later enter the field of videoconferencing. The company's videophones also generated significant media coverage in science journals, the general news media and in popular culture. The image of a futuristic AT&T videophone casually being used in the science fiction film 2001: A Space Odyssey, became an icon of both the movie and, arguably, the public's general view of the future.
Other early videophones: 1968–1999 
Beginning in the late 1960s, several countries worldwide sought to compete with AT&T's advanced development of its Picturephone service in the United States. However such projects were research and capital intensive, and fraught with difficulties in being deployed commercially. This time period also saw the research, development and commercial roll-out of what would become powerful video compression and decompression software codecs, which would eventually lead to low cost video telephony.
In France, the defense and electronics manufacturer Matra was one of three French companies that sought to develop videophones in the early 1970s, spurred by the Picturephone in the United States. Initial plans by Matra included the deployment of 25 units to France's Centre national d'études des télécommunications (CNET of France Télécom) for their internal use in 1972. CNET intended to guide its initial use towards the business sector, to be later followed by personal home usage. Its estimated unit cost in 1971 was the equivalent of £325, with a monthly usage subscription charge of £3.35.
Studies of applications of videotelephony were conducted by CNET in France in 1972, with its first commercial applications for videophones appearing in 1984. The delay was due to the problem of insufficient bandwidth, with 2 Mb per second being required for transmitting both video and audio signals. The problem was solved worldwide by the creation of software for data encoding and compression via video coding and decoding algorithms, also known as codecs.
In Sweden electronics maker Ericsson began developing a videophone in the mid-1960s, intending to market it to government, institutions, businesses and industry, but not to consumers due to AT&T's lack of success in that market segment. Tests were conducted in Stockholm, including trial communications in banking in Stockholm. Ultimately Ericsson chose not to proceed with further production.
In Japan the Lumaphone was developed and marketed by Mitsubishi in 1985. The project was originally started by the Ataritel division of the Atari Video Game Company in 1983 under the direction of Atari's Steve Bristow. Atari then sold its division to Mitsubishi Electric in 1984. The Lumaphone was marketed by Mitsubishi Electric of America in 1986 as the Luma LU-1000, designed with a small black and white video display, approximately 4 centimetres (1.6 in) in size, and a video camera adjacent to the display which could be blocked with a sliding door for privacy. Similar to Bell Labs' very early image transfer phone of 1956, it could transmit still images every 3–5 seconds over analog POTS lines, and could also be hooked up to a printer or connected to a regular TV or monitor for improved teleconferencing. A larger video image was available by attaching its optional VisiTel LU-500 display.
Videophone improvements: post-2000 
Significant improvements in video call quality of service for the deaf occurred in the United States in 2003 when Sorenson Media Inc. (formerly Sorenson Vision Inc.), a video compression software coding company, developed its VP-100 model stand-alone videophone specifically for the deaf community. It was designed to output its video to the user's television in order to lower the cost of acquisition, and to offer remote control and a powerful video compression codec for unequaled video quality and ease of use with video relay services. Favourable reviews quickly led to its popular usage at educational facilities for the deaf, and from there to the greater deaf community.
Coupled with similar high-quality videophones introduced by other electronics manufacturers, the availability of high speed Internet, and sponsored video relay services authorized by the U.S. Federal Communications Commission in 2002, VRS services for the deaf underwent rapid growth in that country.
Current videophone usage 
The widest deployment of video telephony now occurs in mobile phones, as nearly all mobile phones supporting UMTS networks can work as videophones using their internal cameras, and are able to make video calls wirelessly to other UMTS users in the same country or internationally. As of the second quarter of 2007, there are over 131 million UMTS users (and hence potential videophone users), on 134 networks in 59 countries.
Videophones are increasingly used in the provision of telemedicine to the elderly and to those in remote locations, where the ease and convenience of quickly obtaining diagnostic and consultative medical services are readily apparent. In one single instance quoted in 2006: "A nurse-led clinic at Letham has received positive feedback on a trial of a video-link which allowed 60 pensioners to be assessed by medics without travelling to a doctor's office or medical clinic." A further improvement in telemedical services has been the development of new technology incorporated into special videophones to permit remote diagnostic services, such as blood sugar level, blood pressure and vital signs monitoring. Such units are capable of relaying both regular audiovideo plus medical data over either standard (POTS) telephone or newer broadband lines.
Videotelephony has also been deployed in corporate teleconferencing, also available through the use of public access videoconferencing rooms. A higher level of videoconferencing that employs advanced telecommunication technologies and high-resolution displays is called telepresence.
Today the principles, if not the precise mechanisms of a videophone are employed by many users worldwide in the form of webcam videocalls using personal computers, with inexpensive webcams, microphones and free videocalling Web client programs. Thus an activity that was disappointing as a separate service has found a niche as a minor feature in software products intended for other purposes.
According to Juniper Research, smartphone videophone users will reach 29 million by 2015 globally.
General lack of public acceptance 
Early AT&T Picturephones had few users, in part because the service was relatively expensive with an initial installation cost in 1970 of $169 (approximately $1,000 in current dollars) and a monthly cost of $169, plus 25 cents per minute after the first 30 minutes. AT&T dropped its rates the next year to $75 per month (approx. $440 a month today) without an installation charge, plus 15 cents a minute after the first 30 minutes. With a then-contemporary rate of about $5 a month ($30 today) for regular voice service there were very few residential subscribers.
However as modern technology reduced videotelephony costs to nominal, at least in the case of webcams, videophone calling continued to be only marginally utilized. This contrasts to many early, overly optimistic views that videotelephony would become ubiquitous.
There are several other reasons why videotelephony remains a peripheral telecommunications technology. One of the most important may be psychological: just as many people choose to listen to radio instead of watching television, individuals can prefer regular telephone conversations over videophone calls. This reason for poor acceptance may reflect that people can actually desire less fidelity in their communications. Additionally, others did not want to be seen at home—where a videophone can be viewed as too intrusive into one's private life. The reasoning and psychology can be summed as, although its true that "one picture can say a thousand words", its also true that, in poor situations, "one picture can say a thousand negative words".
Another reason may be that videophone calling can be a poor analog for direct face-to-face conversation. Videophone users commonly look at the video screen and not at the video camera, preventing users from having direct eye-to-eye contact, as the video cameras are usually positioned away from the screen. The issue of poor eye contact has been addressed on the more sophisticated videophone and videoconferencing systems (as far back as the 1960s) by means of cameras hidden behind translucent display screens, directly inline with the projected image of the person being spoken to.
In addition to the loss of eye contact, a more fundamental problem of lip-sync affects many videophone solutions. Audio signals can become out of sync with the visual image resulting in the subject's speech being at odds or out of phase with lip movements. A research paper published by the IEEE reveals that most viewers are more sensitive to audio/video misalignment when audio plays before the corresponding video, because hearing the spoken word before seeing the lips move is more "unnatural" to a viewer (Blakowski and Steinmetz 1996). Sensitivity to skew is also determined by the frame rate and resolution: Viewers are more sensitive to skew when watching higher video resolution or at a higher frame rate.
However it's also been observed that videotelephony is of great benefit to certain groups and demographics, such as members of families living far apart and who may have a strong desire, but little opportunity for face-to-face contact. Other groups that have embraced videotelephony include those in the deaf community where high quality video greatly facilitates sign language communications both within and outside of their personal and social settings. The elderly and those who are physically immobile also benefit from video telecommunications.
Sign language communications via videophones 
One of the first demonstrations of the ability for telecommunications to help sign language users communicate with each other occurred when AT&T's videophone (trademarked as the "Picturephone") was introduced to the public at the 1964 New York World's Fair –two deaf users were able to communicate freely with each other between the fair and another city. Various universities and other organizations, including British Telecom's Martlesham facility, have also conducted extensive research on signing via videotelephony. The use of sign language via videotelephony was hampered for many years due to the difficulty of its use over slow analogue copper phone lines, coupled with the high cost of better quality ISDN (data) phone lines. Those factors largely disappeared with the introduction of more efficient video codecs and the advent of lower cost high-speed ISDN data and IP (Internet) services in the 1990s.
21st century improvements for signing 
Significant improvements in video call quality of service for the deaf occurred in the United States in 2003 when Sorenson Media Inc. (formerly Sorenson Vision Inc.), a video compression software coding company, developed its VP-100 model stand-alone videophone specifically for the deaf community. It was designed to output its video to the user's television in order to lower the cost of acquisition, and to offer remote control and a powerful proprietary video compression codec for unequaled video quality and ease of use with video relay services. Favourable reviews quickly led to its popular usage at educational facilities for the deaf, and from there to the greater deaf community.
Coupled with similar high-quality videophones introduced by other electronics manufacturers, the availability of high speed Internet, and sponsored video relay services authorized by the U.S. Federal Communications Commission in 2002, VRS services for the deaf underwent rapid growth in that country.
Present day usage by signers 
Using such video equipment in the present day, the deaf, hard-of-hearing and speech-impaired can communicate between themselves and with hearing individuals using sign language. The United States and several other countries compensate companies to provide "Video Relay Services" (VRS). Telecommunication equipment can be used to talk to others via a sign language interpreter, who uses a conventional telephone at the same time to communicate with the deaf person's party. Video equipment is also used to do on-site sign language translation via Video Remote Interpreting (VRI). The relative low cost and widespread availability of 3G mobile phone technology with video calling capabilities have given deaf and speech-impaired users a greater ability to communicate with the same ease as others. Some wireless operators have even started free sign language gateways.
Sign language interpretation services via VRS or by VRI are useful in the present-day where one of the parties is deaf, hard-of-hearing or speech-impaired (mute). In such cases the interpretation flow is normally within the same principal language, such as French Sign Language (LSF) to spoken French, Spanish Sign Language (LSE) to spoken Spanish, British Sign Language (BSL) to spoken English, and American Sign Language (ASL) also to spoken English (since BSL and ASL are completely distinct to each other), and so on.
Multilingual sign language interpreters, who can also translate as well across principal languages (such as to and from SSL, to and from spoken English), are also available, albeit less frequently. Such activities involve considerable effort on the part of the translator, since sign languages are distinct natural languages with their own construction, semantics and syntax, different from the aural version of the same principal language.
With video interpreting, sign language interpreters work remotely with live video and audio feeds, so that the interpreter can see the deaf or mute party, and converse with the hearing party, and vice versa. Much like telephone interpreting, video interpreting can be used for situations in which no on-site interpreters are available. However, video interpreting cannot be used for situations in which all parties are speaking via telephone alone. VRS and VRI interpretation requires all parties to have the necessary equipment. Some advanced equipment enables interpreters to control the video camera remotely, in order to zoom in and out or to point the camera toward the party that is signing.
Bandwidth requirements 
Videophones have historically employed a variety of transmission and reception bandwidths, which can be understood as data transmission speeds. The lower the transmission/reception bandwidth, the lower the data transfer rate, resulting in a more limited and poorer image quality. Data transfer rates and live video image quality are related, but are also subject to other factors such as data compression techniques. Some early videophones employed very low data transmission rates with a resulting sketchy video quality.
Broadband bandwidth is often called "high-speed", because it usually has a high rate of data transmission. In general, any connection of 256 kbit/s (0.256 Mbit/s) or greater is more concisely considered broadband Internet. The International Telecommunication Union Standardization Sector (ITU-T) recommendation I.113 has defined broadband as a transmission capacity at 1.5 to 2 Mbit/s. The United States Federal Communications Commission definition of broadband is 768 kbit/s (0.8 Mbit/s).
Currently, adequate video for some purposes becomes possible at data rates lower than the ITU-T broadband definition, with rates of 768 kbit/s and 384 kbit/s used for some video conferencing applications, and rates as low as 100 kbit per second used for videophones using H.264/MPEG-4 AVC compression protocols. The newer MPEG-4 video and audio compression format can deliver high-quality video at 2 Mbit/s, which is at the low end of cable modem and ADSL broadband performance.
Picturephone technology 
The Picturephone's video bandwidth was 1 MHz with a 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 kilometres) 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 original Picturephone system used contemporary crossbar and multi-frequency operation. Lines and trunks were six wire, one pair each way for video and one pair two way for audio. MF address signaling on the audio pair was supplemented by a Video Supervisory Signal (VSS) looping around on the video quad to ensure continuity. More complex protocols were later adopted for conferencing.
To deploy Picturephone service new wideband crossbar switches were designed and installed into the Bell System's 5XB switch offices, this being the most widespread of the relatively modern kind. Hundreds of technicians attended schools to learn to operate the Cable Equalizer Test Set and other equipment, and to install Picturephones.
AT&T later marketed its colour VideoPhone 2500 to the general public from 1992 to 1995. It was limited by analog phone line connection speeds of about 19 Kilobits per second, the video portion being 11,200 bit/s, and with a maximum frame rate of 10 frames per second, but typically much slower, as low as a third of a video frame per second. The VideoPhone 2500 used proprietary technology protocols, including AT&T's Global VideoPhone Standard (GVS).
Call setup 
Videoconferencing in the late 20th century was limited to the H.323 protocol (notably Cisco's SCCP implementation was an exception), but newer videophones often use SIP, which is often easier to set up in home networking environments. It is a text-based protocol, incorporating many elements of the Hypertext Transfer Protocol (HTTP) and the Simple Mail Transfer Protocol (SMTP). H.323 is still used, but more commonly for business videoconferencing, while SIP is more commonly used in personal consumer videophones. A number of call-setup methods based on instant messaging protocols such as Skype also now provide video.
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 frame rate. 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.
There is also H.320 standard, which specified technical requirements for narrow-band visual telephone systems and terminal equipment, typically for videoconferencing and videophone services. It applied mostly to dedicated circuit-based switched network (point-to-point) connections of moderate or high bandwidth, such as through the medium-bandwidth ISDN digital phone protocol or a fractionated high bandwidth T1 lines. Modern products based on H.320 standard usually support also H.323 standard.
The IAX2 protocol also supports videophone calls natively, using the protocol's own capabilities to transport alternate media streams.
Popular culture 
In science fiction literature, names commonly associated with videophones included vidphone, vidfone, visiphone, and viewphone. In many science fiction movies and TV programs that were set in the future, videophones were used as a primary method of communication. One of the first movies where a videophone was used was Fritz Lang’s Metropolis (1927).
Other notable examples of videophones in popular culture include an iconic scene from 2001: A Space Odyssey that was set on Space Station V. The movie was released shortly before AT&T began its efforts to commercialize its Picturephone Mod II service in several cities and depicted a videocall to Earth using an advanced AT&T videophone—ironically costing only $1.75, a fraction of the company's real rate's on Earth when the movie was released. In that scene Dr. Heywood Floyd talks with and views his daughter at home from a space station in orbit above the Earth, discussing what type of present he should bring home for her.
A portable videophone was also featured prominently in the 2009 science fiction movie Moon, when the story's protagonist, Sam Bell, the lone occupant of a mining station on the far side of the Earth's moon, finally succeeds in making a videocall to his home after an extended work contract there, and is then traumatized while viewing his daughter.
Other popular science fiction stories with videophones include Space: 1999, Star Trek, Total Recall, Blade Runner, and Firefly. Of particular note, the videophone was a staple, everyday technology in the futuristic Hanna Barbera cartoon The Jetsons.
Other earlier examples of videophones in popular culture included a videophone that was featured in the Warner Bros. cartoon, Plane Daffy, in which the female spy Hatta Mari used a videophone to communicate with Adolf Hitler (1944), as well as a device with the same functionality has been used by the comic strip character Dick Tracy. Called the '2-Way Wrist TV', the fictional detective often used the phone to communicate with police headquarters (1964–1977).
By the early 2010s videotelephony and videophones had become commonplace and unremarkable in various forms of media, in part due to their real and ubiquitous presence in common electronic devices and laptop computers. Additionally, TV programming increasingly utilized videophones to interview persons of interest and to present live coverage by news correspondents, via the Internet or transmitted by satellite links. In the mass market media, the popular U.S. TV talk show hostess Oprah Winfrey incorporated videotelephony into her TV program on a regular basis from May 21, 2009, with an initial episode called Where the Skype Are You?, as part of a marketing agreement with the Internet telecommunication company Skype.
Additionally, videophones have been featured in:
- E.M. Forster's 1909 short story The Machine Stops is set in a dystopian future in which, for the most part, human interaction has been reduced to communication via a kind of videoconferencing device called the "speaking apparatus";
- several episodes of Thunderbirds (1965–66). These were shown to also have an audio-only setting, which was indicated by the words SOUND ONLY SELECTED being displayed on the screen;
- the British cartoon DangerMouse, where the title character regularly communicated with headquarters via videophones from both his home and his car (1981–1992);
- the movie Gremlins 2: The New Batch, where AT&T's VideoPhone 2500 prototypes are visible (1990);
- Lisa's Wedding, an episode of The Simpsons which depicted a Picturephone (1995).
- the popular television series Pee-Wee's Playhouse, Pee-wee Herman often made and received calls on a videophone-like 'magic screen' (1986–1990);
- the movie Back to the Future Part II, where the future Marty McFly is contacted by Needles, his coworker, and then by his boss Mr. Fujitsu, via videophone (1989);
- the novel Infinite Jest, where the videophone (specifically the fall of the videophone) is spoken of extensively (1996);
- the animated television program Futurama, where the videophone is often used within the delivery service spaceship (1999 – present);
- the Pokémon anime series, where Videophones were occasionally used (2006–2011);
- a Beyoncé Knowles pop single and music video called Video Phone from her album "I am... Sasha Fierce" (2008).
See also 
|Look up videophone in Wiktionary, the free dictionary.|
|Wikimedia Commons has media related to: Videophones|
- Although the pseudonymous letter was accompanied by a technical description of how the telectroscope would work and was published in a reputable New York newspaper, researchers later noted that it was published close to April Fools Day and believed the article was submitted as an elaborate hoax.
- One such demonstration that likely omitted any signal compression was performed in Mobile, Alabama on April 27, 1938. An Alabama news article reported that a "...technician of the American Television Institute, [promoted a videophone from a display booth for] the Roche Home Equipment Company... and through the medium of a scientific marvel... flashed a living picture over an ordinary telephone wire. Forming a practical insight into things that are to come, the television contrivance afforded a small, but clear, picture of speakers at each end of the wire." 
- Several uses of the Picturephone were novel and ahead of their time. At Alcoa in Pittsburgh, their Picturephone system was integrated into the company's corporate Information Technology system under its APRIS, or Alcoa Picturephone Remote Information System. APRIS let users retrieve information from Alcoa's databases, controlled by the buttons on their touch-tone telephones, with the data being presented on their Picturephone's video display, long before computer monitors came into popular use. AT&T's Bell Labs would also soon experiment with multiple users on the same videocall, creating one of the earliest forms of videoconferencing.
- The $500M figure is attributed only to the AT&T and Bell Labs' 15 year program covering its Picturephone Mod I and Mod II versions. Earlier videotelephony programs during the later half of the 1920s, the 1930s, late-1940s and the 1950s, plus the AT&T VideoPhone 2500 model program of the late-1980s led to a cumulative cost which approached, by some estimates, one billion dollars in total for all videotelephony development.
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Further reading 
- Bajaj, Vikas. Transparent Government, Via Webcams in India, The New York Times, July 18, 2011, pg.B3. Published online: July 17, 2011.
- Davis, Andrew W.; Weinstein, Ira M. The Business Case for Videoconferencing, Wainhouse Research, March 2005.
- Hoffman, Jan. When Your Therapist Is Only a Click Away, The New York Times, September 25, 2011, pg. ST1. Also published September 23, 2011 online at www.nytimes.com.
- ProAV Magazine. Being There ProAV Magazine, 7 November 2008.
- Saint Louis, Catherine. With Enough Bandwidth, Many Join The Band, The New York Times, January 10, 2012 (online), January 11, 2012 (in print, New York Edition, pg. A1). Retrieved online January 11, 2012. Synopsis: a look at the pros and cons of videotelephony used for private, individual, music lessons.
- Steinberg, Neil. Dude, Where's My Video Phone?, Forbes.com website, October 15, 2007
- Debut of the First Picturephone, 1970 video courtesy of AT&T Archives and History Center, Warren, N.J.
- TVTropes.org: Video Phone, includes extensive lists of videophones used in popular culture
- Wirlpool Forums: Movies that feature videophones