Glossary of Terms

A

a/b
Declaration of an analogue exchange connection or an analogue subscriber interface.

AAL
ATM Adaptation Layer. The part of the ATM protocol that breaks up application data packets into ATM cells. There are six ATM adaptation layers:AAL-1: Constant Bit Rate (CBR)AAL-2: Variable Bit Rate (VBR)AAL-3/4: Available Bit Rate (ABR)AAL-5: Unspecified Bit Rate (UBR)AAL-6: MPEG-2.

ANM
Abbreviated number memory. Allows numbers to be stored. These numbers can be retrieved using a short dialling sequence.

ACD
Automatic Call Distribution. The routing of calls fairly within a group, normally used in call centre environments.

ADSL
Asynchronous Digital Subscriber Line. Can reach speeds up to 8 mb. Asymetric Digital Subscriber Line (ADSL) provides high-speed digital connectivity over the existing copper (or analogue) 'local loop' circuit, traditionally used for telephony. It enables Serive Providers to deliver high-speed services such as video, Audio and Internet directly to homes and businesses utilising existing copper lines. The use of ADSL therefore avoidsd the need to install expensive new local loop connections such as fibre optic cable. Further to this, certain ADSL services allow customers to simultaneously use their existing telephones and enjoy higher speed digital connectivity over the same copper line. The lines are described as asymmetric because most of the available banwidth is used to provide fast 'downstreamè speeds from the internet to the end-user whilst the remainder is used for 'upstream' data back to the Service Provider. The service is permanently connected or 'always-on' and is usually charged at a flat rate regardless of time online or data used.

AEC
Acoustic Echo Cancellation. A method for removing acoustic echoes returned from a room that would otherwise cause closed-loop feedback in a full-duplex conferencing system.

AES
Advanced Ebcryption Standard.

AGC
Automatic Gain Control. A method of automatically controlling the gain of an audio path. May be used as a sub component of an audio echo canceller.

Airtime
The amount of time you spend talking, measured in minutes between the time you make and break contact.

Alpha directory
Allows you to store names alphabetically with the associated telephone and fax number.

AMR
Adaptive Multi-Rate. An audio coder/decoder.

Analogue modem
An analogue modem is a small box that sits alongside your computer and connects it to a normal phone line. It converts the digital data generated by your computer - such as files and email messages with attachments - into analogue data that can travel over the public telephone network and the Internet.

Analogue modem card
An analogue modem card fits into a slot inside your computer and connects it to a normal phone line. It converts the digital data generated by your computer - such as files and email messages with attachments - into analogue data that can travel over the public telephone network and the Internet.

Answer only option
Record a message for callers, but don't allow them to leave any for you.

Application Server
This element provides voice, data, or multimedia services from a central location in the IP network.

API
Application Programming Interface. A defined set of calling conventions allowing a software application to access a particular set of services.

Artefact
An unwanted visual aberration in a video image.

ASCII
American Standard Code for Information Interchange. A method of encoding characters into bits. ASCII is the US version of the International Standards Organisations (ISO) character encoding set.

Aspect ratio
The relationship between the width and the height of an image. To avoid distortion this ratio must be kept constant when displaying an image on different screens.

Asynchronous communication
This term describes how your computer uses a modem to connect with other computers. Back in the days of teletypes and dumb terminals, computers sent data synchronously--they operated using a shared timer that marked the transmission of each character. This didn't work very efficiently for large blocks of data over phone lines, however. So modern modems use asynchronous rules: instead of synching up to a time signal to mark a character, transmitting computers use a start bit, a stop bit, and an optional error-checking parity bit to indicate to receiving computers the boundary of each character. (The term is a bit of a misnomer, though, since all modems synch up with one another before they transmit data.)

Asymmetrical Duplex
Asymmetrical Duplex Data flows in both directions at the same time however at different speeds.

ATM
Asynchronous Transfer Mode: A high-speed cell (i.e. packet) based data transmission protocol.

Auto 1471
Automatically records the caller's number unless they withhold it, even if they don't leave a message

Auto Attendant
An automated call answering system that uses prompts to direct users to the correct department or extension. For applications designed to streamline interactions with cutomers.

Auto connect
Automatically connects the line when you lift the handset from its base station.

Auto fax/tel detection
Allows you to receive incoming faxes automatically.

Automatic fallback
Will automatically reduce the speed of transmission to enable both machines to communicate at the same speed.

Automatic time-out
The ability of a telephone device to return itself to the ‘on hook’ setting after a specified period of time should it accidentally be left 'off hook'.

Auto-talk/standby
Automatically connects the line when the handset is lifted from the base.

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