Videotelephony

"Videophone" redirects here. For other uses, seeVideophone (disambiguation).

Videotelephony(also known asvideoconferencingorvideo calling) is the use ofaudioandvideofor simultaneoustwo-way communication.Today, videotelephony is widespread. There are many terms to refer to videotelephony.Videophonesare standalone devices for video calling (compareTelephone). In the present day, devices likesmartphonesand computers are capable of video calling, reducing the demand for separate videophones.Videoconferencingimplies group communication.Videoconferencing is used intelepresence,whose goal is to create the illusion that remote participants are in the same room.

Atelepresencesystem in 2007

The concept of videotelephony was conceived in the late 19th century, and versions were available to the public starting in the 1930s. Early demonstrations were installed at booths in post offices and shown at various world expositions. In 1970,AT&Tlaunched the first commercial personal videotelephone system. In addition to videophones, there existedimage phoneswhich exchanged still images between units every few seconds overconventional telephone lines.The development of advancedvideo codecs,more powerfulCPUs,and high-bandwidthInternet servicein the late 1990s allowed digital videophones to provide high-quality low-cost color service between users almost any place in the world.

Applications of videotelephony includesign languagetransmission fordeafandspeech-impairedpeople,distance education,telemedicine,and overcomingmobility issues.News mediaorganizations have used videotelephony for broadcasting.

History

Main article:History of videotelephony

Videotelephony predicted to be in use by 2000, as envisioned in 1910 (artist's conception)

Videotelephone booth, 1922

Origin

The concept of videotelephony was first conceived in the late 1870s, both in the United States and in Europe, although the basic sciences to permit its very earliest trials would take nearly a half century to be discovered.The prerequisite knowledge arose from intensive research and experimentation in several telecommunication fields, notablyelectrical telegraphy,telephony,radio,andtelevision.

Early systems

Simple analog videophone communication could be established as early as the invention of thetelevision.Such an antecedent usually consisted of twoclosed-circuit televisionsystems connected viacoax cableorradio.An example of that was the German Reich Postzentralamt (post office) videotelephone network serving Berlin and several German cities via coaxial cables between 1936 and 1940.

The development of videotelephony as a subscription service started in the latter half of the 1920s in the United Kingdom and the United States, spurred notably byJohn Logie BairdandAT&T's Bell Labs.This occurred in part, at least with AT&T, to serve as an adjunct supplementing the use of the telephone. A number of organizations believed that videotelephony would be superior to plain voice communications. Attempts at using normaltelephonynetworks to transmit slow-scan video, such as the first systems developed byAT&T Corporation,first researched in the 1950s, failed mostly due to the poor picture quality and the lack of efficientvideo compressiontechniques.

During the first crewedspace flights,NASAused two radio-frequency (UHForVHF) video links, one in each direction.TVchannels routinely use this type of videotelephony when reporting from distant locations. The news media were to become regular users of mobile links tosatellitesusing specially equipped trucks, and much later via special satellite videophones in a briefcase. This technique was very expensive, though, and was not adopted for applications such astelemedicine,distance education,and business meetings.

Decades of research and development culminated in the 1970 commercial launch of AT&T'sPicturephoneservice, available in select cities. However, the system was a commercial failure, chiefly due to consumer apathy, high subscription costs, and lack ofnetwork effect—with only a few hundred Picturephones in the world, users had extremely few contacts they could actually call, andinteroperabilitywith other videophone systems would not exist for decades.

Multiple user videoconferencing first being demonstrated withStanford Research Institute'sNLS computer technology(1968)

An AT&T Picturephone Model 2 from 1969

Digital

In the 1980s,digital telephonytransmission networks became possible, such as withISDNnetworks. During this time, there was also research into other forms of digital video and audio communication. Many of these technologies, such as theMedia space,are not as widely used today as videoconferencing but were still an important area of research.The first dedicated systems started to appear as ISDN networks were expanding throughout the world. One of the first commercial videoconferencing systems sold to companies came fromPictureTel Corp.,which had aninitial public offeringin November, 1984.

In 1984, Concept Communication in the United States created acircuit boardfor standard personal computers that doubled the videoframe rateof typical digital videotelephone systems from 15 to 30 frames per second, and reduced the cost from $100,000 to $12,000.The company also secured a patent for acodecfor full-motion videoconferencing, first demonstrated atAT&T Bell Labsin 1986.

Global Schoolhouse students communicating viaCU-SeeMe,shown here with a videoframe ratebetween 0.9 and 3 frames per second (1993)

Very expensive videoconferencing systems continued to rapidly evolve throughout the 1980s and 1990s. Proprietary equipment, software, and network requirements gave way to standards-based technologies that were available for anyone to purchase at a reasonable cost.

While videoconferencing technology was initially used primarily within internal corporate communication networks, one of the first community service uses of the technology started in 1992 through a unique partnership with PictureTel and IBM, which at the time were promoting a jointly developed desktop based videoconferencing product known as the PCS/1. Over the next 15 years,Project DIANE(Diversified Information and Assistance Network) grew to use a variety of videoconferencing platforms to create a multi-state cooperative public service and distance education network consisting of several hundred schools, libraries, science museums, zoos and parks, and many other community-oriented organizations.

Transition to internet and mobile devices

Advances invideo compressionalloweddigital videostreams to be transmitted over the Internet, which was previously difficult due to the impractically high bandwidth requirements ofuncompressed video.The DCT algorithm was the basis for the first practicalvideo coding standardthat was useful for online videoconferencing,H.261,standardised by theITU-Tin 1988, and subsequentH.26xvideo coding standards.

In 1992CU-SeeMewas developed at Cornell by Tim Dorcey et al. In 1995 thefirst public videoconference between North America and Africatook place, linking a technofair inSan Franciscowith a techno-rave and cyberdeli inCape Town.At the1998 Winter Olympicsopening ceremony inNagano,Japan,Seiji Ozawaconducted theOde to JoyfromBeethoven's Ninth Symphonysimultaneously across five continents in near-real-time.

TheKyoceraVP-210 Visual Phone was the first commercial mobile videophone (1999).

Kyoceraconducted a two-year development campaign from 1997 to 1999 that resulted in the release of the VP-210 Visual Phone, the first mobile colour videophone that also doubled as acamera phonefor still photos.The camera phone was the same size as similar contemporarymobile phones,but sported a large camera lens and a 5 cm (2 inch) colourTFT displaycapable of displaying 65,000 colors, and was able to process two video frames per second.

Videotelephony was popularized in the 2000s via free Internet services such asSkypeandiChat,web plugins supportingH.26xvideo standards, and online telecommunication programs that promoted low cost, albeit lower quality, videoconferencing to virtually every location with an Internet connection.

Videotelephony became even more widespread through the deployment of video-enabledmobile phonessuch as 2010siPhone 4,plus videoconferencing andcomputer webcamswhich useInternet telephony.In the upper echelons of government, business, and commerce,telepresence technology,an advanced form of videoconferencing, has helped reduce the need to travel.

Additional history

In May 2005, the firsthigh definitionvideoconferencing systems, produced byLifesize,were displayed at theInteroptrade show inLas Vegas,Nevada,able to provide video at 30 frames per second with a 1280 by 720display resolution.Polycomintroduced its first high definition videoconferencing system to the market in 2006. As of the 2010s, high-definition resolution for videoconferencing became a popular feature, with most major suppliers in the videoconferencing market offering it.

Technological developments by videoconferencing developers in the 2010s have extended the capabilities of videoconferencing systems beyond the boardroom for use withhand-held mobile devicesthat combine the use of video, audio and on-screen drawing capabilities broadcasting in real time over secure networks, independent of location.Mobile collaborationsystems now allow people in previously unreachable locations, such as workers on an offshore oil rig, the ability to view and discuss issues with colleagues thousands of miles away. Traditional videoconferencing system manufacturers have begun providing mobile applications as well, such as those that allow for live and still image streaming.

The highest ever video call (other than those from aircraft and spacecraft) took place on May 19, 2013, when British adventurer Daniel Hughes used asmartphonewith aBGAN satellite modemto make a videocall to theBBCfrom the summit ofMount Everest,at 8,848 metres (29,029 ft) above sea level.

TheCOVID-19 pandemicresulted in a significant increase in the use of videoconferencing. Berstein Research found thatZoomadded more subscribers during the first two months of 2020 alone than in the entire year 2019.GoToMeetinghad a 20 percent increase in usage, according toLogMeIn.UK basedStarLeafreported a 600 percent increase in national call volumes.Videoconferencing became so widespread during the pandemic that the termZoom fatiguecame to prominence, referring to the ta xing nature of spending long periods of time on videocalls.This fatigue refers to the psychological and physiological effects participants involved in videoconferencing.One experimental study from 2021 revealed a link between camera use in videoconferencing and a prediction of fatigue occurrence an individual.Furthermore, a 2022 article in the journal "Computers in Human Behaviour"highlighted a study linking negative attitudes with the use of" self-view "when videoconferencing.

On 21 September 2021,Facebooklaunched two new versions of its Portal video-calling devices, the Portal Go and Portal Plus. The new video calling devices include the first portable variety of the hardware and number of updates.

Major categories

A modernAvayaNortel1535 IP model broadband videophone (2008), usingVoIP

USB webcam for PC

Videotelephony can be categorized by its functionality and intended purpose, and also by its method of transmission.

Videophoneswere the earliest form of videotelephony, dating back to initial tests in 1927 by AT&T. During the late 1930s, the post offices of several European governments established public videophone services for person-to-person communications using dual cable circuit telephone transmission technology. In the present day, standalone videophones andUMTSvideo-enabledmobile phonesare usually used on a person-to-person basis.

Videoconferencingsaw its earliest use with AT&T's Picturephone service in the early 1970s. Transmissions were analog over short distances, but converted to digital forms for longer calls, again using telephone transmission technology. Popular corporate video-conferencing systems in the present day have migrated almost exclusively to digitalISDNandIPtransmission modes due to the need to convey the very large amounts of data generated by their cameras and microphones. These systems are often intended for use in conference mode, that is by many people in several different locations, all of whom can be viewed by every participant at each location.

Telepresencesystems are a newer, more advanced subset of videoconferencing systems, meant to allow higher degrees of video and audio fidelity. Such high-end systems are typically deployed in corporate settings.

Mobile collaborationsystems are another recent development, combining the use of video, audio, and on-screen drawing capabilities using newest generationhand-held electronic devicesbroadcasting over secure networks, enabling multi-party conferencing in real time, independent of location.Proximity chatis another alternative mode, focused on the flexibility of small group conversations.

A more recent technology encompassing these functions is TV cams. TV cams enable people to make video calls using video calling services, like Skype on their TV, without using a PC connection. TV cams are specially designed video cameras that feed images in real time to another TV camera or other compatible computing devices like smartphones, tablets and computers.

Webcamsare popular, relatively low-cost devices that can provide live video and audio streams viapersonal computers,and can be used with manysoftware clientsfor both video calls and videoconferencing.

Each of the systems has its own advantages and disadvantages, includingvideo quality,capital cost,degrees of sophistication,transmissioncapacity requirements, andcost of use.

By cost and quality of service

From the least to the most expensive systems:

• Web cameravideophone and videoconferencing systems, either stand-alone or built-in, that serve as complements to personal computers, connected to other participants bycomputerandVoIPnetworks—lowest direct cost, assuming the users already possess computers at their respective locations. Quality of service can range from low to very high, includinghigh definitionvideo available on the latest model webcams. A related and similar device is a TV camera which is usually small, sits on top of a TV, and can connect to it via itsHDMIport, similar to how a webcam attaches to a computer via a USB port.
• Videophones—low to midrange cost. The earliest standalone models operated over eitherplain old telephone service(POTS) lines on thePSTNtelephone networks or more expensiveISDNlines, while newer models have largely migrated toInternet Protocolline service for higher image resolutions and sound quality. Quality of service for standalone videophones can vary from low to high;
• Huddle room or all-in-one systems —low to midrange cost, newer endpoint category based on standard videoconferencing systems, but defined by the camera, microphone(s), speakers, and codec contained in a single piece of hardware. Typically used in small to medium spaces wherebeamformingmicrophone arrayslocated in the system are sufficient, in lieu of table or ceiling microphones in closer proximity to the in-room participants. Quality of service is comparable to standard videoconferencing systems, varying from moderate to high. Some manufacturers' huddle room systems do not include the codec within the soundbar-shaped unit, rather only camera, microphone, and speakers. These systems are usually still classified as huddle room systems, but, like webcams, rely on a USB connection to an external device, usually a PC, to process the video codec responsibilities. Despite its name, video conferencing systems for Huddle Rooms prevent participants from huddling close together to be seen in the camera. All-in-one systems for these types of rooms range from wide angles such as 110° Horizontal field of view (FOV) to as much as 360° FOV that allow a full view of the room.
• Videoconferencing systems—midrange cost, usually usingmultipoint control unitsor other bridging services to allow multiple parties on videoconference calls. Quality of service can vary from moderate to high.
• Telepresence systems—highest capabilities and highest cost. Fullhigh-endsystems can involve specially built teleconference rooms to allow expansive views with very high levels of audio and video fidelity, to permit an 'immersive' videoconference. When the proper type and capacity transmission lines are provided between facilities, the quality of service reaches state-of-the-art levels.

Security concerns

Computer securityexperts have shown that poorly configured or inadequately supervised videoconferencing systems can permit an easyvirtualentry bycomputer hackersand criminals into company premises and corporate boardrooms.

Adoption

For over a century,futuristshave envisioned a future where telephone conversations will take place as actual face-to-face encounters with video as well as audio. Sometimes it is simply not possible or practical to have face-to-face meetings with two or more people. Sometimes a telephone conversation or conference call is adequate. Other times,e-mailexchanges are adequate. However, videoconferencing adds another option and can be considered when:

• A live conversation is needed
• Non-verbal (visual) information is an important component of the conversation
• The parties of the conversation cannot physically come to the same location
• The expense or time of travel is a consideration

Bill Gatessaid in 2001 that he used videoconferencing "three or four times a year", because digital scheduling was difficult and "if the overhead is super high, then you might as well just have a face-to-face meeting".Some observers argue that three outstanding issues have prevented videoconferencing from becoming a widely adopted form of communication, despite the ubiquity of videoconferencing-capable systems.

• Eye contact:Eye contactplays a large role in conversationalturn-taking,perceived attention and intent, and other aspects of group communication.While traditional telephone conversations give no eye contact cues, many videoconferencing systems are arguably worse in that they provide an incorrect impression that the remote interlocutor is avoiding eye contact. Some telepresence systems have cameras located in the screens that reduce the amount ofparallaxobserved by the users. This issue is also being addressed through research that generates a synthetic image with eye contact using stereo reconstruction.
  Telcordia Technologies,formerly Bell Communications Research, owns a patent for eye-to-eye videoconferencing using rear projection screens with the video camera behind it, evolved from a 1960s U.S. military system that provided videoconferencing services between theWhite Houseand various other government and military facilities. This technique eliminates the need for special cameras or image processing.
• Appearance consciousness:A second psychological problem with videoconferencing is being on camera, with the video stream possibly even being recorded. The burden of presenting an acceptable on-screen appearance is not present in audio-only communication. Early studies by Alphonse Chapanis found that the addition of video actually impaired communication, possibly because of the consciousness of being on camera.
• Signal latency:The information transport of digital signals in many steps need time. In a telecommunicated conversation, an increasedlatency(time lag) larger than about 150–300 ms becomes noticeable and is soon observed as unnatural and distracting. Therefore, next to a stable large bandwidth, a smalltotal round-trip timeis another major technical requirement for the communication channel for interactive videoconferencing.
• Bandwidth and quality of service:In some countries, it is difficult or expensive to get a high-quality connection that is fast enough for good-quality videoconferencing. Technologies such asADSLare usually provided as two separate lines (for uplink/downlink) because each has limited upload speeds and cannot upload and download simultaneously at full speed. As Internet speeds increase, higher quality and high-definition videoconferencing will become more readily available.
• Complexity of systems:Most users are not technically experienced and want a simple interface. In hardware systems, an unplugged cord or an unresponsive remote control is seen as a failure, contributing to a perceived unreliability. Successful systems are backed by support teams who can provide fast assistance when required.
• Perceived lack of interoperability:Not all systems can readily interconnect; for example, ISDN and IP systems require a gateway. Popular software solutions cannot easily connect to hardware systems. Some systems use different standards, features, and qualities which can require additional configuration when connecting to dissimilar systems. Free software systems circumvent this limitation by making it relatively easy for a single user to communicate over multiple incompatible platforms.
• Expense of commercial systems:Well-designedtelepresencesystems require specially designed rooms which can cost hundreds of thousands of dollars to fit out their rooms with codecs, integration equipment (such asMultipoint Control Units), high fidelity sound systems, and furniture. Monthly charges may also be required for bridging services and high-capacity broadband service.

These are some of the reasons many organizations only use the systems internally, where there is less risk of loss of customers. An alternative for those lacking dedicated facilities is therental of videoconferencing-equipped meeting roomsin cities around the world. Clients can book rooms and turn up for the meeting, with all technical aspects being prearranged and support being readily available if needed. The issue of eye contact may be solved with advancing technology, including smartphones which have the screen and camera in essentially the same place. In developed countries, the near-ubiquity ofsmartphones,tablet computers,and computers with built-in audio and webcams removes the need for expensive dedicated hardware.

Technology

Components and types

Dual display:A mid-2000sPolycom VSX 7000system and camera used for videoconferencing, with two displays for simultaneous broadcast from separate locations

A videoconference meeting facilitated byGoogle Hangouts

The core technology used in a videotelephony system is digital compression of audio and video streams in real time. The hardware orsoftwarethat performs compression is called acodec(coder/decoder). Compression rates of up to 1:500 can be achieved. The resulting digital stream of 1s and 0s is subdivided into labeledpackets,which are then transmitted through adigital networkof some kind (usuallyISDNorIP).

The other components required for a videoconferencing system include:

• Video input:(PTZ/360°/Fisheye)video camera,orwebcam
• Video output:computer monitor,television,orprojector
• Audio input:microphones,CD/DVD player, cassette player, or any other source of PreAmp audio outlet.
• Audio output:usuallyloudspeakersassociated with the display device or telephone
• Data transfer:analog or digital telephone network,LAN,orInternet
• Computer:a data processing unit that ties together the other components, does the compressing and decompressing, and initiates and maintains the data linkage via the network.

There are basically three kinds of videoconferencing and videophone systems:

1. Dedicated systemshave all required components packaged into a single piece of equipment, usually a console with a high qualityremote controlledvideo camera. These cameras can be controlled at a distance to pan left and right, tilt up and down, and zoom. They became known as PTZ cameras. The console contains all electrical interfaces, the control computer, and the software or hardware-based codec. Omnidirectional microphones are connected to the console, as well as a TV monitor with loudspeakers and/or avideo projector.There are several types of dedicated videoconferencing devices:
   1. Large group videoconferencing are built-in, large, expensive devices used for large rooms such as conference rooms and auditoriums.
   2. Small group videoconferencing are either non-portable or portable, smaller, less expensive devices used for small meeting rooms.
   3. Individual videoconferencing are usually portable devices, meant for single users, and have fixed cameras, microphones, and loudspeakers integrated into the console.
2. Desktop systemsare add-ons (hardware boards or software codec) to normal PCs and laptops, transforming them into videoconferencing devices. A range of different cameras and microphones can be used with the codec, which contains the necessary codec and transmission interfaces.
3. WebRTCplatformsuse a web browser instead of dedicatednative applicationsoftware. Solutions such asAdobe ConnectandCisco WebExcan be accessed using a URL sent by the meeting organizer, and various degrees of security can be attached to the virtual room. Often the user must download and install abrowser extensionto enable access to the local camera and microphone and establish a connection to the meeting. But WebRTC does not require any special software, instead a WebRTC-compliant internet browser itself provides the facilities for 1-to-1 and 1-to-many videoconferencing calls. Several enhancements to WebRTC are provided by independent vendors.

Videoconferencing modes

Videoconferencing systems use several methods to determine which video feed or feeds to display.

Continuous Presencesimply displays all participants at the same time, usually with the exception that the viewer either does not see their own feed, or sees their own feed in miniature.

Voice-Activated Switchselectively chooses a feed to display at each endpoint, with the goal of showing the person who is currently speaking. This is done by choosing the feed (other than the viewer) which has the loudest audio input (perhaps with some filtering to avoid switching for very short-lived volume spikes). Often, if no remote parties are currently speaking, the feed with the last speaker remains on the screen.

Echo cancellation

Acoustic echo cancellation(AEC) is a processingalgorithmthat uses the knowledge of audio output to monitor audio input and filter from it noises that echo back after some time delay. If unattended, these echoes can be re-amplified several times, leading to problems including:

• The remote party hearing their own voice coming back at them (usually significantly delayed)
• Strongreverberation,which makes the voice channel useless
• Howling created by feedback

Echo cancellation is a processor-intensive task that usually works over a narrow range of sound delays.

Bandwidth requirements

Deutsche TelekomT-View 100ISDN-type videophone meant for home offices and small businesses, with a lens cover which can be rotated upward for privacy

See also:Broadband Internet access

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 progressively limited and poorer image quality (i.e. lower resolution and/or frame rate). Data transfer rates and live video image quality are related but are also subject to other factors such asdata compression techniques.Some early videophones employed very low data transmission rates with a resulting poor video quality.

Broadband bandwidthis often calledhigh-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. TheInternational Telecommunication Union Telecommunication Standardization Sector(ITU-T) recommendationI.113has defined broadband as a transmission capacity at 1.5 to 2Mbit/s. TheFederal Communications Commission(United States) definition of broadband is 25 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 videoconferencing applications, and rates as low as 100 kbit/s used for videophones usingH.264/MPEG-4 AVCcompression protocols. The newerMPEG-4videoandaudio compressionformat can deliver high-quality video at 2Mbit/s, which is at the low end ofcable modemandADSLbroadband performance.

Standards

TheTandberg E20is an example of aSIP-only device. Such devices need to route calls through a Video Communication Server to be able to reachH.323systems, a process known as "interworking" (2009).

TheInternational Telecommunication Union(ITU) has three umbrellas of standards for videoconferencing:

• ITUH.320is known as the standard forpublic switched telephone networks(PSTN) or videoconferencing over integrated services digital networks. While still prevalent in Europe,ISDNwas never widely adopted in the United States and Canada.
• ITUH.264Scalable Video Coding(SVC) is a compression standard that enables videoconferencing systems to achieve highly error resilientInternet Protocol(IP) video transmissions over the public Internet without quality-of-service enhanced lines.This standard has enabled wide scale deployment of high definition desktop videoconferencing and made possible new architectures,which reduces latency between the transmitting sources and receivers, resulting in more fluid communication without pauses. In addition, an attractive factor for IP videoconferencing is that it is easier to set up for use along withweb conferencinganddata collaboration.These combined technologies enable users to have a richermultimediaenvironment for live meetings, collaboration and presentations.
• ITU-T V.80:videoconferencing is generally compatibilized withH.324standard point-to-point videotelephony over regular (POTS) phone lines.

TheUnified Communications Interoperability Forum(UCIF), a non-profit alliance between communications vendors, launched in May 2010. The organization's vision is to maximize the interoperability of UC based on existing standards. Founding members of UCIF includeHP,Microsoft,Polycom,Logitech/Lifesize,andJuniper Networks.

Call setup

Videoconferencing in the late 20th century was limited to theH.323protocol (notably Cisco'sSCCPimplementation was an exception), but newer videophones often useSIP,which is often easier to set up in home networking environments.It is a text-based protocol, incorporating many elements of theHypertext Transfer Protocol(HTTP) and theSimple 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 oninstant messagingprotocols such asSkypealso now provide video.

Another protocol used by videophones isH.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 called3G-324Mdefined by3GPPis also used by some cellphones that allow video calls, typically for use only inUMTSnetworks.

There is alsoH.320standard, 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-bandwidthISDNdigital phone protocol or a fractionated high bandwidth T1 lines. Modern products based on H.320 standard usually support also H.323 standard.

TheIAX2protocol also supports videophone calls natively, using the protocol's own capabilities to transport alternate media streams. A few hobbyists obtained the Nortel 1535 Color SIP Videophone cheaply in 2010 as surplus afterNortel's bankruptcy and deployed the sets on theAsterisk (PBX)platform. While additional software is required to patch together multiple video feeds for conference calls or convert between dissimilar video standards, SIP calls between two identical handsets within the same PBX were relatively straightforward.

Further information:Video codec

Conferencing layers

The components within a videoconferencing system can be divided up into several different layers: User Interface, Conference Control, Control or Signaling Plane, and Media Plane.

Videoconferencing User Interfaces (VUI) can be either graphical or voice-responsive. Many in the industry have encountered both types of interface, and normally a graphical interface is encountered on a computer. User interfaces for conferencing have a number of different uses; they can be used for scheduling, setup, and making a video call. Through the user interface, the administrator is able to control the other three layers of the system.

Conference Control performs resource allocation, management, and routing. This layer along with the User Interface creates meetings (scheduled or unscheduled) or adds and removes participants from a conference.

Control (Signaling) Plane contains the stacks that signal different endpoints to create a call and/or a conference. Signals can be, but are not limited to,H.323andSession Initiation Protocol(SIP) Protocols. These signals control incoming and outgoing connections as well as session parameters.

The Media Plane controls the audio and video mi xing and streaming. This layer manages Real-Time Transport Protocols, User Datagram Packets (UDP) andReal-Time Transport Control Protocol(RTCP). The RTP and UDP normally carry information such the payload type which is the type of codec, frame rate, video size, and many others. RTCP on the other hand acts as a quality control Protocol for detecting errors during streaming.

Multipoint control

Main article:Multipoint Control Unit

Simultaneous videoconferencing among three or more remote points is possible in a hardware-based system by means of aMultipoint Control Unit(MCU). This is a bridge that interconnects calls from several sources (in a similar way to the audio conference call). All parties call the MCU, or the MCU can also call the parties which are going to participate, in sequence. There are MCU bridges for IP and ISDN-based videoconferencing. There are MCUs which are pure software and others that are a combination of hardware and software. An MCU is characterized according to the number of simultaneous calls it can handle, its ability to conduct transposing of data rates and protocols, and features such as Continuous Presence, in which multiple parties can be seen on-screen at once. MCUs can be stand-alone hardware devices, or they can be embedded into dedicated videoconferencing units.

The MCU consists of two logical components:

1. A single multipoint controller (MC), and
2. Multipoint Processors (MP), sometimes referred to as the mixer.

The MC controls the conferencing while it is active on the signaling plane, which is simply where the system manages conferencing creation, endpoint signaling and in-conferencing controls. This component negotiates parameters with every endpoint in the network and controls conferencing resources. While the MC controls resources and signaling negotiations, the MP operates on the media plane and receives media from each endpoint. The MP generates output streams from each endpoint and redirects the information to other endpoints in the conference.

Some systems are capable of multipoint conferencing with no MCU, stand-alone, embedded or otherwise. These use a standards-based H.323 technique known asdecentralized multipoint,where each station in a multipoint call exchanges video and audio directly with the other stations with no centralmanageror other bottleneck. The advantages of this technique are that the video and audio will generally be of higher quality because they do not have to be relayed through a central point. Also, users can make ad hoc multipoint calls without any concern for the availability or control of an MCU. This added convenience and quality comes at the expense of some increased network bandwidth, because every station must transmit to every other station directly.

Cloud storage

Cloud-based videoconferencing can be used without the hardware generally required by other videoconferencing systems, and can be designed for use bySMEs,or larger international or multinational corporations likeFacebook.Cloud-based systems can handle either 2D or 3D video broadcasting.Cloud-based systems can also implement mobile calls, VOIP, and other forms of video calling. They can also come with a video recording function to archive past meetings.

Impact

A mobile video call betweenSwedenandSingaporemade on aSony EricssonK800(2007)

High speed Internet connectivity has become more widely available and affordable, as has good-quality video capture and display hardware. Consequently, personal videoconferencing systems based on webcams, personal computer systems, software compression, and the Internet have become progressively more affordable by the general public. The availability of freeware (often as part ofchat programs) has made software based videoconferencing accessible to many.

The widest deployment of videotelephony now occurs inmobile phones.Nearly all mobile phones supportingUMTSnetworks can work as videophones using their internal cameras and are able to make video calls wirelessly to other UMTS users anywhere.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.Mobile phones can also use broadband wireless Internet, whether through the cell phone network or over a localWi-Ficonnection, along with software-based videophone apps to make calls to any video-capable Internet user, whether mobile or fixed.

Deaf, hard-of-hearing,andmuteindividuals have a particular role in the development of affordable high-quality videotelephony as a means of communicating with each other insign language.UnlikeVideo Relay Service,which is intended to support communication between a caller using sign language and another party using spoken language, videoconferencing can be used directly between two deaf signers.

Videophones are increasingly used in the provision oftelemedicineto the elderly, disabled, 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 60pensionersto be assessed by medics without traveling 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 asblood sugarlevel,blood pressure,andvital signsmonitoring. Such units are capable of relaying both regular audio-video plus medical data over either standard (POTS) telephone or newerbroadbandlines.

A Tandberg T3 high-resolution telepresence room in use (2008)

Videotelephony has also been deployed in corporateteleconferencing,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 calledtelepresence.

Today the principles, if not the precise mechanisms, of a videophone are employed by many users worldwide in the form ofwebcamvideocalls using personal computers, with inexpensive webcams, microphones, and free video callingWeb clientprograms. 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.

A study conducted by Pew Research in 2010, revealed that 7% of Americans have made a mobile video call.

Government and law

In the United States, videoconferencing has allowed testimony to be used for an individual who is unable or prefers not to attend the physical legal settings or would be subjected to severe psychological stress in doing so, however, there is a controversy on the use of testimony by foreign or unavailable witnesses via video transmission, regarding the violation of theConfrontation Clause of the Sixth Amendmentof the U.S. Constitution.

In a military investigation inNorth Carolina,Afghanwitnesses have testified via videoconferencing.

InHall County, Georgia,videoconferencing systems are used for initial court appearances. The systems link jails with courtrooms, reducing the expenses and security risks of transporting prisoners to the courtroom.

TheU.S. Social Security Administration(SSA), which oversees the world's largest administrative judicial system under itsOffice of Disability Adjudication and Review(ODAR),has made extensive use of videoconferencing to conduct hearings at remote locations.In Fiscal Year (FY) 2009, the U.S. Social Security Administration (SSA) conducted 86,320 videoconferenced hearings, a 55% increase over FY 2008.In August 2010, the SSA opened its fifth and largest videoconferencing-only National Hearing Center (NHC), inSt. Louis,Missouri.This continues the SSA's effort to use video hearings as a means to clear its substantial hearing backlog. Since 2007, the SSA has also established NHCs inAlbuquerque,New Mexico,Baltimore,Maryland,Falls Church,Virginia,andChicago.

Education

Indonesian and U.S. students participate in an educational videoconference (2010)

See also:Distance education

Videoconferencing provides students with the chance to learn by participating in two-way communication forums. Because it is live, videotelephony allows teachers to access remote or otherwise isolated learners. Students from diverse communities and backgrounds can come together to learn about one another through practices known astelecollaboration(in foreign language education) andvirtual exchange,althoughlanguage barrierswill continue to be present. Such students are able to explore, communicate, analyze, and share information and ideas with one another.

Through videoconferencing, students can visit other parts of the world, including museums and other cultural and educational sites. Suchvirtual field tripscan provide enriched learning opportunities to students, especially those who are geographically isolated or economically disadvantaged. Small schools can use these technologies to pool resources and provide courses, such as in foreign languages, which could not otherwise be offered.

Some benefits that videoconferencing can provide to education include:

• faculty members keeping in touch with classes while attending conferences;
• faculty members attending conferences 'virtually'
• guest lecturers brought in classes from other institutions;
• researchers collaborating with colleagues at other institutions on a regular basis without loss of time due to travel;
• schools with multiple campuses collaborating and sharing professors;
• schools from two separate nations engaging incross-cultural exchanges;
• faculty members participating in thesis defenses at other institutions;
• administrators on tight schedules collaborating on budget preparation from different parts of campus;
• faculty committee auditioning scholarship candidates;
• researchers answering questions about grant proposals from agencies or review committees;
• alternative enrollment structures to purely in-person attendance;
• student interviews with employers in other cities, and
• teleseminars.

Medicine and health

Main article:Telemedicine

Videoconferencing is a highly useful technology for real timetelemedicineandtelenursingapplications, such asdiagnosis,consulting, prevention, treatment, and transmission ofmedical images.With videoconferencing, patients may contactnursesandphysiciansinemergencyor routine situations; physicians and otherparamedicalprofessionals can discuss cases across large distances. Rural areas can use this technology for diagnostic purposes, thus saving lives and making more efficient use of health care money. For example, a rural medical center inOhioused videoconferencing to successfully cut the number of transfers of sick infants to ahospital70 miles (110 km) away. This had previously cost nearly $10,000 per transfer.

Special peripherals such asmicroscopesfitted withdigital cameras,videoendoscopes,medical ultrasoundimaging devices,otoscopes,etc., can be used in conjunction with videoconferencing equipment to transmit data about a patient. Recent developments inmobile collaborationon hand-held mobile devices have also extended video-conferencing capabilities to locations previously unreachable, such as a remote community, long-term care facility, or a patient's home.

Business

Videoconferencing can enable individuals in distant locations to participate in meetings on short notice, with time and money savings. Technology such asVoIPcan be used in conjunction with desktop videoconferencing to enable low-cost face-to-face business meetings without leaving the desk, especially for businesses with widespread offices. The technology is also used forremote work.One research report based on a sampling of 1,800 corporate employees showed that, as of June 2010, 54% of the respondents with access to videoconferencing used it "all of the time" or "frequently".

Intel Corporation have used videoconferencing to reduce both costs and environmental impacts of its business operations.

Videoconferencing is also currently being introduced on online networking websites, in order to help businesses form profitable relationships quickly and efficiently without leaving their place of work. This has been leveraged by banks to connect busy banking professionals with customers in various locations usingvideo bankingtechnology.

Videoconferencing on hand-held mobile devices (mobile collaborationtechnology) is being used in industries such as manufacturing, energy, healthcare, insurance, government, and public safety. Live, visual interaction removes traditional restrictions of distance and time, often in locations previously unreachable, such as a manufacturing plant floor thousands of miles away.

In the increasinglyglobalizedfilm industry,videoconferencing has become useful as a method by which creative talent in many different locations can collaborate closely on the complex details of film production. For example, for the 2013 award-winning animated filmFrozen,Burbank-basedWalt Disney Animation Studioshired theNew York City-based husband-and-wife songwriting team ofRobert LopezandKristen Anderson-Lopezto write the songs, which required two-hour-long transcontinental videoconferences nearly every weekday for about 14 months.

With the development of lower-cost endpoints, the integration of video cameras into personal computers and mobile devices, and software applications such asFaceTime,Skype,Teams,BlueJeansand Zoom, videoconferencing has changed from just a business-to-business offering to include business-to-consumer (and consumer-to-consumer) use.

Although videoconferencing has frequently proven its value, research has shown that some non-managerial employees prefer not to use it due to several factors, including anxiety.Some such anxieties can often be avoided if managers use the technology as part of the normal course of business. Remote workers can also adopt certain behaviors and best practices to stay connected with their co-workers and company.

Researchers also find that attendees of business and medical videoconferences must work harder to interpret information delivered during a conference than they would if they attended face-to-face.They recommend that those coordinating videoconferences make adjustments to their conferencing procedures and equipment.

Press

Main article:Press videoconferencing

The concept ofpress videoconferencingwas developed in October 2007 by the PanAfrican Press Association (APPA), a Paris France-basednon-governmental organization,to allow African journalists to participate in internationalpress conferenceson developmental andgood governanceissues.

Press videoconferencing permits international press conferences via videoconferencing over the Internet. Journalists can participate on an international press conference from any location, without leaving their offices or countries. They need only be seated by a computer connected to the Internet in order to ask their questions.

In 2004, theInternational Monetary Fundintroduced the Online Media Briefing Center, a password-protected site available only to professional journalists. The site enables the IMF to present press briefings globally and facilitates direct questions to briefers from the press. The site has been copied by other international organizations since its inception. More than 4,000 journalists worldwide are currently registered with the IMF.

Sign language

Video Interpreter sign used at VRS/VRI service locations

Main articles:Video Relay ServiceandVideo Remote Interpreting

One of the first demonstrations of the ability fortelecommunicationsto help sign language users communicate with each other occurred whenAT&T'svideophone(trademarked as thePicturephone) was introduced to the public at the1964 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, includingBritish Telecom's Martleshamfacility, have also conducted extensive research onsigningvia video telephony.

The use of sign language via videotelephony was hampered for many years due to the difficulty of its use over slowanalog copper phone lines,coupled with the high cost of better qualityISDN (data) phone lines.Those factors largely disappeared with the introduction of more efficient and powerfulvideo codecsand the advent of lower-cost high-speed ISDN data and IP (Internet) services in the 1990s.

21st-century improvements

Significant improvements in video call quality of service for the deaf occurred in the United States in 2003 whenSorenson Media Inc.(formerly Sorenson Vision Inc.), a video compression software coding company, developed its VP-100 model stand-alonevideophonespecifically 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 powerfulvideo compression codecfor unequaled video quality and ease of use with video relay services. Favorable 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, theavailability of high-speed Internet,andsponsored video relay servicesauthorized by the U.S.Federal Communications Commissionin 2002, VRS services for the deaf underwent rapid growth in that country.

A deaf or hard-of-hearing person uses a Video Relay Service at his workplace to communicate with a hearing person in London (2007).

Using such video equipment in the present day, the deaf, hard-of-hearing, and speech-impaired can communicate between themselves and with hearing individuals usingsign 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 viaVideo Remote Interpreting(VRI). The relatively low cost and widespread availability of3Gmobile phonetechnology 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 isdeaf,hard-of-hearing,orspeech-impaired (mute).In such cases the interpretation flow is normally within the same principal language, such asFrench Sign Language(LSF) to spoken French,Spanish Sign Language(LSE) to spoken Spanish,British Sign Language(BSL) to spoken English, andAmerican Sign Language(ASL) also to spoken English (since BSL and ASL are completely distinct from each other),German Sign Language(DGS) to spoken German, and so on.

Multilingualsign language interpreters,who can also translate as well across principal languages (such as a multilingual interpreter interpreting a call from a deaf person using ASL to reserve a hotel room at a hotel in theDominican Republicwhose staff speaks Spanish only, therefore the interpreter has to use ASL, spoken Spanish, and spoken English to facilitate the call for the deaf person), are also available, albeit less frequently. Such activities involve considerable mental processing efforts on the part of the translator, since sign languages are distinctnatural languageswith their ownconstruction,semanticsandsyntax,different from the aural version of the same principal language.

With video interpreting,sign languageinterpreters work remotely with livevideoand audio feeds, so that the interpreter can see the deaf or mute party, and converse with the hearing party, and vice versa. Much liketelephone interpreting,video interpreting can be used for situations in which no on-siteinterpretersare 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 thenecessary equipment.Some advanced equipment enables interpreters to control the video camera remotely, in order tozoomin and out or to point the camera toward the party that is signing.

Comparison of Sign Language communication tools

Tool	Owner	Free?	Pure web based?	Works on desktops?	Mobile support?	Uses email?	Required hardware	Installation	Limitations	Specialities	Technologies	Deaf made?	Licensing
Facebook Messenger	Facebook	Yes	No	Yes	Yes	No	Any mobile	App must be installed, does not require a Facebook account			?	No	100% proprietary
FaceTime	Apple Inc.	Yes	No	Yes	Yes	No	Apple hardware only (Desktopor mobile)	App must be installed, requires an Apple ID account			?	No	100% proprietary
Glide (software)	Glide	Yes	No	No	Yes	No	Any mobiles	App must be installed			?	No	100% proprietary
Google Hangouts	Google	Yes	No	Yes	Yes	No	AnyDesktopor mobiles	App must be installed, requires a Google account			?	No	100% proprietary
Skype	Microsoft	Yes	No	Yes	Yes	No	AnyDesktopor mobile	App must be installed, requires a Microsoft account			?	No	100% proprietary
TikatoyArchived2019-01-08 at theWayback Machine	TikatoyArchived2019-01-08 at theWayback Machine	Yes	No	Yes	Androidonly	Yes	DesktoporAndroid	Requires a web browser withAdobe Flash	Apple blocksAdobe Flash		C++,JavaScript,Python	Yes	100% proprietary
videomail.io	Binary Kitchen	Yes	Yes	Yes	Androidonly	Yes	DesktoporAndroid,iPhoneandSafarionly for viewing	Web browser	Recording max 3 minutes, does not work on old browsers	Reusable: can be plugged directly into other websites or as a WordPress pluginninja-forms-videomailArchived2018-01-19 at theWayback Machine	JavaScript	Yes	Mixed. Proprietary server and client is open source

Descriptive names and terminology

See also:List of video telecommunication services and product brands

The namevideophonenever became as standardized as its earlier counterparttelephone,resulting in a variety of names and terms being used worldwide, and even within the same region or country. Videophones are also known asvideo phones,videotelephones(orvideo telephones) and often by an early trademarked namePicturephone,which was the world's first commercial videophone produced in volume. The compound namevideophoneslowly entered into general use after 1950, althoughvideo telephonelikely entered the lexicon earlier aftervideowas coined in 1935.

Videophone calls(also:videocalls,video chat)as well asSkypeandSkypingin verb formdiffer from videoconferencing in that they expect to serve individuals, not groups.However that distinction has become increasingly blurred with technology improvements such asincreased bandwidthand sophisticatedsoftware clientsthat can allow for multiple parties on a call. In general everyday usage the termvideoconferencingis now frequently used instead ofvideocallfor point-to-point calls between two units. Both videophone calls and videoconferencing are also now commonly referred to as avideo link.

Webcamsare popular, relatively low-cost devices that can provide live video and audio streams via personal computers, and can be used with manysoftware clientsfor both video calls and videoconferencing.

Avideoconference systemis generally higher cost than a videophone and deploys greater capabilities. Avideoconference(also known as avideoteleconference) allows two or more locations to communicate via live, simultaneous two-way video and audio transmissions. This is often accomplished by the use of amultipoint 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.

Atelepresence systemis a high-end videoconferencing system and service usually employed byenterprise-levelcorporate 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 uses of the various technologies described above include calling one-to-one or conferencing one-to-many or many-to-many for personal, business, educational,deaf Video Relay Serviceandtele-medical, diagnosticandrehabilitativepurposes.personal videocalls toinmates incarcerated in penitentiaries,and videoconferencing to resolveairline engineering issuesatmaintenance facilities,are being created or evolving on an ongoing basis.

Other names forvideophonethat have been used in English are:Viewphone(theBritish Telecomequivalent toAT&T's Picturephone),andvisiophone,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 ofvideophonein other languages includevidéophone(French),Bildtelefon(German),videotelefono(Italian), bothvideófonoandvideoteléfono(Spanish), bothbeeldtelefoonandvideofoon(Dutch), andvideofonía(Catalan).

Atelepresence robot(alsotelerobotics) is a robotically controlled and motorized videoconferencing display to help give a better sense of remote physical presence for communication and collaboration in an office, home, school, etc. when one cannot be there in person. The robotic avatar device can move about and look around at the command of the remote person it represents.

Popular culture

Dr. Heywood Floyd in the 1968 film2001: A Space Odysseycalls his daughter on Earth.

Inscience fictionliterature, names commonly associated with videophones includetelephonoscope,telephote,viewphone,vidphone,vidfone,andvisiphone.The first example was probably the cartoon "Edison's Telephonoscope" by George du Maurier inPunch1878.In «In the year 2889», published 1889, the French author Jules Verne predicts that «The transmission of speech is an old story; the transmission of images by means of sensitive mirrors connected by wires is a thing but of yesterday.»In manyscience fictionmoviesand TV programs that are set in the future, videophones were used as a primary method of communication. One of the first movies where a videophone was used wasFritz Lang'sMetropolis(1927).

Other notable examples of videophones in popular culture include an iconic scene from the 1968 film2001: A Space Odysseyset onSpace Station V.The movie was released shortly before AT&T began its efforts to commercialize its Picturephone Mod II service in several cities and depicts a video call to Earth using an advanced AT&T videophone—which it predicts will cost $1.70 for a two-minute call in 2001 (a fraction of the company's real rates on Earth in 1968). Film directorStanley Kubrickstrove for scientific accuracy, relying on interviews with scientists and engineers atBell Labsin the United States. Dr.Larry Rabinerof Bell Labs, discussing videophone research in the documentary2001: The Making of a Myth,stated that in the mid-to late-1960s videophones "...captured the imagination of the public and... of Mr. Kubrick and the people who reported to him ". In one2001movie scene a central character, Dr. Heywood Floyd, calls home to contact his family, a social feature noted in theMaking of a Myth.Floyd talks with and views his daughter from aspace stationinorbit above the Earth,discussing what type of present he should bring home for her.

Other earlier examples of videophones in popular culture included a videophone that was featured in theWarner Bros.cartoon,Plane Daffy,in which the female spyHatta Mariused a videophone to communicate withAdolf Hitler(1944), as well as a device with the same functionality has been used by the comic strip characterDick Tracy,who often used his "2-way wrist TV" 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 used videophones to interview subjects of interest and to present live coverage by news correspondents, via the Internet or by satellite links. In the mass market media, the popular U.S.TV talk showhostessOprah Winfreyincorporated videotelephony into her TV program on a regular basis from May 21, 2009, with an initial episode calledWhere the Skype Are You?,as part of a marketing agreement with the Internet telecommunication companySkype.

See also

• 3GP and 3G2
• Comparison of web conferencing software
• List of video telecommunication services and product brands
• Media phone
• Mobile VoIP
• Project DIANE—a large U.S. business and social services videoconferencing network
• Teletraining
• U.S.–Soviet Space Bridge
• Visual communication

Bibliography

• Santanu Brahma & Axlator CommunicationsAudio Video TelephonyArchived2021-01-19 at theWayback Machine,Real time updates and news about WebRTC technology and browser-based audio and videotelephony.
• Burns, R.W.,Television:An International History of the Formative Yearsin IEE Publication Series,Institution of Electrical Engineers,Science Museum(Great Britain), 1998,ISBN0-85296-914-7,ISBN978-0-85296-914-4
• Daly, Edward A. & Hansell, Kathleen J.Visual Telephony,Artech House, Boston, 1999,ISBN1-58053-023-0,ISBN978-1-58053-023-1,CIPD HD9697.T452D35 651.7'3-dc21.
• Mulbach, Lothar; Bocker, Martin; Prussog, Angela (1995). "Telepresence in Videocommunications: A Study on Stereoscopy and Individual Eye Contact".Human Factors.37(2): 290–305.doi:10.1518/001872095779064582.ISSN0018-7208.PMID7642183.S2CID31369406.
• Nellist, John G.Understanding Telecommunications And Lightwave Systems: An Entry-Level Guide,John Wiley and Sons, IEEE Press, 2002,ISBN0-471-15032-0,ISBN978-0-471-15032-9.
• Schnaars, Steve; Wymbs, Cliff (2004). "On The Persistence Of Lackluster Demand—The History Of The Video Telephone".Technological Forecasting and Social Change.71(3): 197–216.doi:10.1016/S0040-1625(02)00410-9.
• Shepard, Steven.Videoconferencing Demystified: Making Video Services Work,McGraw-Hill Professional, 2002,ISBN0-07-140085-0,ISBN978-0-07-140085-5
• Stevenson Bacon, W.Amazing New Picturephone: A Step Closer to In-Person Visits,Popular Science,June 1968, pp. 46–47.
• Valinder, Anne.Like a window in your living room: Video-mediated communication for extended families separated by space,University of Gothenburg: Department of Applied Information Technology, pp. 6–18, October 5, 2012. Web. January 23, 2013 (PDF).
• Wilcox, James R. & Gibson, David K.Video Communications: The Whole Picture,Focal Press, CMP Books, San Francisco, 2005,ISBN1-57820-316-3,ISBN978-1-57820-316-1.

Further reading

Unsorted

• Greenberg, Alan D.Taking the Wraps off Videoconferencing in the US Classroom,Wainhouse Research, April 2009.
• Kopytoff, Verne G.Hewlett-Packard Sells Its Video Conferencing Business,The New York Times,June 1, 2011.
• Lawlor, Julia.Videoconferencing: From Stage Fright to Stage Presence,The New York Times,August 27, 1998.
• Lohr, Steve.As Travel Costs Rise, More Meetings Go Virtual,The New York Times,July 22, 2008.
• Miller, Claire Cain.Logitech Buying a Maker Of Videoconference Tools,The New York Times,November 11, 2009.
• Miller, Claire Cain.Logitech Breaks Into Videoconferencing,The New York Times,November 10, 2009 on line, and November 11, 2009, in print, p. B3. Discusses the acquisition of LifeSize Communications.
• Millman, Howard.The Videoconference as a Bicoastal Pas de Deux,The New York Times,July 12, 2001.
• O'Brien, Kevin.Stranded Travelers Turn to Videoconferencing,The New York Times,April 19, 2010. Article discusses the increased use of videoconferencing due to the eruption of an Icelandic volcano which severely curtailed air travel for several months.
• Ramirez, Anthony.More Than Just a Phone Call; Video Conferencing And Photocopies, Too,The New York Times,September 15, 1993. Discusses the deployment of videoconferencing rooms in several hundredKinkoslocations.
• Shannon, Victoria.Videoconferencing's virtual leap forward,The New York Times,August 29, 2007.
• Sharkey, Joe.A Meeting in New York? Can't We Videoconference?,The New York Times,May 11, 2009 online, and in print on May 12, 2009, p. B6 of the New York edition.
• Vance, Ashlee.Cisco Buys Norwegian Firm for $3 Billion,The New York Times,October 1, 2009 online, and October 2, 2009, in print, p. B7. Discusses the acquisition ofTandberg.
• Wang, SesOpen source tool detects videoconferencing equipment vulnerabilities,Help Net Security, 17 February 2012.
• Wayner, Peter.Jerky Pictures and Sound Are History. Videoconferencing Is All Grown Up.,The New York Times,June 16, 2005.

General

• Adeshina, Emmanuel.In-Person Visits Fade as Jails Set Up Video Units for Inmates and Families,The New York Timeswebsite, August 7, 2012, pg. A15 of the New York Edition.
• 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.
• Fairlie, Rik.Skype Puts Video Calls on Your TV,The New York Times,July 2, 2010.
• 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 nytimes.
• Miller, Hugh."Videophones: The Real Problem".Archived from the original on 2002-06-16.Retrieved2002-06-16.{{cite web}}:CS1 maint: bot: original URL status unknown (link),Department of Social Sciences,Nottingham Trent University,June 16, 2002. Discusses social issues related to videotelephony.
• Perlroth, Nicole.Cameras May Open Up the Board Room to Hackers,The New York Times online,January 22, 2012. A version of this article appeared in print on January 23, 2012, on page B1 of the New York edition with the headline: "Conferences Via the Net Called Risky".
• ProAV Magazine.Being There,ProAV Magazine,November 7, 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?,Forbeswebsite, October 15, 2007

Environmental benefits

• Biello, David.Can Videoconferencing Replace Travel?,Scientific American,March 18, 2009.
• Coroama, V.C., et al.Effects of Internet-Based Multiple-Site Conferences on Greenhouse Gas EmissionsArchived2013-06-03 at theWayback Machine,Telematics and Informatics,2011, doi:10.1016/j.tele.2011.11.006
• Pachner, Joanna.The Next Best Thing to Being There,Toronto:The Globe and Mail,October 13, 2009.

Historical and technical

• Ebel, H. "Subjective Assessment of Picture Interference in the Videophone" in4th International Symposium on Human Factors in Telephony,Bad Wiessee, Germany, September 23–27, 1968, Information Gatekeepers Inc., pp. 289–298.
• Fischer, K.; Ebel, H.; "Problems Of How To Position Users In Front Of The Videophone" in:4th International Symposium on Human Factors in Telephony,Bad Wiessee, Germany, September 23–27, 1968, Information Gatekeepers Inc., pp. 269–282.
• Hall, A.D. "Experiments with Picturephone Service" in:Bell Laboratories RECORD,1964, Vol. 42, pp. 114–120.
• Ives, Herbert E.Two-Way Television and a Pictorial Account of its Backgroundin:Bell Laboratories Record,1930, Vol. 8, pp. 399–404, andviewable online hereArchived2020-02-05 at theWayback Machine.
• Ives, Herbert E.Picture Transmission and Televisionin:Bell Labs Quarterly,April 1932, Vol. 11, pp. 118–142.
• Jaur, Francis. "Usage Domestiques du Visiophone", Technologies de l'Information et Société, 2, 1990, pp. 89–102. (French)
• Schunack, Von Johannes; Maly, Rolf.Die Fernseh-Sprechtechnikin:Fernseh A.G.: 10 Jahre,Berlin: Hausmitteilungen Aus Forshunsg Und Betrieb Der Fernseh Aktiengellschaft, July 1939, pp. 138–143. (PDF, German)
• Schulte, Olaf A."The Next Best Thing To Being There" —Ein Überblick Zu 25 Jahren Videokonferenzforschung(An Overview of 25 years of videoconferencing research) in:Medien & Kommunikations-wissenschaft,Baden-Baden:Hans-Bredow-Institut,April 2002, pp. 551–570 (PDF, German).

External links

• Debut of the First Picturephone,1970 video courtesy of AT&T Archives and History Center, Warren, N.J.
• British Pathé news clip: Videophone 1970,a movie reel news clip on the assembly and demonstration of a prototype British General Post Office 'Viewphone' at Taplow, Buckinghamshire; (February 1, 1970; video, 1:16 seconds length)
• Whirlpool Forums: Movies that feature videophones