Videotelephonywikipedia
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.
videoconferencingvideo conferencingvideo chatvideophonevideoconferencevideo callingvideo conferencevideotelephonyvideo callvideo link

Skype

SkypeSkypingSkypes
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

telepresencetelepresence 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

CCTVclosed-circuit televisionsecurity camera
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

telemedicinetele-medicinetele-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.

Smartphone

smartphonesmartphonessmart phone
More popular videotelephony technologies use the Internet rather than the traditional landline phone network, even accounting for modern digital packetized phone network protocols, and even though videotelephony software commonly runs on smartphones.
Today, smartphones largely fulfil their users' needs for a microphone (smartphones often have one to four microphones), a digital camera (most smartphones are made with one front-facing and one to three rear-facing integrated digital cameras), a communications device (smartphones can transmit online chat, e-mails, telephone calls and video chat through the Internet by Wi-Fi as well as mobile broadband; a smartphone uses its camera in video chat, as well as its microphone in video chat and telephone calls), a handheld audio recorder (using the microphone), a satellite navigation system and trip planner, weather forecasting, a media player, a clock, news, a calculator, a web browser, a video game player, a flashlight (smartphones may possess one to two LEDs for illumination and photographic flash needs), a compass (smartphones that contain built-in magnetometers are able to function as a compass), an address book, a note creator, an event calendar, etc. Some apps allow sending and receiving facsimile (fax) over a smartphone, including raster facsimile data generated directly and digitally from document and image file formats.

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.

Codec

codeccodecsdecoder
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.

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.

CU-SeeMe

Tim DorcyCUseeME
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 video telecommsoftware clientsspecial videophonesnecessary 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.

Telephone

telephonephonetelephones
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.

Mobile collaboration

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.

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.

Slow-scan television

slow-scan televisionslow-scan TVSSTV
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.

Integrated Services Digital Network

ISDNintegrated services digital network ISDN
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.

Webcam

webcamwebcamsweb camera
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.

Internet access

broadband internetbroadbandbroadband Internet access
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 codec

video codeccodecvideo decoding
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.

H.323

RASH.323
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 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.

UMTS

UMTSWCDMA3G
In the present day standalone videophones and UMTS video-enabled mobile phones are usually used on a person-to-person basis.
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.

Multipoint control unit

multipoint control unitMCUMCUs
Simultaneous videoconferencing among three or more remote points is possible in a hardware-based system by means of a Multipoint Control Unit (MCU).
A multipoint control unit (MCU) is a device commonly used to bridge videoconferencing connections.

Video relay service

video relay servicesponsored video relay servicesdeaf Video Relay Service
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.

Instant messaging

instant messagingIMinstant messenger
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

webinarweb conferencingwebinars
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.