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  Vehicle Telematics and Mobile Communications Glossary 

I have added a glossary of terms you may come across in the Telematics and Mobile Communications  industry. As there is a convergence of technologies , so there is a convergence of terminology. The terms found in this list range from those commonly used to those of a more obscure nature. Some words have been repeated to reflect a range of sources and explanations. Please let me know if you think a word should be added or a definition changed, by e-mailing. Email enquiries

Select the first letter of the word from the list below to jump to appropriate section of the glossary. If the term you are looking for starts with a digit or symbol, choose the '#' link.

A B C D E F G H I J K L M N O P Q R S T U V W X Y Z # 


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Second generation of mobile telephony systems using digital encoding. 2G networks support voice, low speed data communications, and short messaging services. 


In mobile telephony, 2.5G protocols extend 2G systems to provide additional features such as packet-switched connections (GPRS) and enhanced data rate 


Third generation of mobile systems. Provide high-speed data transmission and supporting multimedia applications such as full-motion video, video-conferencing and Internet access.

The most common modem format. "8N1" describes the way that your computer and the remote are connected. The first digit is normally 7 or 8, the number of data bits. The second character is a letter describing the parity (N for None, M for Mark, S for Space, O for Odd, and E for Even). The last number is the number of stop bits. Data is sent as follows: Start bit (0) 7 or 8 bits of data (parity bit, if used) stop bit (1) (gap bits, if used)

An Ethernet connection that uses UTP (unshielded twisted-pair) wiring.

16550 UART
This is the UART used with most newer computers and high speed modems. There are several variations, but they all include one main feature: they include buffering, so that if data comes in or is sent faster than the computer/modem can accept it, the UART will hold the data (up to 16 bytes) until the computer/modem is ready for it.



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Acoustic Coupler
This is a special cradle in which you place the handset of a phone. This is connected to a modem, and the modem accesses the phone line through this coupler. Modern modems connect directly to the phone line.

Analogue refers to signals that can represent an infinite range of numbers, as opposed to digital which can only be distinct whole numbers. Analogue data often comes from measurements, like a sine wave. The sound a modem makes over the phone is analogue since it can be any of a number of different frequencies. The fixed-line networks usually transfer analogue data and fax. The GSM networks are Digital.

ANSI graphics is a set of cursor control codes which originated on the VT100 smart terminal. Many BBS's use these codes to help improve the sending of characters to communications programs. It uses the escape character, followed by other characters, which allows movement of the cursor on the screen, a change of colour, and more.

A program and database which locates files on the Internet.

From ARPA (Advanced Research Projects Agency) and network. An early experimental network.

American Standard Code of Information Interchange. It uses 7 bits to represent all uppercase and lowercase characters, as well as numbers, punctuation marks, and other characters. ASCII often uses 8 bits in the form of bytes and ignores the first bit.

ASCII transfer
When a text file is sent directly as it is, without any special codes.

Asynchronous Transmission
Transmission method in which the intervals between transmitted characters may be unequal of length. Transmission is controlled by start and stop bits at the beginning and end of each character. This way, if there is line noise, the modem can find out right away where the next byte should start. [See Synchronous communication].

AT command
Any instructions sent to a modem that begin with "AT". See also Hayes AT command set.

AT command set
See Hayes AT command set.

Attention characters
The letters "AT", which get the modem's attention that you are about to send it a command. [See also Hayes AT command set].

Auto Reliable
The ability of a modem to be able to communicate both with modems that do have error-control and/or data compression, and those that do not.

Automatic Crash Notification (ACN) - vehicle onboard system designed to notify a designated call centre in the event of a significant collision, reporting the vehicle location, speed and severity of the crash, deployment of airbag(s) and other diagnostic information from onboard sensors (sometimes referred to as "Mayday systems"). An "Accelerometer" is often used to track the suddenness of the impact and activate notification when preset G-Force is achieved.

Automatic Vehicle Location (AVL) - the automated system and related technology of tracking vehicle locations. AVL systems utilise GPS technology coupled with wireless communication systems to provide a vast array of data to the home station and/or fleet operator.

Airtime – The name often used to describe the amount of calls used on a mobile phone (i.e. 60 minutes of airtime)


Asymmetric Digital Subscriber Line. A digital technology that allows the use of a copper line to send high bandwidths in one direction and a lesser bandwidth in the other. 


Amplitude Modulation – generally used for radio broadcasting on medium wave and short wave

Access Latency

Maximum time that a port will take to either successfully transmit a packet or discard it as measured from the time the packet is presented for transmission.

Access Line

The physical telecommunications circuit connecting an end user location with the serving central office in a local network environment. Also called the local loop or "last mile." See also Local Loop.

Always on

Current dial up services require the user to 'make a call' to the ISP. The connection is only active during the duration of the call. Most xDSL implementations (including ADSL and SDSL) enable the connection to be always on.


The decrease in the magnitude of the power of the signal transmitted over a wire (as a function of distance) measured in decibels. As distance increases, attenuation also increases and hence signal power decreases.


High speed Internet access that works over existing telephone cables. ADSL works by splitting the phone line into two frequency ranges. The frequencies below 4 kHz are reserved for voice, and the range above that is used for data. This is what makes it possible to use the line for phone calls and data network access at the same time. ADSL provides download speeds of up to 8Mbit/s and upload speeds of up to 1Mbits per second. The different upstream and downstream rates define the Asymmetry. Home and small business users would predominantly use this form of DSL.



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The difference between the upper and lower limits of a band. A range of radio, audio, or other frequencies. Since it is so limited, a modem must carefully change data into sounds that "fit" within this range. Similar to frequency spectrum. Bandwidth of a voice channel is 3000Hz-300Hz which equals 2700 Hz. Telephone lines have a bandwidth from 300 hertz to 3400 hertz.

Beginners All-purpose Symbolic Instruction Code. It is a programming language. It is called symbolic because it allows programmers to use symbols to represent numbers and information. In algebra, these symbols are called variables.

Balanced/unbalanced. A device which connects a balanced (two-wire) line, such as a phone line, to an unbalanced (coaxial) line, like cable. The two-wire line is called balanced because the currents in each wire are equal and in opposite directions.

A term referring to the speed at which modems communicate. Technically, it is the number of changes in an electronic signal per second. Since the number of changes used to be the same as the number of bits sent or received per second, bps and baud are often used interchangeably. However, there is a difference, which is very often confused. For example, many 1200 bps modems were advertised as 1200 baud, even though they operate at 600 baud. They send out 2 bits 600 times a second, which means that it is 600 baud. However, since it is so often misunderstood, you can assume that when you see "baud" it means bits per second, unless it is stated otherwise. The term comes from the scientist J. M. E. Baudot. [See also bps].

Binary File Transfer

Billion Rand
What it costs to start a cellular network

A Binary digit. It is a number in base 2 (binary), which means that it can only be a 0 or a 1. It is used in the expression `bits per second'. [See also byte].

Bits Per Second. The transmission speed of most modems is measured in baud or bps. Bps is literally the number of bits sent by the modem every second. [See also baud].

Block size
When used with either error control or data compression protocols, refers to the number of characters to be sent at one time. If error control is used, the codes are sent immediately following this block. Typical block sizes are 64, 128, 192, or 256 characters. Small block sizes are better when the line quality is bad (such as for long distance calls), while large block sizes are better during good connections (such as for local calls).

A group of 8 bits. It usually represents one character.

Bluetooth – A wire free connection that enables devices to exchange information.

BARB The pan-industry body which measures television viewing 

Bluetooth  Wireless standard for short-range radio communications between a variety of devices such as PCs, headsets, printers, mobile phones, and PDA's. 

Broadband  A service or connection generally defined as being "always on" which allows simultaneous voice and data calls and provides a downstream data bandwidth greater than a standard dial-up connection. 


Broadcasting Standards Commission, one of the regulators replaced by Ofcom in 2003 


British Telecommunications plc.


The amount of data that can be sent through a given communications circuit per second

Bandwidth on demand

Designed for organisations that require different amounts of bandwidth at different times of the day.


Broadband is any technology that provides users with a bandwidth of more than 100kbit/s. That technology can use either copper twisted pairs, cable from television service providers, satellites or wireless technologies.



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Consultative Committee International on Telephones and Telegraphy. Used to set standards for modems. Replaced by the ITU.

Card Services
DOS and Windows 3.1x users must have Card Services enabled to use their computer's PCMCIA slot(s). Card Services simply allows DOS/Windows 3.1 to see and set up the computer's PCMCIA slot. They will automatically allocate a Communications Port (COM 1 to 5) when the Option modem is plugged in. The Option modem can then be accessed by communications programs via the Windows 95-assigned COM port. Windows 95 users DO NOT need to install Card Service as it is built into Windows 95. Notebook users using DOS/Windows 3.1 usually have the Card Services software bundled with their purchase. Option modems come packaged with a PC Card Installation disk that has an install program for these Card Services.

Carrier Detect
The information as to whether or not the modem senses a carrier, like a fixed-line dialling tone or a data/fax services enabled on a GSM subscription.

Card Information Services. A PCMCIA setup protocol.

Carrier Detect Threshold
A way of measuring how well a modem can detect valid data over noisy phone lines. It is measured in negative dBm's (decibel-milliwatts). The bigger the number (the more negative) the better. For example,45 dBm is better than40 dBm.  

Caller Line ID Presentation. A code that is sent over the phone lines in some areas when a person makes a phone call. This code includes the phone number of the person making the call. Some modems are able to understand this signal, and let you know who is calling you before you answer the phone.

Caller Line ID Restriction. The ability to block someone who you're calling from seeing your number.  

Cellular Digital Packet Radio

The receiver/transmitter a GSM phone connects to; the equivalent of the base station of a cordless phone. A cell can support a number of simultaneous calls.

A number that represents a larger group of numbers in order to check for errors in data transmission. It is commonly used when downloading a program, as well as in error control protocols. The checksum is the result of a mathematical equation, such as adding all the numbers in a block together (although it is usually more complex than that). 

Chip Set
A group of important IC chips on a modem (or other computer peripheral) that are all made by the same manufacturer. While there are many companies that make modems, there are only a few that make the chips for them. Because the chip manufacturer is making the chips for many companies, they produce more chips, and the price of the chips is lower than if each company produced their own. This decreases the price of the modems on the market.

Code Division Multiple Access. A digital cellular technique invented by Qualcomm.

Complementary Metal Oxide Semiconductor. A chip which uses small amounts of electricity. It is used typically on battery-powered computers and to save configuration information on other computers when they are turned off.

Communications program
A program that controls a modem, and has features that allow the user to do such things as upload, download, etc. It is similar to a terminal program but more sophisticated. An example is Trumpet WinSock for connecting to the Internet, and Windows HyperTerminal.

When one object can work just like another. Although the term is usually used with computers, it is often used with modems. Many modems are compatible with other popular modems.

To make data take up less space. Archiving programs do this, which means that files will take less time to transfer with modems. Many modems now have the ability to automatically compress the information they send and receive. [See also archive, data compression].

Compressor/DECompressor, the chip inside every digital GSM cellphone that allows the cellphone to transmit voice data at high efficiency and speed across the GSM cellular network. The CODEC will trip redundant voice data like when neither party is talking allowing more efficient use of scarce bandwidth.


Conference of European Post and Telecommunications, the European telecommunications authority.

From hacker and safe cracker. A hacker who breaks into computers


Clear To Send. This is when the modem lets the other computer know that it can send information to the other computer. [See also Flow Control, Return To Send].



The method of flow control that uses the CTS and RTS signals. It is built into the hardware, not software. [See also CTS, RTS, flow control].

CDMA – Stands for Code Division Multiple Access, which is a mobile technology, operated in several countries including the USA and South Korea.


Carrier Pre-selection. The facility offered to customers which allows them to opt for certain defined classes of call to be carried by an operator selected in advance (and having a contract with the customer) without having to dial a routing prefix, use a dialler box, or follow any other different procedure to invoke such routing  


Commercial Radio Companies Association 


Contract Rights Renewal. The mechanism by which potential abuse of ITV’s dominant position in the advertising market is prevented, imposed as a condition of Carlton and Granada’s merger. The mechanism prevents ITV1 increasing its rates unless its share of commercial impacts also increases

Contention Ratio

This describes the maximum number of users sharing the bandwidth on the connection between your local exchange and the Internet Service Provider. A customer with a contention ratio of 20:1 may have to share this bandwidth with up to 20 other users at peak loading. However this is unlikely as not all users will be using the service at the same time.


Customer Premise Equipment. This refers to any equipment located at the customer's premises. DSL modems, bridges and routers are examples of CPE




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Data Access Arrangement. A device used to connect modems to the switched telephone network.

Data over GSM
Send digital data over the digital GSM networks.


Data Circuit Terminating Equipment. Sets up and maintains a data connection link over a communications medium. For example, a modem.


Data Compression
Some modems have the capability to 'squash' data so that it takes up less space. When another modem (that also has this capability) receives the data, it 'unsquashes' the data to its original form. By using data compression, a modem can send information faster. It's a lot like shorthand--all the information is still there, but it takes less space and is quicker. [See also MNP-5, V.42bis].


Data Transmission rate
The speed at which data travels. For example, data may be sent at 115,200bps. Same as transmission rate, transmission speed, data rate. [See also bps].

Decibel refers to one milliwatt. This is used to measure certain levels, such as transmit level.

Data Services Adapter, an alternative interface to PCMCIA for connecting to a fax or data terminal. The Siemens S1 uses a DSA

A system using discrete numbers to represent data. In computer systems, these are the numbers 0 and 1 (for binary). [See also Analogue].

Data Set Ready. This indicates that the modem is on, and ready to accept input from the computer (either commands or data to be sent over the phone line)

Data Terminal Equipment. This is computer equipment which is not directly responsible for communicating, for example, the computer itself and printers. [See also DCE].

Dual Tone Multi-Frequency. This is used in tone dialling. It is a method where 2 distinct tones are sent for each digit dialled.

Data Terminal Ready. The DTR signal is sent from the computer to the modem, to let the modem know that the computer is ready to communicate.

Data Packet - Information about a vehicle or group of vehicles, or other non-voice data, transmitted via communication conduits (cellular, Internet, etc.) to the fleet management system computer.

Differential GPS - using data from at least four (4) GPS signals, this method of GPS corrects for a designed random error to achieve a more precise location, usually within 2 meters. This system utilizes a fourth location signal from land based signal towers maintained by the US Coast Guard to enhance the accuracy of GPS for navigation on the waterways.

 Data Cable – Sometimes referred to as an I/O cable, a data cable is used to connect a data enabled satellite phone to a laptop. As with other forms of mobile data, this enables the user to send and receive data, e-mails and also to browse the Internet. However as the information is being received via a satellite phone, the data is accessible from the remotest regions of the planet.


Digital Audio Broadcasting (Digital Radio) 


Department for Culture, Media and Sport 


Digital Radio Development Bureau 


Digital Subscriber Line. A family of technologies generally referred to as DSL, or xDSL, capable of transforming ordinary phone lines (also known as 'twisted copper pairs') into high-speed digital lines, capable of supporting advanced services such as fast Internet access and video-on-demand. ADSL, HDSL (High data rate Digital Subscriber Line) and VDSL (Very high data rate Digital Subscriber Line) are all variants of xDSL)  


Department for Trade and Industry 


Digital Terrestrial Television, currently most commonly delivered through the Freeview service

Dial up

A term used to refer to slower Internet Access using a phone modem. Usually, the user dials a telephone number and using the computer in order to connect to the Internet. The maximum bandwidth of a dial up connection is 56kbit/s.


(Domain Name system) Name resolution software that lets users locate computers on a UNIX network or the internet (TCP/IP network) by domain name. The DNS server maintains a database of domain names (host names) and their corresponding IP addresses.


Data flowing from the Internet to your computer (surfing the net, getting email, downloading a file)


DSL (Digital Subscriber Line) provides high-speed Internet Access using regular telephone lines. It has the ability to move data at speeds up to 8Mb/s or eight million bits per second, or 140 times quicker than the fastest analogue modems available today.


A DSLAM (Digital Subscriber Line access Multiplexer) is a device located in the central office switch that enables it for xDSL capabilities.

Dynamic IP Address

An IP address that is automatically assigned to a client station in a TCP/IP network, typically by a DHCP server. Network devices that serve multiple users, such as servers and printers, are usually assigned static IP addresses. (See static IP address)



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EDI Electronic Data Interchange. Commonly transferred by Internet or X.400 networks

EEPROM Electrically Erasable Programmable Read-Only Memory

EFF Electronic Frontier Foundation. An organization promoting civil rights in cyberspace. It is leading the fight against the US government's Clipper Chip.

Error Correction The ability of a modem to notice errors in transmission, and to resend incorrect data. [See also MNP 1-4, LAPM, V.42].

ECFP European Conference on Computers, Freedom, and Privacy.

E-mail Electronic mail. Messages that are sent to individual people. You choose who to send the message to and only that person receives the message.

ESPRIT European Strategic Program for Research in Information Technologies.

Error When there is line noise and one or more characters are changed. This is especially noticeable when downloading or uploading a program. In this case the error must be detected, and the data must be re-sent.


Earnings Before Interest, Depreciation and Amortisation



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FAQ Frequently Asked Questions.

Firewall Computer security that attempts to keep crackers out.

Flame To write emotional remarks on electronic mail.

Flow control A method of controlling when information is sent. One method is Xon/Xoff, where a BBS will send information until your computer sends an Xoff (CTRL-S). It will resume sending information when you send an Xon. [See also Xon/Xoff,CTS/RTS].

Full Duplex A channel providing simultaneous transmission in both directions.

FCC Federal Communications Commission – the US regulator of television, radio and telecommunications 

FM  Frequency Modulation – generally used for radio broadcasting on VHF (Very High Frequency)

Firewall  A firewall is designed to keep a network safe from intruders. It can be a single router that filters out unwanted packets or may comprise a combination of routers and servers each performing some type of firewall processing.



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The method of modulation used by GSM is Gaussian Minimum Shift Keying (GMSK), with a BT value of 0.3 at a gross data rate of 270 kb/s.

The standard controlling fax communication.

GSM originally stood for Groupe Speciale Mobile but has been anglicised to Global system for Mobile Communications, an international digital cellular standard. South Africa was one of the first to implement Phase 2 of GSM.

Galileo - essentially the European version of GPS, this system is currently under development. It will ultimately consist of 21 to 28 satellites in a mid-Earth orbit (MEO) and between 3 and 8 satellites in geosynchronous (GEO) orbit, which may use signals from GPS.

General Packet Radio system (GPRS) - packet switching technology where information is transmitted in short bursts of data over an IP-based network allows continuous connection to data networks in support of many kinds of applications, including messaging and rapid data transfer.

Geocoding - Using latitude and longitude data from the GPS receiver to determine the map location and (with software) find the exact street address or block address.

GeoFence - A GeoFence is a geographic boundary that can be defined for the purpose of monitoring an asset or vehicle.  It could be used in conjunction with a vehicle security tracking system that  records all entry and exit of assigned vehicles from GeoFence boundaries and can alert the system users when these "events" occur.

GeoInformation - is a shorter name of Geographic Information. Geographic information is created by manipulating geographic (or spatial) data (Geodata) in a computerised system. systems can include computers and networks, standards and protocols for data use and exchange between users within a range of different applications. Typical applications are land registration, hydrology, cadaster, land evaluation, planning or environmental observation.

Geodata - comes in many different forms, such as maps or images taken from the air or from space, i.e., remote sensing data. Geodata may be stored in a database, which may possibly have special extensions for storing, handling, and manipulating spatial data. Geoinformation is the useful output, produced by analysing data with a kind of computer program called a "geographic information system", or GIS. The environment in which a GIS operates (machines, people, networks) is called a "spatial information system", and is designed and created to respond to the strategic spatial information needs of people or organisations.

Geographic Information systems (GIS) - a combination of the geospatial data systems and software designed to support transportation routing and logistics, generally for a municipality or regional area.

Global Orbiting Navigation Satellite system (GLONASS) - a Russian space-based navigation system comparable to the American GPS system, GLONASS is comprised of 21 satellites in 3 orbital planes, with 3 on-orbit spares.

Global Positioning system (GPS) - A technology that uses signals and data from multiple satellites to determine a location anywhere on Earth.

Global system for Mobile Communications (GSM) - originally short for 'Groupe Spécial Mobile' GSM is the digital wireless communication standard for Europe, as well as South Africa, Australia, and many Middle and Far East countries. GSM has recently been introduced in the United States and is rapidly expanding throughout North America

GPRS - This stands for General Packet Radio Services and is one of the latest advancements in mobile data. It is a GSM Packet Based bearer for the delivery of data services. With GPRS you only pay for the amount of information you download rather than the duration of the connection.

GPS – This stands for Global Positioning system. It is a radio positioning system which provides location information via satellite, enabling the accurate pinpointing of GPS equipped vehicles and moving objects.

GSM – Stands for Global system for Mobile communications and is an international standard which allows you to use one phone and one number worldwide. GSM is a digital technology and therefore the call quality is of a very high standard, calls are always clear, and the network is very secure. GSM enables clients to cross international boundaries with just one phone number.


Gross Domestic Product 


General Packet Radio Service, a packet data service provided over so-called 2.5G mobile networks 


Global Standard for Mobile Telephony



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Half Duplex
A channel which signals in both directions, but not simultaneously.

What occurs when a cell phone used in a car moves out of the range of one cell and needs to connect to the next available cell. The preceding cell then hands over the connection to the stronger cell.

Hayes AT command set
This is the set of commands used to operate Hayes modems and Hayes compatible modems. Almost all of the commands start with AT.

Hayes compatible
Any modem which operates in the same way as the modems developed by Hayes.

A unit of frequency, which equals cycles per second.


High Speed Datalink Packet Access

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The International Standards Organisation, the body responsible for setting world technical standards. It is based in Geneva, Switzerland.


International Telecommunications Union, based in Geneva, Switzerland.


InterWorking Unit. This is the network "modem" where all the digital to analogue (and visa versa) conversions take place within the digital GSM networks


Intelligent Transportation systems (ITS) - A general term for many technology systems used in highway, rail and other transit to improve mobility, reduce accidents, and improve transportation overall, i.e. electronic toll collection systems, synchronized traffic signals. 

iDEN – Stands for Integrated Digital Enhanced Network.


Independent Broadcasting Authority 


Independent Local Radio – the former name for local commercial radio in the UK 

Interconnection  The linking of one Public Electronic Communications Network to another for the purpose of enabling the persons using one of them to be able (a) to communicate with users of the other one; (b) to make use of services provided by means of the other one (whether by the provider of that network or by another person). 

Internet  A global network of networks, using a common set of standards (e.g. the Internet Protocol), accessed by users with a computer via a service provider. 

IP Internet Protocol. The packet data protocol used for routing and carriage of messages across the Internet and similar networks.

ISDN Integrated Services Digital Networks A standard developed to cover a range of voice, data, and image services intended to provide end-to-end, simultaneous handling of voice and data on a single link.  

ISP Internet Service Provider. A company that provides access to the Internet.  

ITC Independent Television Commission, one of the regulators replaced by Ofcom in 2003

IP address (Internet Protocol address) The address of a computer attached to a TCP/IP network. Every client and server station must have a unique IP address. Client workstations have either a permanent address or one that is dynamically set assigned to them each dial up session (see Static & Dynamic IP address for more detail) IP addresses are written as four sets of numbers separated by periods; for example,



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Kbps – This stands for kilobytes per second and is used to indicate data speed.



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Famous for the Lotus 1-2-3 spreadsheet of the 1980's, and more recently for it's Notes Groupware system. Bought by IBM in 1995.


Local area network. A network allowing the interconnection and intercommunication of a group of computers on a single site, primarily for the sharing of resources and exchange of information (e.g. email). 

Leased Line

A transmission facility which is leased by an end user from a public carrier, and which is dedicated to that user's traffic. 


Local Loop Unbundling. A process by which BT's exchange lines are physically disconnected from BT's network and connected to other operators' networks. This enables operators other than BT to use the BT local loop to provide services to customers. 

Local Loop

The access network connection between the customer's premises and the local PSTN exchange, usually a loop comprised of two copper wire

Lone Worker Device

Soon to be a government requirement in some countries (i.e. Canada by 2007), One example of a lone worker device is an RFID-based handheld that will be required for workers that spend any time alone during the day.  This device requires the lone worker to physically acknowledge ‘pings’ (vibrations or beeps) by pressing a button on the handheld every predefined interval.  If that worker fails to respond to 2 or more pings, it communicates via RFID back to the telematics unit which sends a notification of the lone worker’s GPS co-ordinates.  Emergency buttons are also available on lone worker devices.

Loop Qualification Check

A test that the telephone company can perform to see how far a customer is from the Central Office Switch


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The world's largest developer and publisher of software based in Redmond, Seattle, USA. Headed by William (Bill) Gates, the richest (non-royal) person on this planet.

A process whereby a signal is transformed from its original form into a signal that is more suitable for transmission over the medium between transmitter and receiver.

A GUI (Graphical User Interface) for accessing the hypertext WWW (World Wide Web) on the Internet.

Microcom Networking Protocol. Error control and data compression techniques, created by Microcom, that many newer modems use. They are built into the modem, unlike software error correction in file transfer protocols. There are different MNP levels. Levels 1-4 are error control protocols, and level 5 is a data compression protocol that can compress data to about 50% of its original size. A modem with MNP-5 also has MNP-4. MNP 1-4 is also included in the ITU V.42 error correction system.

MNP normal mode
This is the more common mode used with modems that have MNP capability, where the speed from the computer to the modem can be higher than the connection between the modem and the remote modem. This mode uses buffering to prevent lost data.

Memorandum of Understanding, the GSM body that overseas GSM standards and implementation around the world. It comprises operators and some manufacturers.

A Modulator DEModulator computer peripheral which allows a computer to communicate over telephone lines. This is the heart of computer telecommunications. The main factor that differentiates modems is their speed, measured in bps. Analogue modems talk to one another by converting digital info from the computer into tones called PSK’s. An ordinary analogue modem cannot be physically connected to a GSM phone because networks will not carry PSK tones.

MPDS – Mobile Packet Data Service (MPDS) is a feature available on the Inmarsat M4 Satellite Terminal. It provides "always on" IP connectivity. Users of the service only pay for data packets transmitted and received, rather than the time connected.


Multimedia Messaging Service. The next generation of mobile messaging services, adding photos, pictures and audio to text messages.  


A device that sends multiple signals or streams of information on a carrier at the same time in the form of a single, complex signal. The separate signals are then recovered at the receiving end.




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National Centre for Automated Information Research.

Network Operators
The folks who install and maintain GSM cellular networks.

Non-Transparent Cellular Data
Non Transparent phones use a special error correction technique called RLP. Transparent phones data not incorporate the RLP error correction technique and their data MIGHT be corrupted.

NAVSTAR - The Navstar Global Positioning system (GPS) is a space-based constellation of orbiting satellites providing navigation data to military and civilian users all over the world. This system is maintained by the U.S. Military and provides the foundation for almost all commercial GPS systems in use in the United States.

Nextel – The largest all digital network operator in the USA. Nextel has coverage across the USA and Canada, as well as roaming in many key cities in South America. Nextel operates on the iDEN network.


A service or connection providing data speeds up to 128kbps, such as via an analogue telephone line, or via ISD


Network Address Translation. This allows an organisation to present itself to the Internet with far fewer IP addresses than there are nodes on its internal network. The NAT technology, which is typically implemented in a router, converts the private IP addresses (such as in the range) of the node on the internal private network to one IP address or of several IP addresses for the public Internet. It changes the packet headers to the new address and keeps track of each session, so that when the packets come back from the Internet, it performs the reverse conversion to the IP address of the client machine. NAT also serves as a firewall by keeping internal addresses hidden from the outside world.


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Organisation for Economic Cooperation and Development. 


Office of Communications. The regulator for the communications industries, created by the Communications Act 


Office of Telecommunications, whose functions transferred to Ofcom on 29th December 2003. 


Office for National Statistics



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Private Branch Exchange. This is the telephone system that many offices have, allowing extensions for each telephone, and a connection to the main telephone system.

Parity Bit
Most modems have the capability to send an extra bit for every byte sent, which is used to help sense errors. This is called the parity bit. It can be set to no parity, mark parity, space parity, odd parity or even parity. Most BBS's do not use a parity bit. [See also 8-N-1].


PC Cards
Previously known as PCMCIA cards, these are credit card devices used in notebooks and desktop readers for inter alia, data/fax, storage, GPS purposes.

A credit card sized card that generally plugs into a notebook computer. It conforms to the Personal Computer Memory Card International Association spec. Now known as PC Cards.

Phase Shift Keying. In this method of modulation/demodulation, there are two frequencies used (usually 1200 hertz and 2400 hertz). There are 4 different phase angles (0, 90, 180, and 270 degrees), representing dibits 00, 01, 10, and 11. This is usually used for 1200bps transmission. Note that the baud rate using PSK is really 1/2 of the bps rate, since 2 bits are sent at a time instead of one. [See also modulation].

Public Switched Telephone Network. This is the regular phone lines that just about everybody uses.

A person who spends a lot of time trying to find out as much as possible about the telephone company [like South Africa's TELKOM], and how it works. They often try to find out ways to make long distance calls for free. Some steal calls from telephone credit card users, some steal calls from the phone company directly, and others don't make "free" long distance calls. They are sometimes confused with hackers.


The program which will create an archive with the extension "ZIP". It is one of the most popular archive programs.


Pulse dialling
A method that some phones use to dial numbers. It involves a series of "clicks." Most modems support this type of dialling, which is the only type available in some remote areas. The other method of dialling is tone dialling.

Ping - A vehicle status update request, available only with fleet management systems offering active/real-time vehicle location capability.

PC Card – Sometimes referred to as PCMCIA cards, PC cards are used to connect a mobile phone to a laptop, enabling the user to expand their communications capabilities whilst on the move. Once connected they can send and receive data formats, e-mails and also browse the Internet.


PCS – Personal Communication Services (PCS 1900 or GSM 1900). The North American GSM service operating on 1900 MHz as opposed to the European standard of 900 MHz. Due to the differing frequencies, customers will need to rent a Cellhire handset to roam in North America.


PDC – Personal Digital Communications. This is the mobile technology operated in Japan and is not compatible with any other mobile services, including GSM.


Pre-paid – The term that describes payment in advance for airtime. 


Producers Alliance for Cinema and Television, the UK trade association for independent film, television, animation and interactive media companies 




Personal Digital Assistant  


Partial Private Circuit 


Public Switched Telephony Network.  


Personal Video Recorder




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RLP (Radio Link Protocol)
Non-transparent data uses a special ensure robust GSM-specific error correction technique called RLP for transmission. Both MTN and Vodacom GSM networks support both techniques.



Regular Pulse Excitation - Long Term Prediction, the speech coding used by GSM

Research and Development in Advanced Communication in Europe.


A modem can be reset. This will change any options (such as parity and speed) to the values that they have when the modem is first used. This can be useful if you change some values for the modem and aren't sure what they do, and then you find that the modem won't work. Resetting the modem will fix everything for you. With Option modems, this is the ATZcommand.


This is a normal phone jack. The older South African plugs have a 3-prong connector. All Option modems sold in South Africa have this RJ-11-to-3-prong adapters.

Request To Send. This is when the computer tells the modem that it wants to send information to the other computer. It is only used in half duplex mode. [See also flow control, CTS].

Random Error Code - This is a designed error for commercial GPS systems and was set up in 1982 when the U.S. Military was instructed by      Congress to make GPS available for commercial use. The error is intended to prevent the Navistar system from being used accurately against the U.S. Military. In 2000 the error was reduced from 100 meters to approximately 9 meters. Differential GPS, maintained by the U.S. Coast Guard, corrects this intentionally designed random error.

Roam / Roaming – The ability to use networks overseas and cross geographical boundaries whilst using a single number and a single phone.


Radio Advertising Bureau 


Radio Joint Audience Research – the pan-industry body which measures radio listening

Reach (Radio)

The number of adults 15+ who listen to at least five minutes of radio in a 15 minute period during a week 

Reach (TV)

The number of adults 4+ who watch at least fifteen minutes of a specified TV channel in a specific week (or in an average week over a longer period) 


Restricted Service Licence



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Serial Transmission
A method of transmitting data in which bits are sent sequentially.

Special Interest Group. The GSM MoU has many SIGS.

Subscriber Identity Module. This is a Smart Card installed in every GSM handset. Within the GSM application the three primary roles of the SIM are access control to   the network (authentication & ciphering), service personalisation (SMS, advice of charge, etc.), network branding and advertising (graphics printed on SIM card). The new generation of Phase 2+ SIMs will enable services such as virtual cash, mobile banking, ticket reservations etc.

Short Message Service will display a pager-like 160 character message in the LCD panel on the phone. Your phone must support SMS.

When data is sent continuously, without waiting to make sure there are no errors. Transparent mode on GSM is an example of a streaming method faster than non-transparent mode, but unreliable.

Selective Availability - prior to May 2000, the US military intentionally degraded the accuracy of GPS signal data for civil and commercial purposes as a protective measure. The Department of Defence retains the right to restrict signal accuracy in the interest of US national defence.

Satellite Phones – Where GSM is not available, or in areas where coverage may be limited, Cellhire can provide you with a satellite phone which is simple to use and operates on a truly global scale.


SIM card – Subscriber Identity Module card. This removable card is the chip inside a GSM phone with information such as the user’s phone number, phone book as well as other information related to the subscriber.


SIMSmart® - SIMSmart® enables you to benefit from using cost effective local airtime, wherever you travel in the GSM world – all with your existing handset.


Symmetric Digital Subscriber Line. Unlike ADSL, it offers the same fast data rate speeds in both directions. 

Service provider

A provider of electronic communication services to third parties whether over its own network or otherwise. 

Share (Radio)

Amount of listening hours to a particular radio station as a percentage of all radio listening within that station’s Total Survey Area 

Share (TV)

Proportion of total TV viewing to a particular channel over a specified time period 


Small or Medium sized Enterprise. 


Short Messaging Service.


SDSL (Symmetric DSL) is a single twisted pair line, carrying 2.3Mbit/s each direction on a duplex line. The term symmetric is used in this context, as the data rate is the same in both directions.

Static IP Address

A permanent IP address that is assigned to a node in a TCP/IP network. Servers and routers are usually assigned static IP addresses, while client stations are often assigned dynamic IP addresses from a DHCP server each time they come online. (See Dynamic IP address)


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Trunk 1. A heavy duty telephone line.

Trunk 3. A telephone trunk line.

TDMA: Time Division Multiple Access, the magical technique used by the digital GSMnetwork to squeeze more calls onto one channel by dividing a calling channel into a few "discontinuous" pieces.

This word has no precise definition, but is frequently used. Its definition ranges from "any form of communication over a distance" to "any communication by electric means" to "two computers 'talking' to each other via modems." Methods of communications that probably are considered telecommunications: telephones, cellphones, TV's and fax machines. The word is used both in singular and plural.

The idea of company employees working from home, rather than their office. At home, they can communicate with the office (and other entities) by modem or voice calls.

Telkom (South Africa)
Telkom is the parastatal fixed-line network operator in South Africa. Option modems are approved for use on the telkom network and 25 other networks around the world.

A program which lets you access other computer systems through Internet.

Terminal Emulation
When a communications program can simulate the operations of a smart terminal.

Tone Dialling
This is a method that a phone or modem can use to dial a phone number. It uses one audible tone per digit to be dialled.

Transmit Level
The "loudness" level of the sound leaving a modem to go over the phone lines. It is measured indBm's. It should be different at different frequencies, since certain frequencies have more loss over the phone line than others.


Transparent Data Transmission
A method of transmission in which the transmission medium will not recognise control characters or initiate any control function. Transparent-based phones do not utilise any error correction. Thus the data sent and received MIGHT be corrupted unless a greater than two-bar cellphone signal is used (South African conditions). Non-transparent data uses a special ensure robust GSM-specific error correction technique called RLP for transmission. Both MTN and Vodacom GSM networks support both techniques.

Telematics - a general term referring to emerging technologies in automotive communications, combining wireless voice and data capability for management information and safety applications.

Telematics Service Provider - An organisation that provides a range of telematics services, including vehicle tracking, trailer tracking, mobile data and RFID


or 'Telecoms'  Conveyance over distance of speech, music and other sounds, visual images or signals by electric, magnetic or electromagnetic means.



Total Survey Area – the coverage area within which a radio station’s audience is measured by RAJAR



Television Without Frontiers directive, adopted by the European Council in 1989 and amended in 1997


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Universal Asynchronous Receiver/Transmitter. This is a device in a computer or modem that will change serial data (the way data comes in over the phone line) to parallel, and vice versa. [See also serial, parallel, 16550 UART, 8250 UART, 16450, 16550 UART].


Universal Mobile Telecommunications system


Data flowing from your computer to the Internet (sending emails, uploading a file)


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The ITU standard for fax transmission at 14,400bps.

The international standard, created by ITU, that controls transmission at 300bps.

The international standard for transmission at 1200bps, created by ITU.

The international standard, created by ITU, that controls data transmission at 2400bps.

The ITU protocol for transmission of 1200bps one way, 75bps the other way.

This, combined with V.28 is the ITU standard equivalent to EIA's RS-232C standard. V.24/V.28 has 25 pins, just like the original RS-232C standard.

Part of V.24.

The ITU standard for 9600bps half-duplex communications.

The international standard controlling transmission at 9600bps. It was created by ITU. It has provisions for fallback, if the line is too noisy.

The international standard for 14,400 bps modems, ratified by the ITU.

The international standard for 28,800 bps modems, ratified by the ITU.

A standard error control system created by ITU that is in use on many 9600bps modems and some 2400bps modems. It includes LAPM, as well as MNP 2-4.

V.42 compatible
This is a modem that follows all the V.42 specifications, except for LAPM error control (instead it uses MNP).

V.42 compliant
This is a modem which follows all the V.42 specifications, and uses LAPM error control if possible. Otherwise, it will go to MNP error control.

A ITU standard for data compression. It can compress data with about a 3:1 compression ratio, although it can compress up to 4:1 given the right conditions. Any modem with V.42bis also has V.42 error control. [See also Data Compression].


Vehicle Area Network, where the telematics device acts as a Wi-Fi access point for laptops, PDA’s, etc. around the vehicle.

VoiceMail The term used for mobile and cellular voice message services. The phone alerts you to indicate receipt of a message


Voice over Broadband. A technology that allows users to send calls using Internet Protocol, using broadband services 


Voice over Internet Protocol. A technology that allows users to send calls using Internet Protocol, using either the public Internet or private IP networks.

VOD (Video On Demand)

The ability to activate a stored or live motion picture stream; in xDSL the application that allows subscribers to view movies or other video programming on request, similar to cable television's Pay-Per-View. See Pay-Per-View.


VDSL (Very high bandwidth DSL) is in the early development phase but promises much higher data rates over relatively short distances (between 51 and 55 Mbit/s over lines up to 1,000 feet or 300 metres in length)


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World Wide Web

World Wide Web. A hypertext system set up on the Internet.

A DOS program to perform UUCICO.

A Windows subroutine library that provides access to the Internet TCP/IP.

The actual file containing Winsock.



Wide area network. A network allowing the interconnection and intercommunication of a group of computers over a long distance. 


Wireless Application Protocol. 

Wireless LAN or WiFi

(Wireless Fidelity)  Short range wireless technologies using any type of 802.11 standard such as 802.11b or 802.11a. These technologies allow an over-the-air connection between a wireless client and a base station, or between two wireless clients.  

Wireless Hot Spot

When a service vehicle is parked within 200m of their local garage, workstation, etc.. it makes sense to provide them an 802.11a/b/g “hot spot” that their telematics device connects to, giving them fast, free, and secure access to their local network removing the need to use the expensive 1X network.  More and more companies are finding that the majority of the technician’s internet time is spent near their home location.  If the telematics unit has both 1X and Wi-Fi, wireless hot spots reduce unnecessary airtime charges.


Wholesale Line Rental. A regulatory instrument requiring the operator of local access lines to make this service available to competing providers at a wholesale price.


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This is a packet-switching protocol developed by ITU. It is used to carry large amounts of data at fast speeds over leased phone lines.

This is ITU's 1984 update of X.25, also known as X.25 dialup.

This is the ITU standard protocol for a global system for the exchange of electronic mail.

The ITU standard for a directory of the users of the X.400 system.

A file transfer protocol developed by Ward Christensen around 1977. It is fairly slow by today's standards, but was the first widespread file transfer protocol. It uses blocks of 128 bytes, and after each block is sent, it sends a 1 byte checksum to check for errors. If an error is encountered, the block will be re-sent. Almost every communications program offers this protocol.

The same as Xmodem, but it has a 16-bit CRC instead of the checksum, which makes it more reliable (it catches more errors).

This is similar to Xmodem/CRC, except it uses blocks of 1024 bytes, rather than 128. It is faster than Xmodem, since it needs to stop less often to check for errors. This is sometimes incorrectly called Ymodem. [See also protocol, Xmodem, Ymodem].

The CTRL-S character. This is often used to pause information that is being sent. The information will be continued when an CTRL-Q is received. [See also flow control, Xon].

The CTRL-Q character. This will sometimes continue paused information.

The flow control method using the Xon and Xoff characters. It is built into the software, not the hardware.  


This is a 'catch-all' phrase encompassing the family of DSL technologies (ADSL, SDSL...)



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The file extension which refers to archives that were created by the program PKZIP. You need the program PKUNZIP to get the files out of the archive.

A file transfer protocol which is known for its speed, as well as the ability to transfer information about the files which it sends. It has crash recovery and auto-download features, and can use a 32 bit CRC, which makes it almost error-free.

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