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What does ISDN mean?  What is a codec?  What is telepresence?  See below for answers to these and more.

128kbs, 256kbs, 384kbs, 512kbs, 768kbs

Kbs or kbps means kilobyte per second. The numbers indicate the connection speed or bandwidth that a facility’s equipment is capable of supporting. To increase the quality of the video conference, you need to increase the bandwidth.


480 x 360 pixels. The optimal resolution for mobile video conferencing.


640 x 480 pixels. The optimal resolution for desktop vc solutions.


1280 x 720 pixels at 30 frames per second. The minimum resolution to quality as high definition.


The capacity of a network to transmit data – video and audio. The greater the bandwidth the better the quality of the picture being transmitted.

CIF (Common Intermediate Format)

These initials stand for common intermediate format, a video format used in vc systems that support both NTSC and PAL signals. CIF is part of the ITU H.261 video conferencing standard.

Cloud Computing/Solutions

Delivering computing services over the internet. This is typically a service provided by hosting providers.


This is the unit that processes the audio and video signals. The term comes from the words coder/decoder which has to do with conversion of digital and analogue signals. It could also relate to the compression/ decompression of the data.


Compression is the reduction of a file size by eliminating redundancies in data. The codec will compress the data (audio and video) that is being sent to the far end, and decompress the data that is being received.

Continuous presence video

This is a common feature in multipoint video conferences where by the screen is split to show all the participating sites at the same time. This is an alternative to voice activated mode – see below.

Data Sharing (Content Sharing)

The ability to show data over a video conference call, such as a powerpoint presentation.

Desktop Video Client

A software application run on a PC, used to communicate over video with telepresence and video conference systems.

Frames per second (FPS)

The frequency with which video frames appear. Broadcast quality video is usually 30 frames per second. Full motion SD videoconferencing typically offers video at 15 frames per second, and now HD at 30 frames.


Mathematical computation designed to thwart unauthorised access.


A video conference device.


A network node set up as a boundary to prevent traffic from crossing over one segment to another.


Often an additional funtion of an MCU, this facilitates two-way communication between dissimilar (H.323 and H.320) video endpoints operating across dissimilar networks, by reformatting data and protocols.


A device that manages video conference call control. It is used to manage call bandwidth, dialling strings and other network settings related to video conferencing.


An arrangement in which another organization runs your infrastructure technology on your behalf. (See Cloud Computing)


The ability of systems from different manufacturers to work together.

ISDN – Integrated Services Digital Network

This is digital telephone lines. Most video conferences are connected using ISDN connection. The cost for ISDN is generally higher than for IP, but the quality of the connection is generally more stable for ISDN than for IP.

IP – Internet Protocol

IP is usually a high quality broadband connection that is used to connect the video conference. The quality of the connection may vary.

Multipoint (MP)

Multipoint is where you are able to connect more than two sites in one video conference. This normally requires a bridge, although some video conference units are also able to connect multiple sites.

Multipoint Conferencing Unit (MCU)

A server on a video network that allows multiple video endpoints to participate in a multipoint conference.


The combination of computer hardware and operating system that applications run on.


Point-to-point is the direct connection of two sites in a video conference. This only works if both sites use the same type of connection (either IP or ISDN).


Session initiated protocol.  SIP is open language, open protocol offering flexibility and the ability to connect on a variety of platforms: phone, email and video.  When the DNS server received a SIP email address it defines its purpose as one of the 3 and directs the call appropriately.

Standards in video conferencing

H320 is a protocol for video conferencing via circuit switched networks such as ISDN H323 is a protocol for video conferencing via IP networks T120 is a set of standards for real time data conferencing H239 is a standard for the simultaneous display of people and data (utilising 2 screens) H264 is a standard for video compression.


Scalable video coding: this is H264+ (Annex G extension of the H.264/MPEG-4 AVC)   It enables encoding of bitstream that contains more than 1 subset of bitstreams.  It is not a purely videoconferencing protocol.

Teleconference / Teleconferencing

A generic term covering live, real time collaboration by video, audio or web.


A high bandwidth, high definition video conference experience often using 3 screens in an immersive setting.


Telepresence Interoperability Protocol. This was developed by Cisco, it supports multi and single screen interoperability across multi-vendor platforms.


This is when a bridge enables different video conference systems to connect when they are not directly compatible. E.g. converting IP to ISDN, (also known as a gateway) or connecting two systems that don’t work directly.

Unified Communications

This term has become popular to describe across the board real time communication (instant messaging, video conferencing, IP telephony etc) and the integration of these technologies with non-real time communications (such as email, SMS, fax). Therefore, as such, it is not a single product, but multiple devices which combine to provide a consistent unified user interface and user experience.

Video Conference (VC)

A video conference is a live meeting (in real time) among several people who are geographically separate from each other and using specifically designed equipment can see and hear each other.

Virtual Meeting Room

A reserved space on a bridge allowing multiple participants to meet.

Voice Activated

This is a feature of multipoint video conferences where the camera view dependes on the audio transmission. The participating sites all see only the site which has last spoken. If someone from a different location speaks the view will then be of that site.


Webcasting is a presentation broadcast over the Internet using streaming media technology. It can be live or stored for on demand.


Short for Web-based seminar, a presentation, lecture, workshop or seminar that is transmitted over the Internet, a key feature being the ability to interact.

Use Eyenetwork to locate video link or video conferencing facilities worldwide

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