Videotelephony

videoconferencingvideo conferencingvideo chatvideophonevideoconferencevideo callingvideo conferencevideo callvideo linkvideo-conferencing
Videotelephony comprises the technologies for the reception and transmission of audio-video signals by users at different locations, for communication between people in real-time.wikipedia
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Skype

SkypingSkype PreviewMicrosoft Skype
News media organizations have begun to use desktop technologies like Skype to provide higher-quality audio than the phone network, and video links at much lower cost than sending professional equipment or using a professional studio. A number of call-setup methods based on instant messaging protocols such as Skype also now provide video.
Skype is a telecommunications application software product that specializes in providing video chat and voice calls between computers, tablets, mobile devices, the Xbox One console, and smartwatches via the Internet and to regular telephones.

Telepresence

immersiontelepresence systemtelepresence technology
Telepresence may refer either to a high-quality videotelephony system (where the goal is to create the illusion that remote participants are in the same room) or to meetup technology, which goes beyond video into robotics (such as moving around the room or physically manipulating objects).
A popular application is found in telepresence videoconferencing, the highest possible level of videotelephony.

Closed-circuit television

CCTVsecurity cameravideo surveillance
Such an antecedent usually consisted of two closed-circuit television systems connected via coax cable or radio.
Though Videotelephony is seldom called 'CCTV' one exception is the use of video in distance education, where it is an important tool.

Telemedicine

tele-medicinetelemedicaltele-medical, diagnostic
Although not as widely used in everyday communications as audio-only and text communication, useful applications include sign language transmission for deaf and speech-impaired people, distance education, telemedicine, and overcoming mobility issues.
Early forms of telemedicine achieved with telephone and radio have been supplemented with videotelephony, advanced diagnostic methods supported by distributed client/server applications, and additionally with telemedical devices to support in-home care.

Project DIANE

Over the next 15 years, Project DIANE (Diversified Information and Assistance Network) grew to utilize 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.
Project DIANE, an acronym for Diversified Information and Assistance NEtwork, was a very early videoconferencing based community service network created in the United States.

Telephone

phonetelephonesLocal Telephone Service
A videophone is a telephone with a video display, capable of simultaneous video and audio for communication between people in real-time.
They may be able to record spoken messages, send and receive text messages, take and display photographs or video, play music or games, surf the Internet, do road navigation or immerse the user in virtual reality.

PictureTel Corp.

PictureTelPictureTel Corporation
One of the first commercial videoconferencing systems sold to companies came from PictureTel Corp., which had an Initial Public Offering in November, 1984.
PictureTel Corporation, often shortened to PictureTel Corp., was one of the first commercial videoconferencing product companies.

Codec

codecsdecoderdecoders
The development of advanced video codecs, more powerful CPUs, and high-bandwidth Internet telecommunication services in the late 1990s allowed videophones to provide high quality low-cost colour service between users almost anyplace in the world that the Internet is available.
Codecs are used in videoconferencing, streaming media, and video editing applications.

CU-SeeMe

CUseeMETim Dorcy
In 1992 CU-SeeMe was developed at Cornell by Tim Dorcey et al. In 1995 the first public videoconference between North America and Africa took place, linking a technofair in San Francisco with a techno-rave and cyberdeli in Cape Town.
CU-SeeMe (also written as CUseeMe or CUSeeMe depending on the source) is an Internet videoconferencing client.

List of video telecommunication services and product brands

List of vpopular instant messaging programsList ofirst sectionnecessary equipment
Webcams are popular, relatively low cost devices which can provide live video and audio streams via personal computers, and can be used with many [[List of video telecommunication services and product brands#Software Client brands|software clients]] for both video calls and videoconferencing.
This list of video telecommunication services and product brands is for groupings of notable video telecommunication services, brands of videophones, webcams and video conferencing hardware and systems, all related to videotelephony for two-way communications with live video and audio.

Mobile collaboration

Mobile collaboration systems now allow people in previously unreachable locations, such as workers on an off-shore oil rig, the ability to view and discuss issues with colleagues thousands of miles away.
Differing from traditional video conferencing, mobile collaboration utilizes wireless, cellular and broadband technologies enabling effective collaboration independent of location.

Slow-scan television

slow-scan TVSSTVslow scan
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.
Vostok was based on an earlier videophone project which used two cameras, with persistent LI-23 iconoscope tubes.

Webcam

webcamsweb cameraweb cam
Webcams are popular, relatively low cost devices which can provide live video and audio streams via personal computers, and can be used with many [[List of video telecommunication services and product brands#Software Client brands|software clients]] for both video calls and videoconferencing. With the rapid improvements and popularity of the Internet, videotelephony has become widespread through the deployment of video-enabled mobile phones, plus videoconferencing and computer webcams which utilize Internet telephony.
Webcams are known for their low manufacturing cost and their high flexibility, making them the lowest-cost form of videotelephony.

H.323

RAS
5) Desktop systems are 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. Most of the desktops systems work with the H.323 standard.
It is widely implemented by voice and videoconferencing equipment manufacturers, is used within various Internet real-time applications such as GnuGK and NetMeeting and is widely deployed worldwide by service providers and enterprises for both voice and video services over IP networks.

Video codec

codecvideo decodingcodecs
Only in the late 20th century with the advent of powerful video codecs combined with high-speed Internet broadband and ISDN service did videotelephony become a practical technology for regular use.
Video codecs are used in DVD players, Internet video, video on demand, digital cable, digital terrestrial television, videotelephony and a variety of other applications.

UMTS

WCDMA3GUniversal Mobile Telecommunications System
In the present day standalone videophones and UMTS video-enabled mobile phones are usually used on a person-to-person basis. A slightly modified version of H.324 called 3G-324M defined by 3GPP is also used by some cellphones that allow video calls, typically for use only in UMTS networks.
The first national consumer UMTS networks launched in 2002 with a heavy emphasis on telco-provided mobile applications such as mobile TV and video calling.

Integrated Services Digital Network

ISDN ISDNISDN30
Only in the late 20th century with the advent of powerful video codecs combined with high-speed Internet broadband and ISDN service did videotelephony become a practical technology for regular use.
In a videoconference, ISDN provides simultaneous voice, video, and text transmission between individual desktop videoconferencing systems and group (room) videoconferencing systems.

Video relay service

sponsored video relay servicesdeaf Video Relay Servicetranslation services
Unlike Video 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.
A video relay service (VRS), also sometimes known as a video interpreting service (VIS), is a video telecommunication service that allows deaf, hard-of-hearing, and speech-impaired (D-HOH-SI) individuals to communicate over video telephones and similar technologies with hearing people in real-time, via a sign language interpreter.

Lifesize

LifeSize Communications
In May 2005, the first high definition video conferencing systems, produced by LifeSize Communications, were displayed at the Interop trade show in Las Vegas, Nevada, able to provide video at 30 frames per second with a 1280 by 720 display resolution.
Lifesize is a video and audio telecommunications company in the United States which provides high definition videoconferencing endpoints and accessories, touchscreen conference room phones and a cloud-based video collaboration platform.

Multipoint control unit

MCUMCUs
Videoconferencing systems – midrange cost, usually utilizing multipoint control units or other bridging services to allow multiple parties on a videoconference calls. Quality of service can vary from moderate to high.
A multipoint control unit (MCU) is a device commonly used to bridge videoconferencing connections.

Instant messaging

instant messengerIMinstant message
A number of call-setup methods based on instant messaging protocols such as Skype also now provide video.
More advanced instant messaging can add file transfer, clickable hyperlinks, Voice over IP, or video chat.

Web conferencing

webinarwebinarsonline conferencing
ITU H.264 Scalable Video Coding (SVC) is a compression standard that enables videoconferencing systems to achieve highly error resilient Internet 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 with web conferencing and data collaboration. These combined technologies enable users to have a richer multimedia environment for live meetings, collaboration and presentations.
It offers data streams of text-based messages, voice and video chat to be shared simultaneously, across geographically dispersed locations.

MPEG-4

MPEG44MP4
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.
Uses of MPEG-4 include compression of AV data for web (streaming media) and CD distribution, voice (telephone, videophone) and broadcast television applications.

Distance education

distance learningcorrespondence courseonline education
Although not as widely used in everyday communications as audio-only and text communication, useful applications include sign language transmission for deaf and speech-impaired people, distance education, telemedicine, and overcoming mobility issues.
Web conferencing, videoconferencing, educational television, instructional television are examples of synchronous technology, as are direct-broadcast satellite (DBS), internet radio, live streaming, telephone, and web-based VoIP.

3G-324M

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.
3G-324M is the 3GPP umbrella protocol for video telephony in 3G mobile networks.