Airtime provider
A company that sells you services provided by BT Cellnet or Vodafone. Airtime providers were instigated by the government to promote competition in the early days of cellphones. Orange and One 2 One, however, have been allowed to sell services direct to the public.

AMPS
Advanced Mobile Phone Standard. Analogue standard used widely in North America.

Analogue
The traditional way by which speech is transmitted in which the signal is continually varying. Normal fixed phones use analogue transmission. Analogue (ETACS) cellphones have rapidly been totally eclipsed by GSM phones which use digital transmission. The analogue cellphone networks are due to be phased out in the UK by the year 2005.

Authentication
Security system used on Vodafone's analogue network which is designed to eliminate cloning.

Bluetooth
A specification for short-range wireless connectivity that allows users to make easy wire-free connections (via radio link) between a wide range of communications devices. Users should become aware of the change in colour to their teeth when in the immediate area of the signals.

Caller display
System found on digital mobile phones whereby the number of an incoming caller is displayed on-screen before the phone is answered. The service is also available on fixed phones, but requires a special phone or add-on display unit, and necessitates paying BT an additional quarterly fee.

Call screening
Facility on some answering machines that allows the user to hear who's calling so they can decide whether to answer in person or not.

Cell broadcast
Service provided by digital cellphone networks where useful info is provided to users via on-screen text messages. Currently used by Vodafone and BT Cellnet to inform customers of the STD code of the area in which they are currently located - enabling them to take full advantage of local call discount schemes.

Cellular
A radio phone system in which a network of transmitters links the mobile user to the public phone system. Each transmitter covers users in its own 'cell'.

CLI
Calling Line Identification. A range of services in which the number of a caller can be accessed by the recipient. The 1471 service offered free to BT customers is one of these - as is the caller display service provided to digital cellphone users.

Clone
Whereby a 'cloned' analogue cellphone is illegally re-chipped with an ESN belonging to another. Can also refer to a phone 'badged' by one company and sourced from another. And on a more fascinating note, UK visitors may have seen a recent news article featuring 'dolly the sheep' which was born by cloning cells!

Coverage
The area in which a cellphone can make or receive calls. Coverage is usually expressed by networks as a percentage of the resident population who could use mobiles outside their own homes. Geographic coverage, therefore, is far inferior to this 'by population' figure.

CT0
The standard used by first-generation cordless phones. This analogue system can make use of just eight channels (some phones use only one), which can lead to problems with interference, particularly in built-up areas.

DCS1800
A digital cellular system operating in the 1800MHz band. Another name for PCN or GSM1800 networks.

DECT
Digital Enhanced Cordless Telecommunication (aka Digital European Cordless Telecommunication). Digital standard for cordless phones. Using 120 channels over 10 frequencies, these cordless phones offer speech quality which is vastly superior to that offered by traditional (CT0) analogue cordless phones.

Desktop charger
Cradle for holding a phone upright while it is charging. Usually also has a slot for a spare battery.

Digital
High-tech way of transmitting speech across a telephone network. The speech is sampled to create a series of 'ones' and 'noughts' (analog uses noughts and crosses or snakes and ladders) which can be transmitted, then retranslated into normal sound at the other end. One of the main advantages of digital cellphones is that they allow several cellphones in the same area to use the same frequency simultaneously.

DTMF
Facility for sending multi-frequency tones across the network from a phone. Each number, when pressed, transmits its own individual sound. Necessary for accessing some network features (such as voicemail) or for some information services.

DTX
Discontinuous transmission. Battery-saving feature found on some phones. When switched on, it conserves power by turning off transmission during pauses in speech. But it impairs sound quality.

Dual-band
Phone that can switch between two different bands of frequencies. Orange and One 2 One market dual-band phones that can switch between GSM1800 and GSM900 operation Ð allowing them to be used in a greater number of countries across the world. Dual-band handsets are also available to Vodafone and BT Cellnet customers, and could be useful in the future to solve capacity problems. Phones that can switch between GSM900 and GSM1900 operation, for use by travellers to America (the Bosch World 718 and Ericsson I888) are also now available.

Dual-mode
Phone that can operate using two different standards. Dual-mode digital/analogue cellphones are currently available in the United States. Dual-mode GSM/DECT, that can switch between cordless and cellphone communication, has recently been introduced by BT Cellnet.

Emission category
The more powerful the transmitter in your cellphone, the better it will be in giving you coverage in remote areas. Hand portable phones are Class 4 devices (as defined by the DTI) and offer maximum output of 2 Watts (although this is usually limited to 0.6 Watts). Carphones and transportables are usually Class 2 devices offering a maximum signal output of 8 Watts. If smoke is emitted, the level is too high.

ESN
Electronic Serial Number. Unique identifier transmitted by analogue cellphones.

ETACS
Extended Total Access Communications System. The standard used by UK analogue cellphones. Originally termed TACS, additional frequencies were added to increase network capacity.

ETSI
European Telecommunications Standards Institute. The people who wrote the specification for GSM and DECT.

FLMPTS
Future Public Land Mobile Telecommunications System. 21st-century mobile communications standard currently being worked on by the International Tele-communications Union. A rival to the European-backed UMTS.

Greyscale
A measure of the contrast range of a fax document. A good greyscale is important when sending photographs or coloured graphics.

GSM
Global System for Mobile Communications. A digital cellular communications standard used throughout Europe, and elsewhere around the world. The standard is used in three distinct frequency bands - 900MHz, 1800MHz, and 1900MHz. In the UK, the term GSM is commonly used to mean GSM900 - while GSM1800 networks are often referred to as PCNs.

GSM900
GSM network operating in the 900MHz band - as used by BT Cellnet and Vodafone in the UK, and by more than 100 countries around the world.

GSM1800
GSM network operating in the 1800MHz band - as used by Orange and One 2 One in the UK, and by a small but growing number of countries around the world.

GSM1900
GSM network operating in the 1900MHz band - as used in several states in the USA and parts of Canada.

Hand-over
As you move, the network transfers the handling of a call from one cell to another. The process happens automatically.

Handportable
Term used for a single-piece cellphone - what the rest of us call a mobile phone, but not to be confused with a carphone or transportable.

Hands-free
Device that allows you to use a cellphone in a car without having to hold the handset. You can then spend more time fiddling around with the car radio instead. Available as an accessory for most, but not all, mobile phones.

IMEI
International Mobile Equipment Identity. A unique serial number used on digital mobile phones.

ISDN
Integrated Services Digital Network. High quality fixed telephone line used primarily for data transfer between companies or for video conferencing. Due to be replaced soon by DSL, which will provide access speeds to the Internet around 10 to 20 times the current speeds of a 56k modem. 

LAN
Local Area Network. Communications system used by offices that connects computers to their servers, and allows employees to share files and printers.

NAM
Analogue cellphones commonly have the ability to use two or more phone numbers. A dual-NAM model could allow connection to both BT Cellnet and Vodafone's network. A quad-NAM model could allow you to handle four phone accounts from the same phone. Very rarely used feature, owing to the way in which handsets are subsidised by a particular network, and because most business users now use digital phones.

OFTEL
The Office of Telecommunications. Independent watchdog for the whole UK telephone and cellphone industry.

OGM
Outgoing message. What the caller hears when they dial your answer machine or voice-mail box.

One-touch memory
Button on a phone that allows you to dial a number just by pressing this one key. Also known as a fastkey or a 'person who can't be bothered to dial a number' key.

PABX
Private Automatic Branch Exchange. Automated multi-extension exchanges or switchboards as used nowadays by most offices

Pre-pay/Pay-as-you-go
Term used for no-contract, no rental charge services where you buy credit 'vouchers' in advance for calls. Each network has its own pre-pay service.

PBX
Private Branch Exchange. Multi-line switchboard exchange, as used in many offices.

PC card
Small accessory that allows you to connect a suitable digital mobile phone with a portable computer. Primarily designed for sending and receiving faxes and digital files (such as email).

PCMCIA card
An older term for the PC card.

PCN
Personal Communications Network. Another term for a GSM1800 network Ð such as Orange or One 2 One.

PCS1900
Personal Communications System operating in the 1900MHz band. Another name for GSM1900.

PDA (aka Palmtop computers or Pocket PC's)
Personal Digital Assistant. Older devices are referred to as palmtop computers. Newer palmtops are now referred to as Pocket PCs (confusing huh?). The Pocket PC devices are not much bigger than the average mobile phone but combine the  Microsoft Windows operating system with internet, email, MP3 and movie playback on a colour screen alongside 'pocket' versions of popular Microsoft programs. GSM facilities are expected to be added to certain models later this year.   

PMR
Private Mobile Radio. Type of mobile and walkie-talkie equipment commonly used by taxi firms, security guards, and utility companies. The advantage over cellphones is that once the equipment is paid for, and a licence is bought, there are no call costs.

PSTN
Public Switched Telephone Network. Technical term to describe the fixed, wired phone system - as operated by British Telecom.

Remote interrogation
Answering machine facility that allows messages to be retrieved from another phone.

REN
Ringer Equivalence Number. Printed on all BT-approved fixed phones and peripherals. The sum of the RENs of all devices connected to a normal wired phone line should not exceed four.

Roaming
Using your cellphone on networks other than the one to which you pay your monthly line rental. In other words, using your phone abroad. Roaming is available on all four of the UK digital networks. How many countries you can roam to will depend on the number of roaming agreements your network has signed, and on the type of phone you have access to. Roaming must be requested from your network or airtime provider.

RF
Radio frequency. Term used to describe the signal transmitted or received by a mobile phone.

RS232
Connection socket commonly found on computers. Some cellphones have the ability to be connected to a PC through this socket to facilitate the updating of personal directories, or for writing SMS text messages.

Scanner
Radio that is capable of scanning hundreds of frequencies. Used by enthusiasts to monitor PMR, emergency service, analogue cellular, and air traffic control transmissions. The essential device for the criminal who wants to clone analogue cellphones.

Scratchpad
Common feature on cellphones that allows you to store a number in a temporary memory on the handset while you are having a conversation.

SIM
Subscriber Identity Module. The smart card used in digital phones. It carries the user's identity for accessing the network and receiving calls and also stores personal information, such as a phone directory and received SMS messages. Full-size SIM cards are the same size as a credit card, while mini-SIMs are cut down to the size of a postage stamp.

SMS
Short Message Service. Two-way text messaging service is offered on all four digital networks. Messages of up to 160 characters can be sent at low cost. Some handsets only allow incoming messages (mobile-terminated SMS Ð or SMS-MT); better phones also allow you to write and send text from your handset (mobile-originated SMS, or SMS-MO). Can now be sent between phones on any network.

Softkey
Button on a mobile phone which changes function depending on what you are doing with the phone. Its current function highlighted using a keyword immediately above the button on the phone's LCD screen. An excellent system which has helped greatly in simplifying the use of cellphones. 

SOHO
Small office - Home office. Category of products or services designed to appeal to those working from home. These people are also known as teleworkers.

Standby time
The number of hours that a freshly-charged battery will keep a cellphone running without making or receiving a call. When it is switched on, power is used continuously by the phone to keep it in contact with the local cell site, so that the network knows where you are, should you receive a call.

TACS
Total Access Communications System. Original analogue standard used in the UK. See ETACS. It is also used to describe one half of a mint. The other half is called a TIC.

Talktime
The number of minutes of continuous speech that a freshly charged battery will allow you to make on a cellphone. Known in America as 'Yaddatime'.

TAM
Telephone answering machine.

TDMA
Time Division Multiple Access. Type of processing system used by digital mobile phones that allows several handsets in the same area to use the same frequency. Each conversation is allocated its own time slot Ð so that you only hear the conversation for the fraction of each second. However, as the interval between each burst of signal is small, these gaps are imperceptible to the two people having the conversation. Both GSM and DECT use TDMA to ensure efficient use of allotted
frequencies.

Telenote
Vodafone's name for its SMS service.

Teltam
Combined telephone and telephone answering machine.

Transportable
A heavyweight, two-piece mobile phone which has a high power output, for use in remote areas.

Travel charger
Small, simple charger that connects direct to a socket in the phone. Unlike with a desktop charger, there is no cradle to support the handset.

Trickle charger
A charger which takes eight or more hours to replenish the battery. Better for longevity of battery, but less convenient than fast chargers that re-power the cells in less than an hour.

UMTS
Universal Mobile Telecommunications System. 21st century cellphone standard currently being written by ETSI. The eventual successor to GSM that could go on sale as early as the year 2003. See also FPLMTS.

Voice Recognition
Facility offered by a few handsets enabling calls to be made by
using voice commands rather than punching in numbers. The memory can be programmed to store and identify names spoken into the handset and call numbers associated with them. 

Voicemail
Cellphone service provided by the networks that records a message for you when you can't, or don't want to answer a call. Unlike a traditional answerphone, the system can take messages for you when you are using the telephone

WAP (Wireless Application Protocol)
An agreed standard which enables WAP-compatible mobile phones to access Internet services (such as news, travel, entertainment, finance, sport etc) via their menu system and LCD screens. Due to the restrictions on speed and LCD screen sizes on mobile phones, WAP is mainly text based.