A base station in a wireless LAN. Access points are typically stand-alone devices that plug into an Ethernet hub or server. Like a cellular phone system, users can roam around with their mobile devices and be handed off from one access point to the other.

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Asymmetric Digital Subscriber Line. A DSL, or Digital Subscriber Line, commonly transfers data to and from a subscribers premises by 'piggybacking' onto existing infrastructure, most commonly a standard analogue BT telephone line. Existing mains power supply cabling is sometimes utilised, also satellite or proprietary cabled networks. The data transfer is carried out by means of a high-frequency 'carrier' which does not interrupt the normal working of the existing service used as the vehicle for transmission. Data transfer is divided into two components - transmission and reception. In Asymmetric transfer (ADSL), one (usually transmission) is carried out at a slower rate than the other.

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Advanced Mobile Phone Service. The standard for analog cellular telephones, which uses a frequency-modulated transmission and frequency spacing to separate user transmission. AMPS operates in the 800 MHz band.

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A wireless modem designed for analog cellular phones.

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American National Standards Institute. A membership organization founded in 1918 that coordinates the development of U.S. voluntary national standards in both the private and public sectors. It is the U.S. member body to ISO and IEC. Information technology standards pertain to programming languages, EDI, telecommunications and physical properties of diskettes, cartridges and magnetic tapes.

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Blockwiring
The cabling and termination equipment installed between TJF and Distribution Cases on floors or in risers.

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A new technology designed to be embedded in electronic devices in order to provide wireless and seamless connections over short distances. The idea is to provide an easier to use alternative to the cable-based interfaces currently in use to link computers and computer peripherals. Other devices in which Bluetooth chips could be embedded include mobile telephones, personal digital assistants, headsets and wristwatches.

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A term applied to telecommunications systems capable of simultaneously supporting multiple information formats at relatively high speeds such as voice, high-speed data services and video services on demand. Overall transmission speeds are typically hundreds to thousands of times faster than those of Narrowband systems.

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BSGL
Branch Systems General License

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BSI
British Standards Institute, who are responsible for the drawing up of standards against which equipment is designed for sale in the UK.

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A digital network feature where identity information from the device making a call is interpreted by the device answering the call. This is usually given in that the form of the telephone number of the person who is calling you.

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Cellular Radio is the technology that has made wide scale mobile telephony possible – before cellular radio the problem with the mobile phone as a concept was how to get large numbers of users to share small amounts of radio spectrum. Cellular radio solved this problem by allowing the re-use of the same radio frequencies by assigning them to cells which were far enough apart to prevent noticeable interference.

Frequency Division Multiple FDMA was the basis for first generation cellular radio systems. Second generation cellular radio systems - the current generation - use digital techniques such as TDMA and CDMA to support high bit rate voice and limited data communications. Third generation ( 3G) systems will support voice and high bit rate data allowing mobile multimedia applications (see also Narrowband, Wideband).

Centrex
A service provided by a PTO which uses the local telephone exchange to provide PABX facilities at the customer premises.

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CILE
Call Information Logging Equipment.

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Means of creating telecoms connections by setting up an end-to-end circuit. The circuit remains open for the duration of the communication and a fixed share of network resources is tied up with no one else able to make use of them until the connection is closed. The main advantage of circuit-switching is that it enables performance guarantees to be offered. See also Packet Switching.

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The combination of PABX features allowed for a particular extension or group of extensions.

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It is based on that the ability of the telephone system and computer to exchange information. One example of an application is the ability to present on screen information such as scripts, simultaneously with an incoming call. The scripts are based upon information gathered about the caller prior to the telephone being answered. This is generally achieved by either menu systems or by a identification are of the incoming line which the caller has dialled or his calling line identity.

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DEL
Direct Exchange Line.

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Dialled Number Identification Service (DNIS)

The ability to identify the number to which the call was made. In a call centre, for example the call may come into a specific DDI number. The call is answered by an agent in an ACD group, and the system uses the DNIS to present the agent with a screen containing a script associated with that DDI number.

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Digital Access Signalling System (DASS)

Protocols agreed as a standard for digital signalling between digital PBXs using PCM A-Law and digital public exchanges. Two versions are available:

- single channel connection using 80 Kbps links (see IDA)

- multi-channel (30 channels) connection using 2.048 Mbps links.

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Allows the transfer of PBX facilities between PBXs, even of different makes.

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DDI uses a small group of exchange lines to access a larger number of extensions. The first part of the number selects the line, whilst the last part gives the extension number. This method is very economical on exchange lines.

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DTMF
Dual Tone Multi Frequency See also MF.

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Erlang
A measure of the average activity on a line or group of lines, e.g. exchange lines, extension or operator consoles, over a period (usually an hour) expressed as a number of simultaneous calls. Figures are given in hours and hundredths of an hour, e.g. 4.46 Erlang = 4 hours 28 minutes of traffic.

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The most widely-installed LAN technology. Standardised as IEEE 802.3, an Ethernet LAN uses Carrier Sense Multiple Access with Collision Detection (CSMA/CD) protocol (originally developed to manage radio based data communications - hence the name Ethernet) running over a coaxial cable or twisted pair wires. The most commonly installed Ethernet systems are called 10BASE-T and provide transmission speeds up to 10 Mbps. Fast Ethernet, or 100BASE-T10, provides transmission speeds of up to 100 Mbps and is typically used for LAN backbone systems, supporting workstations with 10BASE-T cards. Gigabit Ethernet provides an even higher level of backbone support at 1 Gbps.

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One of the oldest LAN technologies which has been highly successful and is still popular. It was originally developed by Xerox, Intel and DEC. It was developed to run over coaxial cable although it can now run over twisted pair. It uses CSMA/CD and is similar to the IEEE 802.3 standard in that they share the same cable specification and can communicate with each other. Ethernet can run at up to 10Mbits/s.

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Any of the three versions of 100Mbps Ethernet competing to become an IEEE standard. Grand Junction Networks Inc., HP, and a consortium of vendors (including 3Com Corp., SynOptics Communications Inc., LAN Media, Intel Corp., and Sun Microsystems Inc.) are proposing solutions for the 100Mbps Ethernet standard.

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High speed transmission method, switching packets of data through its network to their destination. Access to the network is via Frame Relay Access Devices (FRADs) which translate the data (eg Ethernet, Token Ring) into frame relay packets. The network sets up a virtual circuit which is a path to the destination. Frame relay is more popular in the US than in Europe, but the main European carriers offer frame relay service. Frame relay can operate at speeds of up to 45 Mbps, since it is a lightweight system without error correction, relying on the integrity of the fibre optic hardware.

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A fully digital telecommunications network access method which works over copper wires. There are two types of ISDN, basic rate and primary rate. Basic rate ISDN provides subscribers with two 64 kbps information channels and a single 16 kbps control channel. Primary rate provides users with thirty 64 kbps information channels and a 64 kbps control channel.

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The device which can interpret and react to voice or tone commands.

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A world-wide network of computer networks in which users at any one computer can, if they have permission, get information from any other computer. The idea was conceived by the Advanced Research Projects Agency (ARPA) of the US government in 1969 and was first known as Arpanet. Since then it has been demilitarised and commercialised and augmented by a series of inventions and innovations, not least of which is the web browser invented by a team led by Tim Berners-Lee in 1991 at CERN, the European Laboratory for Particle Physics. This is the basis for the World Wide Web which has been so successful that it is now often confused in popular conversation with the Internet itself.

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See IP Telephony

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Also known as Internet Telephony or Voice over IP (VoIP). Use of Internet Protocol (IP, see TCP/IP) to carry and route two-way voice communications. IP Telephony can support telephone to telephone links through suitable adapters but also voice communications from telephone to IP terminal (such as a PC with sound card) or from IP terminal to IP terminal. The technique promises drastically reduced costs to carriers and therefore prices to end users – but it still suffers problems with quality.

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ISDN
Integrated Services Digital Network.

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Point of access to the Internet for small business and individual users. The ISP provides its customers with dial-up access to its router which relays traffic to web servers on the Internet.

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Kbps
Kilobits Per Second a measure of the speed of data capable of passing along a line expressed in thousands of bits.

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The frame on which incoming cables from a PTO are terminated.

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A measure of the speed of data capable of passing along a line expressed in millions of bits.

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Abbreviation of modular/demodulator, the modem converts digital computer signals into analogue form for transmission over analogue telephone systems. Modems work in pairs, so at the other end of the channel the signal is returned to digital form. Remember, traditional telephone networks were designed for the human voice, which are analogue, not digital computers.

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A method of dialling using combinations of tones to denote different numbers. Widely used on PABX's, but now also used between PABX's or DELs and electronic public exchanges. Also known as MF4.

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A network is a collection of computers all linked together to share data. Classified according to their geographical extent: LAN (local area network);WAN (wide area network). LANs may be interconnected through WAN connections.

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Non-ministerial government body monitoring the Telecoms industry in the UK.

The method used to move data on the Internet. In a packet switching network, all the data coming from a machine is broken up into chunks. Each chunk includes the addresses of both the origin and the destination. This enables chunks of data from many different sources to intermingle on the same lines and be sorted and directed along different routes. In this way, many people can use the same lines at the same time.

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Now frequently known simply as PBX. A privately operated switching system with exchange lines to a public telecommunications system (e.g. BT or Mercury Networks) and capable of having an operator console connected to it. The term was originally devised to differentiate the PABX from the PMBX. It is now being superseded by the term PBX.

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Lists of all the permissible uses of and attachment to a PABX.

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PSTN
Public Switched Telephone Network.

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PTO
Public Telecommunications Operator (e.g., Cable & Wireless or BT).

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A technique of encoding analogue voice signals into digital form.

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A device which automatically answers a line and delivers a pre-recorded message. Often used to tell a caller that they are in a queue and will be dealt with as soon as possible.

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A feature on PBX phones allowing users to dial programmed numbers by simply pressing one button (or entering a two or three digit code).

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A frame supplied by the PABX supplier providing a connection point for the exchange line and extension ports to the BDF. It acts as a demarcation point between these.

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The next generation Cellular Radio for mobile telephony. Due to come on stream from 2001 onwards, 3G will be the first cellular radio technology designed from the outset to support wideband data communications just as well as it supports voice communications. It will be the basis for a wireless information society where access to information and information services such as electronic commerce is available anytime, anyplace and anywhere to anybody. 3G’s technical and regulatory frameworks have been defined by the ITU with its International Mobile Telecommunications 2000 (IMT-2000) programme, including the establishment of open accessible standards and the identification of international allocated frequency spectrum.

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Collective name for the set of protocols on which the Internet is based. TCP and IP are the best known of this set, but they are by no means the only ones. TCP guarantees that every byte sent from one port arrives at the other in the same order and without duplication or loss. IP assigns local IP addresses to physical network addresses providing a structure which can be recognised by Routers. Other members of the TCP/IP family include the Telnet protocol which allows a remote terminal to log in to another host, the Domain Name System (DNS) which allows users to refer to hosts by name rather than having to know their numeric IP addresses, the File Transfer Protocol (FTP) which defines a mechanism for storing and retrieving files, and HyperText Transfer Protocol (HTTP) which allows information to be transferred from host computers to computers equipped with web browsers.

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Equipment providing no break power supply for the duration of the reserves of its batteries in the event of failure of the primary source of power.

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Looks for all intents and purposes like a private network but is actually just access to a shared network. Careful management and guarantees of quality of service levels ensure that corporate customers get the privacy and facilities they want but at a lower cost.

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See IP Telephony.

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