2G: Second Generation. 2G refers to the current generation of cellular mobile communications that employ digital modulation techniques to provide voice and low data rate services.

3GPP: Third Generation Partnership Project. 3GPP is an industry body set up to develop a 3G standard based upon wideband CDMA (WCDMA).

3GPP2: Third Generation Partnership Project 2. 3GPP2 is an industry standard set up to develop a 3G standard based upon cdma2000.

3G Third generation. 3G systems represent the generation in the development of cellular mobile communication. These systems will be digital and will be capable of supporting data rates suitable for multimedia applications.

A3. The algorithm used in authenticating subscribers to the GSM network.

AAL (ATM Adaption Layer). A protocol that translates data into a format that can be interpreted by the ATM Cell.

AAL-1 (ATM Adaptation Layer Type 1). AAL functions that support constant bit rate, time-dependent traffic such as voice and video.

AAL-2(ATM Adaptation Layer Type 2). This AAL is a placeholder for variable bit rate video transmission.

AAL-3/4 (ATM Adaptation Layer Type 3/4). AAL functions that support variable bit rate, delay-tolerant data traffic requiring some sequencing and/or error detection support. Originally two AAL types, that is, connection-oriented and connectionless, which have been combined.

AAL-5 (ATM Adaptation Layer Type 5). AAL functions that support variable bit rate, delay-tolerant connection-oriented data traffic requiring minimal sequencing or error detection support.

AB (Answer Back). A signal from a receiving device that indicates that it is ready to receive data.

Abandoned call. A call that enters the telecommunications network but is terminated by the subscriber before it is answered.

Access fee. The fee paid by cellular subscribers to their carrier for any connections to the local PSTN. The carrier, in turn, pays the local PSTN for the use of their circuits to connect the call.

Access line. The telephone line that connects a call into the switching center (local exchange) of a network.

AC-DC ringing. A technology that uses an alternating current to ring a telephone and a direct current to cease ringing when the telephone is answered.

Acoustic coupler. Equipment used in the conversion of electrical signals into audio signals in order to transmit data over a PSTN.

ACR (Allowed Cell Rate). The rate at which a transmitter is allowed to send signals in ATM systems - measured in cells per second.

ACTS: Advanced Communication Technologies and Services. ACTS was a research program promoted by the European Commission to develop advanced communications technologies.

AD (Abbreviated Dialing). Entering a two-digit or four-digit number into a terminal which has been pre-programmed to recognize the number as an abbreviation for a frequently dialed number which can be automatically dialed by the switching center (local exchange).

Adaptive equalization. The ability of an audio modem to detect variations in signal quality on a telephone line and take steps to compensate for it.

Add-on conference. A system that allows a telephone user to introduce another telephone user into an existing conversation.

Administrative domain. A collection of functional entities in a network that are grouped for administrative purposes.

AFI (Authority and Format Identifier). Included in the header of a transmitted packet. It identifies the format of the incoming message for the receiver.

Aggregate bandwidth. Describes the entire bandwidth of a channel used in a multiplexed bit stream.

Aggregate discount. A discount given to subscribers of multiple optional services based on the aggregate cost of the services.

All number calling. Telephone numbers that contain no letters just numerical digits.

Altair. The name given by Motorola to their wireless local area network.

Alternate routing. A mechanism that supports the use of a new signal path after an attempt to transmit the signal down a previously selected path fails.

AIN (Advanced Intelligent Networks). Networks using sophisticated devices to facilitate roaming by subscribers outside of their home location area.

Airline mileage. The distance in miles between two terminals in a network.

Airtime. The time a subscriber spends on a call.

Algorithm. A procedure or formula used to solve a problem.

Allocation. The designation of a band of frequencies for a specific radio service such as GSM.

Alphanumeric. A message such as SMS that can contain both letters (alpha) and numbers (numeric).

Ambient noise. A noise level that is always present.

Amplifier. A device that strengthens the signal of an analog transmission. As an analog signal moves further from its point of origin, it weakens in strength, so amplification is required to restore the signal quality for the receiver.

Amplitude. The distance between the high and low points on a signal or waveform.

AMPS (Advanced Mobile Phone System). The U.S. technical standard for an analog mobile phone system.

Analog. A method that uses variations in frequency to carry signals. Analog means 'analagous' or 'copy of'. Analog technology transmits voice signals in the form of electrical signals whose frequency and amplitude are proportional to the vibrations in the voice. Traditional wireless telephones use analog technology.

Analog cellular. The standard for equipment using cellular telephones using radio wavelengths to transmit telephone calls.

Analog channel. A channel that has no limitations on the amount of data it transmits.

Analog signal. In wirless telecommunications, a continuous signal that reflects variations in loudness of a human voice.

Ancillary charges. Charges for optional services delivered by a carrier.

ANSI (American National Standards Institute). A voluntary standards organization of the USA and is a member of the International Standards Organization (ISO). It is a clearing house for standards, generally adopting standards proposed by smaller companies and organizations within the USA.

ANSI-41. A US core-network standard developed to support roaming between different cellular systems.

ANSI emulation. The ability of a device to send, receive, and display ANSI (American National Standards Institute) graphics.

Antenna. A device that both transmits and receives radio frequencies.

Antiope. The teletext system used in France.

AOSP (Alternate operator service provider). Organizations other than local exchange carriers (LEC) that provide operator services for long distance calling.

APCM (Adaptive pulse code modulation). A technique used to share occupied bandwidth among a maximum number of subscribers during peak times by reducing the signal sampling rates of each subscriber.

API (Application Program Interface). A programmating interface used for the inter-programming of communications or interfaces between protocol layers.

Application. Software that performs tasks for the user directly, for example, database applications or word processors.

Application Layer. The seventh layer of the OSI model, which contains user applications, and serves as the interface between the user and the communications technology.

AR (Alternate Route). A secondary path for signal transmission if the primary path is unavailable.

Architecture. The description of how a system's component parts interact and the protocols and interfaces used for communication throughout the system.

Area code. A number dialed before the desired telephone number that allows the subscriber who is outside a specific area to connect directly with the desired number.

ARIB: Association of Radio Industry and Business. ARIB is a Japanese standards organization.

ARP (Address Resolution Protocol).

Artifact. Imperfections that can arise during the processing of digital signals.

ASCII. A parity-bit code approved by ANSI to establish a uniform means of communication between data processing systems, communications systems, and terminal equipment.

Asymmetrical modulation. A technique used for high-speed transmission where a modem uses most of the bandwidth in a call for transmission, while using only a small part for reception.

Asynchronous Time Division Multiplexing. A multiplexing technique in a transmission capability is organized into unassigned time slots. The time slots are assigned to cells upon request of each application's instantaneous real need.

ATM (Asynchronous Transfer Mode). A standard for high-speed transfer of integrated media types - voice, video, and data - all on the same communications medium. ATM is a connection-oriented technique that requires information to be buffered and then placed in a cell. When there is enough data to fill the cell, the cell is then transported across the network to the destination specified within the cell. ATM cells are much smaller than standard packet-switched networks, which means that less bandwidth is required for signal transmission.

AT&T. A long distance inter-exchange carrier in the United States.

ATM Cell. A unit of transmission in ATM. A fixed-size frame consisting of a 5-octet header and a 48-octet payload

ATM Layer Link. A section of an ATM Layer connection between two adjacent active ATM Layer entities.

ATM Link. A virtual path link (VPL) or a virtual channel link (VCL).

ATM Peer-to-Peer Connection. A virtual channel connection (VCC) or a virtual path connection (VPC).

ATS (Abstract Test Suite). A set of abstract test cases designed to test a particular protocol.

Attenuation. The weakening of transmitted signals as they travel further from their point of origin. Attenuation occurs in both analog and digital systems.

AU (Alternate Use). The ability to alternate between various communications services, for example, from voice tranmission to data transmission.

Author. A person or software program that generates WML or WMLScript .

AVD (Alternate Voice Data). A single tranmission facility that can be used for either voice transmission or data transmission.

AuC (Authentication Center). A component of the infrastructure equipment in the GSM network. Its purpose is to validate subscribers logging on to the network. It does this by means of a secret key. The AuC contains a unique key (code) for each subscriber in a network. The subscriber has a copy of this key within the SIM card. A subscriber attempting to log on to the network is sent a copy of a random number by the AuC. The secret key within both the SIM card and the AuC changes their copy of the number. The number produced by the SIM card is returned to the AuC and if it is the same as the number produced by the AuC the subscriber is validated and is allowed access to the network.

Audible signal control. The controlling of the volume of set signals such as the ringing signal and dial tones.

Audio frequencies. Frequencies that can be heard by the human ear, normally between 30 Hz and 20,000 Hz.

B-ICI (B-ISDN Inter-Carrier Interface). An ATM Forum defined specification for the interface between public ATM networks to support user services across multiple public carriers.

B-ISDN (Broadband ISDN). A high-speed network standard (above 1.544 Mbps) that evolved narrowband-ISDN with existing and new services with voice, data and video in the same network.

Backbone. The network of broadband connections between the infrastructure equipment on a network.

Billing account number. A number used by carriers that identifies the subscriber that will be billed.

Band. The range of frequencies within two defined limits.

Bandwidth. The range of frequencies a signal needs for its successful transmission. The broader the bandwidth, the greater the information-carrying capacity of a channel. In digital systems, bandwidth is measured in bits per second (bps). In analog systems, it is measured in hertz.

Base rate. A nondiscounted charge for a basic telephone service.

Baud. The traditional term (seldom used now) for measurement of data rate over a link.

Bearer service. A service that provides the underlying network capacity, necessary for transmission to occur, between two points in the same or different networks.

Binary. The base two numbering system that digital systems use to represent data. It consists of just two numbers: "0" and "1".

Bit. The smallest unit of data in digital systems, having a binary value of either 0 or 1. Bits are normally stored in multiples called bytes.

Bit duration. A technique used to measure delay times in the transfer of digital signals through a transmission medium. In essence, the bit duration is the time measurement for a signal bit to pass a specified point.

Bit error rate. The ratio of the number of bits received in error on a digital link to the total number of bits received.

Block. A group of seven cells.

Blocked call. A call that enters the network but does not reach the requested destination. Normally due to network problems.

bps (Bits per second). In digital communications systems, the data rate is measured in bps.

Broadband. A communications channel with a bandwidth of more that 674 kbps (kilobits per second) normally used for high-speed data communications over standard telephone circuits.

Broadband access. An ISDN access capable of supporting one or more broadband services.

BS (Base Station). In a cellular radio network, the base station (BS) is used for the transmission and reception of the radio signals between the mobile terminal (i.e. the mobile phone) and the network.

BSC. The Base Station Controller is the network node that connects the Base Transceiver Station (BTS) and the Mobile services Switching Center (MSC).

Base Station Subsystem (BSS). A system comprised of the Base Station Controller (BSC) and the Base Station Transceivers (BTS) in GSM.

BTS. The Base Transceiver Station is composed of an antenna and transceiver. The BTS handles the radio interface with the mobile phone. It is the first entity within the GSM network that detects the mobile signal. The parameters of a cell are defined by the transceiver signal strength of the BTS.

Bundling. The merging of more than one service rate into a single rate. For example, paying for a particular service and receiving another service at a reduced cost. The two services are only sold as a unit and not individually.

Byte. A unit in which bits are stored. In most digital systems a byte is 8 bits long. The abbreviation of byte is "B" and bit is "b".

Bytecode. This is content encoding where the content is a set of low-level instructions for a specific device.

Byte rate. The speed of digital transmission measured in bits per second.

C band. The bandwidth between 4 GHz and 6 GHz on the electromagnetic spectrum used for satellite transmissions.

C-Message noise. The noise level which can be detected on a channel in the absence of a signal.

CAI Common Air Interface. The CT2 mobile communication standard (equivalent to GSM) that allows any mobile terminal equipment to be used.

Call answering . A service provided by GSM that answers a call automatically if the subscriber is not available to receive the call. The caller will either be told that the subscriber is not available or, if the subscriber has subscribed to the short messaging service, (SMS), the caller will be given the option to leave a message.

Call card. A prepaid card or credit card issued by carriers for the purpose of making telephone calls.

Call center. A central place where all calls to a network are handled.

Call forwarding. A service provided by GSM that routes calls from the mobile terminal directly to another telephone number.

Call log. A feature that allows you to see the status of the last outgoing and incoming calls on the mobile terminal display and to automatically dial any number on the call log.

Call processing. A sequence of operations performed by the switching system from the time the call is accepted to the end of the call.

Call progress tones. Signals sent by the switching equipment to the subscriber, that indicate the status of the call, for example, engaged tones and dialing tones.

Call setup time. The time taken for a switched call to reach the called party.

Call waiting. A supplementary service that allows an existing call to be put on-hold in order to answer another incoming call, and then alternating between the two calls.

Called party. The subscriber that receives a telephone call (also known as the B-subscriber).

Calling party. The subscriber who makes the telephone call (the A-subscriber).

Capacity. The highest possible transmission speed that can be achieved on a channel without affecting the quality of the signal.

Card. A single WML unit of navigation and user interface. It may contain either information that is to be presented to the user, request input from the user etc.

Carrier. A provider of a wireless cellular telecommunications service.

CBR (Constant Bit Rate). An ATM service category which supports a constant or guaranteed rate to transport services such as video or voice as well as circuit emulation which requires rigorous timing control and performance parameters.

CCITT. CCITT is the International Telegraph and Telephone Consultative Committee, a standards body. CCITT is the former name for the ITU-TS (International Telecommunications Union - Telecommunications Sector).

CDG (CDMA Development Group). An industry association set up in 1994 to promote the world wide development, implementation and use of the IS-95 CDMA standard under the brand name of cdmaOne.

CDMA (Code Division Multiple Access). A method of digital communication that enables a number of cellular conversations to be transmitted on a single radio frequency. CDMA gives each conversation a numerical code that ensures that the correct signal is received by the called party.

cdmaOne. A brand name, trademarked and reserved for the exclusive use of CDG members that describes a complete cellular wireless systems. It incorporates the IS-95 CDMA air interface and many other standards that make up a complete wireless system.

cdma2000. A system proposed by the CDG for 3G services. It is based upon an evolutionary outgrowth of cdmaOne to allow operators a migration path from second generation cdmaOne system to third generation cdma2000 systems.

cdma2000/1XRTT. An implementation of the multi-carrier cdma2000 standard that uses 1x1.25 MHz carrier.

cdma2000/3XRTT. An implementation of the multi-carrier cdma2000 standard that uses 3x1.25 MHz carriers.

CDR (Call Data Record). A record produced by the mediation device of all toll tickets generated during a call.

Cell. The geographical area covered by a Base Transceiver Station (BTS). Another kind of 'cell' with a different meaning is an ATM cell.

Cell Header. ATM Layer protocol control information

Cell site. The physical structure that contains the control equipment required to connect a mobile station with the switching network. In the GSM network, the cell site is otherwise known as the Base Transeiver Station (BTS).

CEPT (Conference Europeene des Administrations des Postes et Telecommunications). CEPT was prominent in the development of European telecommunications up until 1988 when it handed over its technical standard development activities over to the European Telecommunications Standards Institute (ETSI).

Channel. A 'pipe' that carries a signal frequency.

Channel grade. The indicator of the relative bandwidth of a channel, that is, narrowband, broadband, voice grade.

Channelizing. The subdivision of broadband systems into a number of smaller channels.

CLI (Calling Line Identification). A supplementary service available in digital phone networks that allows the caller's number to be displayed on the mobile terminal display. The call management center achieves this by using equipment that identifies the caller's telephone number and sends it to the subscriber in addition to the call.

Client. The device that initiates a request for connection to a server.

CLP (Cell Loss Priority). This bit in the ATM cell header indicates two levels of priority for ATM cells. CLP=0 cells are higher priority than CLP=1 cells. CLP=1 cells may be discarded during periods of congestion.

CPCS (Common Part Convergence Sub-layer). The part of the convergence sub-layer of an AAL that remains the same regardless of the traffic type.

CPCS-SDU (Common Part Convergence Sub-layer-Service Data Unit). A protocol data unit to be delivered to the receiving AAL layer by the destination CP convergence sub-layer.

CPE (Customer Premises Equipment). End-user equipment that resides on the customer's premises and which may not be owned by the local exchange carrier.

Cluster. A cluster is defined as a group of cells that use all of the available frequencies allocated to the network operator.

Codec (COder/DECoder). It converts analog to digital signals and vice versa. Codec technology is most commonly used in modems.

CRC (Cyclic Redundancy Check). CRC is a technique employed for error control in digital communications systems.

CS (Convergence Sub-layer). The general procedures and functions that convert between ATM and non-ATM formats. This describes the functions of the upper half of the AAL layer and is also used to describe the conversion functions between non-ATM protocols such as frame relay or SMDS, and ATM protocols above the AAL layer.

D-AMPS (Digital Advanced Mobile Phone System). The U.S. technical standard for digital mobile phone system.

Data compression. The general term for the various algorithms and programs developed to transmit data in a format that saves storage space. A compression program is used to convert data from the original format to one optimized for compactness. A decompression algorithm returns the information to its original format.

Datagram. Another term used to describe an information packet.

Datalink layer. The second layer of the OSI model for data communications. The datalink layer contains protocols for the construction of frames, frame addressing, and the detection of errors on a link.

Data rate. The amount of information that can be sent down a channel in a given time. In analog systems, data rate is measured in terms of bandwidth. In digital systems, it is measured in bits per second.

dB (decibel). A logarithmic measure of relative signal strength which is a convenient means of describing signal powers that vary over a very wide range of values.

DDS Direct Digital System. A network whose infrastructure equipment is completely digital. All signals on such a network are transmitted digitally and there is no need for analog-to-digital converters.

Deck. A collection of WML cards.

DECT (Digital Enhanced Cordless Telecommunications). A digital standard for wireless telecommunications. Unlike GSM, which is suited when roaming over large geographical areas, DECT is designed for a smaller area such as a city. DECT is becoming increasingly popular as an alternative for homes and business, to the ordinary fixed network telephone service. DECT uses TDMA to transmit radio signals within the network. A user can have a telephone (known as dual-mode phone) that can seamlessly operate with both GSM and DECT.

Device. A network entity that is able to transmit and receive information packets.

DID (Direct Inward Dialing). Making a call directly to a desired extension number without needing to speak with the switchboard operator.

Digital. A method of transmitting voice signals or data. Digital signals are represented in binary format.

Data line interface. The connection point for a telephone.

Downlink. The transmission of radio frequency (RF) signals down a hierarchy of infrastructure equipment. For example, from a satellite to a ground communications station, from a mobile services switching center (MSC) to a base station controller (BSC); from a BSC to a base transceiver station (BTS).

DSP (Digital Signal Processing). DSP is a modern digital technique for processing signals. It allows complex operations to be performed very cost effectively through the use of microprocessor-based integrated circuits.

DS-CDMA: Direct Sequence CDMA. DS-CDMA is a form of spread spectrum modulation.

DS-SS (Direct Sequence-Spread Spectrum). DS-SS is a form of spread spectrum modulation in which the narrowband information-bearing signal is spread over a wide range of frequencies through direct multiplication with a pseudo-random binary sequence.

DT (data Terminal). Any equipment that acts as a source of data signals or a receiver of data signals.

Dual-mode phone. A phone that can operate on both analog and digital networks.

Duplex. Simultaneous, bidirectional independent transmission of data.

E.164. A public network addressing standard utilizing up to a maximum of 15 digits. ATM uses E.164 addressing for public network addressing.

E-AMPS (Extended AMPS). E-AMPS is an extended form of the AMPS system in which the number of available radio channels has been increased to 1023 through an increased spectrum allocation.

Earth station. A satellite communications device located on the Earth's surface.

Echo cancellation. A technique used in analog systems that isolates and filters interference from voice circuits.

Echo canceller. A device that removes interference from a speech channel. Echo cancellers cannot be used with some types of high speed modem calls and ISDN.

Echo suppressor. A device that attenuates the transmission path in the opposite direction to the transmitted signal in order to prevent reflected energy being echoed back to the signal transmitter.

EDGE (Evolved Data rates for GSM Evolution). Evolved Data Rates for GSM Evolution.

EIA (Electronics Industries Association). The EIA is a national trade association, developing electrical standards primarily for North America.

EIA/TIA (Electronics Industries Association and Telecommunications Industries Association). An organisation in the United States consisting of two merged associations - the EIA and the TIA. The EIA is concerned with the specification of standards for hardware interfaces.

EIR (Equipment Identity Register). A database containing a list of all valid IMEIs on the network.

Each IMEI is given a colour code that indicates its status.

1. A white-listed IMEI means that the terminal is allowed to connect to the network.
2. A grey-listed IMEI indicates that the network is currently watching the terminal for possible problems.
3. A black-listed IMEI means that the terminal is not allowed to connect to the network, because it has either been reported stolen or is the wrong type of terminal for that particular GSM network.

Electromagnetic spectrum. The complete range of wavelengths of electromagnetic radiation available.

E-mail Electronic mail. The transmission and reception of computer-stored messages by telecommunication. E-mail is the most popular facility on the Internet.

EMI (Electromagnetic interference). Signals that are radiated from electronic equipment that surround a subscriber such as computers that interfere with the signal quality of a call.

Encryption/Decryption. Encryption is the scrambling of a communication signal for security purposes. Algorithms act on the signal to encrypt it before it is transmitted. When the signal is received, an algorithm is used to decrypt the encrypted signal.

ESN (Electronic Serial Number). In US cellular systems, all mobile handsets have a unique ESN which is assigned at the time of manufacture. It is a permanent and unique identification number for mobile handsets.

ES (End-System). A system where an ATM connection is terminated or initiated. An originating end-system initiates the ATM connection, and terminating end system terminates the ATM connection.

ESS (Electronic Switching System). A system used in telecommunications networks to switch call signals to the desired destination.

ETR (Effective Transfer Rate). The maximum rate at which data can be sent after the data has been opimized for transfer by processes such as data compresssion.

ETSI (European Telecommunications Standards Institute). ETSI was founded in 1988 under the direction of the European Commission. Since 1988, the CEPT has gradually transferred its role in developing standards for European telecommunication over to ETSI.

External handover. Handover between...

1. Cells under the control of different BSCs but belonging to the same MSC.
   
2. Cells under the control of different MSCs.
   

Facility. A single functional entity in a network.

Facsimile (fax). A means of transmitting documents using telecommunications circuits with a device that scans the document and uses coded signals to transmit the document content to another destination.

Facsimile server. A server that allows a number of users on a computer network to use the same fax machine.

Fading. The reduction in intensity of a signal or part of a signal.

Fax modem. A modem with fax transmission and reception capabilities.

FCC (Federal Communications Commission). A U.S. government agency primarily responsible for the allocation of radio spectrum for communications services in the United States.

FDD (Frequency Division Duplexing). In a FDD system simultaneous transmission and reception of radio signal is possible. This allows the mobile phone user to talk and listen at the time. The mode of communication is facilitated by having a frequency channel with two separate operating frequencies, one for transmission and the other for reception.

FDMA (Frequency Division Multiple Access). The process of dividing bandwidth into multiple frequencies which can be shared out among base transceiver stations (BTS)within the network.

Features. Inherent benefits offered by a product.

FH-SS (Frequency Hopping-Spread Spectrum). FH-SS is a form of spread spectrum modulation in which the narrowband information-bearing signal is spread over a wide range of frequency by hopping its carrier frequency in a pseudo-random pattern.

FIFO (First In/First Out). A call queueing technique where the call that enters the queue first is dealt with first.

Filter. A device that can distinguish a desired signal from interference and supresses any interference.

Flag. A unique bit pattern used in TDMA that identifies the beginning or the end of a frame.

Flat rate service. A service charged at a fixed price regardless of usage, for example, line rental.

Flexible line ringing. The use of different ringing tones for different lines within an organization.

Forward channel. A one-way communications path that carries signals from the calling party to the called party.

Frame. A vehicle for the transmission of data over a link. It can be described as a collection of bits, including the address, data, and control information, that is switched and transmitted over a link. The size and composition of the frame varies according to the protocol used. The terms packet and frame are often used interchangeably.

FRAMES: Future RAdio wideband Multiple AccEss System. FRAMES was a project undertaken under the ACTS programme to develop the UMTS air interface.

Frequency. The speed of an electromagnetic transmission. Frequency can be defined as the number of cycles per second of an electromagnetic transmission usually measured in hertz. Generally, high frequency transmissions can carry more information at greater speeds than low frequency transmissions.

Frequency group. In cell planning, a frequency group is a set of frequencies allocated to each cell, and is determined by the network operator. In a cluster, different sets of frequencies are allocated to neighboring cells.

Frequency Re-Use. In a PLMN, the ability of two base transceiver stations to use the same group of frequencies for transmitting and receiving, provided they are a sufficient distance apart.

Full duplex transmission. A communications circuit that can transmit and receive information simultaneously.

G3G: Global Third Generation. The G3G proposal was developed by the OHG in order to harmonize the WCDMA systems being proposed by 3GPP and 3GPP2.

Gain. A measure of amplification - in decibels (dB).

Gateway. A device that connects two or more dissimilar networks and allows communication between them.

Gbs (Gigabits per second). The rate at which data can be transferred along a communications link. 1 Gbs is equal to one billion bits per second or approximately 125 million characters per second (where each character is equal to 8 bits).

GFC (Generic Flow Control). A field in the ATM header which can be used to provide local functions (for example, flow control). It has local significance only and the value encoded in the field is not carried end-to-end.

GGSN: Gateway GPRS Support Node. The GGSN is a network component within the GPRS system.

GHz. A unit of frequency equal to one billion hertz or one thousand megahertz.

GMSC (Gateway Mobile services Switching Center). GMSC acts as a gateway for incoming calls into a GSM network.

GPRS: General Packet Radio Service. GPRS is a packet based data service developed for mobile communications systems that will support data rates of up to 115 kbps.

GPS (Global Positioning System). GPS is a satellite-based navigation system operated by the US Department of Defense (DoD). The space segment of the GPS system consists of 24 satellites placed in 6 orbital planes that orbit the earth every 12 hours.

GSM service area. The GSM service area is the entire geographical area in which a mobile subscriber can access a GSM network.

Group 1 fax. An analog facsimile that can transmit a standard page within 6 minutes. Group 1 machines are no longer manufactured.

 

Group 2 fax. An analog facsimile that can transmit a standard page within 3 minutes by using data compression techniques.

Group 3 fax. A digital facsimile that can transmit a standard page in under 1 minute. Group 3 facsimiles are standard in business. They can detect the maximum transmission and reception capabilities of a group 1 or group 2 fax and alter its settings to suit.

GSM (Global System for Mobile communications). A digital system for cellular telecommunications.

 

GSM Bearer. Refers to the various mechanisms the GSM network uses to transmit voice and data.

GSM MAP: GSM Mobile Application Part. GSM MAP is the core network that supports the GSM air interface.

Guard tone. A feature of high speed modems that uses a special tone to detect if there is sufficient bandwidth available on a PSTN network for transmission.

Half-duplex transmission. A communications circuit that can transmit and receive information but not simultaneously.

Handover. The switching of a mobile signal from one channel or cell to another. There are two categories of handover, Internal handover and External handover.

Handset. The hand-held telephone terminal containing a transmitter and receiver.

Handshake. An exchange of signals between two connected devices to ensure that the connection is maintained.

HCS: Hierarchical Cell Structure. HCS is a technique that uses a combination of overlaid micro- and macro-cells to increase the capacity within a cellular network.

Header. Information attached to the first frame of a message. It carries information to the receiving device about the message itself, the message's destination, and routing information.

Headset. A device that contains the same technology as a handset but is worn on the head to keep the hands free.

HEC (Header Error Control). Using the fifth byte (octet) in the ATM cell header, ATM equipment may check for an error and corrects the contents of the header. The check is calculated using a CRC algorithm allowing a single-bit error in the header to be corrected or multiple errors to be detected.

HEO Satellites (High Earth Orbit Satellites).

HF (High Frequency) . Frequencies in the 300 to 30000 KHz range.

High frequency bands. Frequency bands above the audible frequencies.

High speed. Data transmission rates in excess of 9.6 Kb/s.

Hold. A feature that allows the called party to exit a call briefly without the call being disconnected.

Hop. In cellular telecommunications, a switch from one radio frequency RF channel to another.

Hertz. The measurement of bandwidth in analog devices.

HLR (Home Location Register). A database containing subscriber information files about the subscriber and the current location of a subscriber's mobile station.

HSCSD: High Speed Circuit Switched Data. GPRS is a circuit switched data service developed for mobile communications systems that will support data rates of up to 57 kbps.

HTML (Hypertext Markup Language). HTML is a standard recommended by the W3C and defines a set of "markup" codes (or tags) that are inserted into a file which is intended to be displayed on a World Wide Web browser. The codes inform the browser how the text and images are displayed for the user.

HTTP (Hypertext Transfer Protocol). A protocol or set of rules for exchanging files including text, images, sound and video on the World Wide Web (WWW).

IAS (Interconnect Account Systems). When a call is made from a subscriber network to another network, the other network will bill the subscriber's network. IAS gathers and processes call data, both in and out of a network - creating Accounts Receivable and Accounts Payable databases. Accounts can then be settled between each network at a later date. This system is implemented when there is a wholesale rating contract between the networks.

IDN (Integrated Digital Nework). A switched network that transmits voice using digital transmission techniques.

IETF (Internet Engineering Task Force). An international community of network operators and designers, vendors, and researchers concerned with the evolution of the Internet architecture and its operation.

IMEI (International Mobile Equipment Identity). A code that uniquely identifies the mobile terminal hardware. It is important in GSM for keeping a record of lost or stolen mobile telephones. A copy of each IMEI is stored in the EIR

IMSI (International Mobile Subscriber Identity). A unique number within the SIM card that identifies the subscriber to the system.

IMT-2000. An initiative undertaken by the International Telecommunications Union (ITU) to establish a global standard for third-generation wireless multimedia communications.

Informations systems network. A network of all the communications systems within an organization.

Infrastructure equipment. The fixed transmitting and receiving equipment in a communications system. It normally consists of base transceiver stations (BTSs), base station controllers (BSCs), switches, computers, and all other equipment that sends and receives signals from mobile equipment and/or the public switched telephone network (PSTN).

Inter-exchange channel. A link between two or more telephone exchanges.

Intercept treatment. A function carried out by a telephone switching exchange that involves the redirection of a call signal (that cannot be connected to the desired destination) to a recording or an attendant.

Interface. A means of connection between two or more entities, for example, a graphic user interface (GUI) is the means of connection between a computer and a person.

Interference. Radiated energy such as EMI that interferes with radio signals, causing diminished reception quality.

IS: Interim Standard. A series of standards recommendations from ANSI.

Interim Standards. A set of protocols for cellular telephony in the United States. They include:

• IS-41 (Interim standard-41). The protocol for roaming within the United States. Determined by the Telecommunications Industry Association (TIA).
• IS-54 (Interim standard-54). A North American dual-mode (analog and digital) cellular standard. In the analog mode, IS-54 conforms to the AMPS standard.
• IS-95 (Interim standard-95). The CDMA standard for the U.S. digital cellular service.
• IS-136 (Interim standard-136). The TDMA standard.

 

Internal Handover. Handover between:

1. Channels within the same cell.
   
2. Cells that are under the control of a single BSC.
   

 

Internet telephony. The use of the Internet rather than the traditional telephone company infrastructure to exchange telephone information.

IP (Internet Protocol). A method (protocol) used to send data from one computer to another on the Internet. Each computer (known as a host) on the Internet has an address that uniquely identifies it. The data is sent in packets, which contain the sender's Internet address and the receiver's address.

ISDN (Integrated Services Digital Network). A digital network which today is found integrated with the PSTN network and can carry voice and data.

IS-95. IS-95 defines the radio link or air interface between the mobile station (MS) and base station (BS) in cdmaOne networks.

IS-97. IS-97 defines the functionality of the base station (BS) in cdmaOne networks.

IS-98. IS-98 defines the functionality of the mobile station (MS) in cdmaOne networks. For example, speech encoding and power control.

ISO (International Standards Organization). The ISO is a voluntary organization composed and financed by the national standards organizations of its member countries. ISO standards cover every conceivable item possible not just telecommunications.

ITU (International Telecommunications Union). The ITU is an agency of the United Nations and is responsible for overseeing all aspects of telecommunication.

ITU-R: International Telecommunications Union Radiocommunication Bureau. The ITU-R is a part of the ITU that regulates the assignment of radio frequencies throughout the world and it also acts as a consultative committee for the development of radiocomunications standards.

Javascript. A de facto standard language that is used to add a dynamic element to HTML documents.

JPEG (Joint Photographic Experts Group). A protocol defined by the International Standards Organisation (ISO) and supported by the World Wide Web for the compression of still video graphics. In creating JPEG images a trade-off is usually made between the image's quality and file size that will allow the image to be transmitted quickly.

K56flex. A modem that can transmit data over ordinary telephone lines at a rate of 56 kbps (thousand bits per second).

KA band. The band width in the 20 to 30 GHz range.

kpbs. A measurement of data rate in thousands of bits per second that that travel through a channel in one second.

Kermit. A communications protocol used for file transfer or for terminal emulation.

Key pulsing. A telephone system that requires the caller to use the telephone key pad to dial a number.

Kilohertz. A measure of electromagnetic frequency in thousands of cycles per second. 1 KHz is equal to 1000 cycles per second.

Ku Band. The bandwidth in the 11 to 14 GHz range used for medium-power satellites.

LB (Leaky Bucket). A term used as an analogous description of the algorithm used for conformance checking of cell flows from a user or network. The "leaking hole in the bucket" applies to the sustained rate at which cells can be accommodated, while the "bucket depth" applies to the tolerance to cell bursting over a given time period.

LAI (Location Area Identity). LAI identifies a location area.

Land line. The telephone service or (PSTN).

Land mobile service. A bidirectional radio service within the 44-50 MHz bandwidth.

Latency. A term used to typically describe delays in a network. For example, congestion, routing etc.

Layer. The open system interconnection (OSI) model of seven layers that defines the protocols for data communications.

Layer 1. In the (OSI) model, the physical layer which represents the hardware used for communication.

Layer 2. In the (OSI) model, the datalink layer is concerned with the optimization of data for transmission.

Layer 3. In the (OSI) model, the network layer is concerned with the routing and switching of data from its source to its destination.

Layer 4. In the (OSI) model, the transport layer which represents the processes involved in establishing connections throughout the network and the control of the transmission of data within the network.

Layer 5. In the (OSI) model, the session layer is concerned with establishing a connection between communication devices. This layer is also responsible for the termination of a conversation/session when the devices have finished communicating.

Layer 6. In the (OSI) model, the presentation layer is concerned with the presentation of data at the receiving end of the link. It is responsible for the encryption/decryption of data and data compression. The presentation layer is primarily concerned with passing data into the network in a suitable format.

Layer 7. In the (OSI) model, the application layer which contains the user applications. The application layer is the interface between the user and the communications technology.

L-band. The bandwidth of the electromagnetic spectrum used for satellite and microwave communication signals.

LCD (Liquid Crystal Display).

LIFO (Last In/First Out). A queueing technique where the last entry to the queue is the first to be removed.

Link. An entity that defines a topological relationship (including available transport capacity) between two nodes in different sub-networks. Multiple links may exist between a pair of sub-networks. It is synonymous with logical link.

Local exchange area. The part of the national land telephone network controlled by the local telephone operating company.

LEC (Local exchange carrier). A landline telephone company serving a local area.

Location Area. A group of cells uniquely identified by its Location Area Identity (LAI) number.

Location updating. When the mobile station is roaming, it is continually listening to the control channel from the base transceiver station (BTS), which is transmitting the location area identity (LAI). When the mobile station enters a new location area or MSC service area, it recognizes a new LAI and will inform the network, the VLR and HLR, of its new location. This is known as location updating.

Loopback test. A circuit test of any device involved in the transmission or reception of signals to ensure it is in working order and that the device and the interface are working together.

Macrocells. Cells which are used mainly where few base transceiver stations are required to provide coverage for remote or sparsely populated areas. These cells typically have a radius between 10-35 km.

MAHO (Mobile Assisted Handoff). MAHO is an example of decentralized call processing where signal strength measurements performed at the mobile terminal are used to decide when handoff is to occur.

Manual exchange. A telephone exchange that uses an attendant to manually connect calls.

Master agent. An employer of agents who sell telecommunications services.

Master station. A telecommunications station that controls all other stations within a network.

Matrix. A network switch that connects calls from their source to their requested destination.

Matrix switching. A type of switching used with ATM to allow the use of the required bandwidth for the duration of a connection.

Mbps: Megabits per second. A convenient measure of the data rate in digital communications systems is the number of millions of bits per second transmitted.

MC-CDMA: Multi-carrier CDMA. A variant of CDMA based upon the use of multiple frequency carriers. It is used in the cdma2000 specification.

Measured rate service. The charging for a telecommunications service based on the frequency of usage of the service.

Mediation device. Located between the MSC and the billing and rating system, it collates all the toll tickets generated by a single call producing a call data record.

Medium. The pathway that carries a signal. Wireless telecommunications use radio waves as media whereas non-wireless media includes, for example, cables and fibers.

Medium frequency. A frequency within the 300 to 3000 KHz range.

Medium speed. The transmission of data at speeds between 2,400 bps and 9,600 bps. Voice signals are transmitted at speeds of 9,600 bps and above.

Megahertz (MHz). A measurement of frequency equal to one million cycles per second. One cycle per second is one hertz.

Message control packet. The control information sent with a message that is necessary for the transmission and reception of a message between two communication devices.

Microbrowser. Client software that is designed to overcome the restrictions of wireless handheld devices and allows access to a range of information services such as the Internet.

Microwave. Radio frequency signals between 890 MHz and 20 GHz.

Microcells. Microcells are used for urban or densely populated areas where the traffic is too high for macrocells. These cells typically have a radius up to 2 km.

MIN (Mobile Identification Number). The MIN represents the telephone number of the mobile handset. It is the number that must be dialed in order to reach the mobile subscriber.

Mobile Equipment (ME). The term used to refer to a handset. A mobile station is comprised of the mobile equipment and a subscriber identity module (SIM).

Mobile signal. The signal transmitted from the mobile terminal.

Mobile Station (MS). A mobile station is used by the subscriber to communicate with the GSM network and consists of the mobile equipment (ME) and the subscriber identity module (SIM).

Mobile terminal. The handheld mobile phone.

Mobile terminal display. The window or display on each mobile telephone that indicates the status of the mobile connection.

MS (Mobile Station). The MS is the mobile terminal (that is, the mobile phone) used by the subscriber to access the cellular network.

MSC (Mobile services Switching Center). The hub of the network system. Its main purpose is to control calls to and from other telephone and data systems such as PSTN. It plays a major role in subscriber roaming by providing all the necessary functionality involved in registering, authenticating, location updating, and call routing for a roaming subscriber.

MSC service area. The geographical area controlled by a single MSC. Within a PLMN, there may be several MSC service areas.

MSC/VLR: Mobile Switching Center/Visitor Location Register. The MSC/VLR is a network component within the GSM mobile phone system.

MSISDN (Mobile Station ISDN). The number used to call a mobile subscriber. An MSISDN consists of a country code, a national destination code and a subscriber number.

MSRN (Mobile Station Routing Number). A temporary number that is allocated by the VLR and is used for routing a call for a mobile subscriber.

Multi-Path Fading. A loss of signal that occurs when a radio signal takes more than one path between the mobile station and the base transceiver station as a result of signal reflections off obstacles in the environment.

Multiplexer. A device that can combine and transmit several signals over a single line. The signals are then separated at the receiving end of the link. Time Division Multiple Access (TDMA) and Frequency Division Multiple Access (FDMA) both use multiplexing.

N-ISDN (Narrowband Integrated Services Digital Network). Services include basic rate interface (2B+D or BRI) and primary rate interface (30B+D - Europe and 23B+D - North America or PRI). It supports narrowband speeds at/or below 1.5 Mbps.

NADC (North American Digital Cellular standard). NADC is one of a number of second generation digital cellular standards used in North America. It is specified by the IS-54 standard. NADC offers three times the capacity of the original analog AMPS system.

Narrowband. A communications path that carries data at a speed of 56 kbps or less.

Narrowband network. A network capable of carrying data at a speed of 64 kpbs. The telephone network is a narrow band network.

Network. The connection between multiple infrastructure equipment sites for the reception and possible transmission of information.

Network architecture. The infrastructure equipment that makes up a network and the way it is arranged.

Network device. Any communications equipment attached to a network.

Network layer. The third layer of the OSI model which is concerned with the routing and switching of data from its source to its destination.

Network operator. A service provider for subscribers.

Network security. Software and hardware used on a network to restrict access to users of the network.

NMT (Nordic Mobile Telephony). An analog standard for mobile systems, which was developed by the Scandinavian Telecommunication Administrations.

NNI (Network Node Interface). An interface between ATM switches defined as the interface between two network nodes.

Node. A generic name for a single functional entity on a network, such as an MSC, BSC, HLR GMSC, VLR, or a BTS.

Nonvolatile. A term used to describe a device that retains its memory contents while it is powered off.

Nonwireline. Any cellular service provider other than the local PSTN.

NPA (Numbering Plan Area). Area codes for a country.

NPA routing. Numbering Plan Area routing. The routing of calls according to their area code.

Network And Switching Subsystem (NSS). A subsystem comprised of the MSC, GMSC, HLR, VLR, AuC, and EIR,

NTT (Nippon Telephone and Telegraph). The principal common carrier in Japan. The Japanese equivalent of AT&T in the U.S.

Octet. Eight (8) bits. Another term for a byte. However, a byte is not defined in all digital systems as 8 bits so the term 'octet' is used.

 

Offered traffic. The number of dialing attempts made to a subscriber within a specified time period.

Off-hook. A signal indicating that the telephone of the called party is engaged.

Off-line. A state used to identify that a device is not in operation.

OHG: Operators Harmonization Group. OHG is an industry body established to develop a single 3G cellular mobile standard.

ONAL (Off-network access line). A line connecting a telecommunications company network to the public network.

Off-network calling. Calling the public telephone system from within a private network.

OIW. A workshop for implementors of OSI. The North American regional forum at which OSI implementation agreements are decided.

On-hook. The status of telephone equipment that is ready to receive a call.

On-hook dialing. A method of dialing a telephone without the need to lift the receiver. The caller dials the number and uses the telephone speaker to listen to the status of the call. When the call is connected, the caller lifts the receiver and speaks.

On-network call. A call made within a private network.

One-way split. A facility that allows a telephone operator within a private exchange to speak to an extension without the caller hearing the conversation.

Online. The status of a device that is connected to another device and prepared to transmit or receive signals.

Online processing. The use of a computer/automated operator to operate equipment.

Open architecture. A network structure in which all hardware and software is based on industry standards in order to facilitate compatibility with as many other networks as possible.

Orbital period. The time that it takes a satellipe to complete one circumnavigation of its orbit.

Origin Server. A server on which a given resource is located or created. It is often referred to as a web or HTTP server.

OSI (Open System Interconnection). A standard for a layered architecture that allows data to be transferred among systems through networks. See layer.

OSS (Operation and Support System). An application program that allows a network operator to monitor, analyze and control the telecommunications network.

Packet. A specific number of bits of data sent over a link in a packet switched network. A packet contains the data and control information needed for the successful delivery of the packet to the desired address. The terms packet and frame are often used interchangeably.

Packet switching. A means for transmitting data messages by dividing the message into blocks or packets of standard length. Each packet has the destination address and other control information coded into it.

PAD (Packet Assembler and Dis-assembler). A PAD assembles packets of asynchronous data and sends these buffers in a burst to a packet-switched network. The PAD also disassembles packets from the network and sends the data to the non-packet device.

Paging. A one-way message that tells the subscriber that their attention is required.

Parity. A check for alterations in transmitted data.

Party. A participant in a call, for example, a called party (also known in telephony as the b-subscriber) and the calling party (also known in telephony as the a-subscriber).

Path loss. The attenuation of a radio signal, for example, as the mobile station moves away from the base transceiver station.

Payload. The part of an ATM cell that contains the information being sent.

PCS-1990. The U.S. variant of the European Global System for Mobile Communications (GSM) digital cellular standard that operates at 1900 MHz.

PCN . Personal Communciations Network. A wirless telephone system requiring low-power transceivers.

PCH (Paging Channel). The PCH is a special channel reserved within a cellular mobile phone network for paging or alerting mobile terminals to an incoming call.

PDA (Personal Digital Assistant).

PDC (Personal Digital Cellular). PDC is the second generation digital cellular standard developed for use in Japan.

PDC MAP: PDC Mobile Application Part. PDC MAP is the core network that supports the PDC standard.

PDH (Plesiochronous Digital Hierarchy). PDH (plesiochronous means nearly synchronous), was developed to carry digitized voice over twisted pair cabling more efficiently. This evolved into the North American, European, and Japanese Digital Hierarchies where only a discrete set of fixed rates is available, namely, nxDS0 (DS0 is a 64 kbps rate) and then the next levels in the respective multiplex hierarchies.

PDU (Protocol Data Unit). A PDU is a message of a given protocol comprising payload and protocol-specific control information, typically contained in a header. PDUs pass over the protocol interfaces which exist between the layers of protocols (per OSI model).

Physical layer. The first layer of the OSI model, which represents the hardware used for communication.

PIN (Personal Identification Number). A secret number that the subscriber enters in the mobile terminal to get access to the network.

PLMN Service Area. The geographical area served by a single network operator.

PN (Pseudo-Noise). A PN signal is a deterministic signal that has certain noise-like characteristics with regard to randomness and autocorrelation properties.

Polling. The transmission of a signal from the BTS to the mobile station to find out if the mobile station is still within the vicinity of the BTS.

Port. The point of entry to or exit from a network.

Port Identifier. The identifier assigned by a logical node to represent the point of attachment of a link to that node.

Powered off. The status of a mobile telephone that is not switched on.

PRBS (Pseudo-Random Binary Sequence). A PRBS is a binary PN signal (that is, a sequence of binary 1's and 0's that exhibits certain randomness and autocorrelation properties).

Presentation Layer. The sixth level of the OSI model, which is concerned with the presentation of data at the receiving end of the link.

Protocol. A guide to formal interactions. Protocols are agreed recommendations and standards that describe how systems communicate (inter-operate) with each other.

PSTN (Public Switched Telephone Network). The PSTN is the traditional fixed line telephone network.

PT (Payload Type). A 3-bit field in the ATM cell header that discriminates between a cell carrying management information or one which is carrying user information.

PVC (Permanent Virtual Circuit). A link with static route defined in advance, usually by manual setup.

PVCC (Permanent Virtual Channel Connection). An ATM connection where switching is performed on the VPI/VCI fields of each cell. A Permanent VCC is one which is provisioned through some network management function and remains indefinitely.

PVPC (Permanent Virtual Path Connection). An ATM connection where switching is performed on the VPI field only of each cell. A Permanent VPC is one which is provisioned through some network management function and remains indefinitely.

Q.921/931 ITU-TS (formerly CCITT). Q Series recommendations describing LAP-D, the Layer Two protocol for an ISDN D-channel.

Qbit (Qualifier bit). In X.25 networks, bit 8 in the packet header octet which is used to indicate if a packet contains control information.

QLLC (Qualified Logical Link Control). A datalink layer protocol defined by IBM to make SNA networks compatible with X.25 networks.

QoS (Quality of Service). In telecommunications - the idea that transmission rates, error rates, and other characteristics of the service can be improved upon and to some extent, guaranteed in advance.

QoS (Quality of Service) for ATM. Defined on an end-to-end basis in terms of the following attributes of the end-to-end ATM connection: Cell Loss Ratio, Cell Transfer Delay and Cell Delay Variation.

QPSK (Quadrature Phase Shift Keying). A system of modulating a satellite signal.

Queuing. Holding an incoming call until the resources become available to connect the call.

QD (Queuing Delay). The delay imposed on a cell due to the unavailability of resources to provide the connection the subscriber desires. This can be caused by congestion or the connection of a higher priority service using the available resources.

QUIPU. A database of electronic mail addresses, full names, and telephone numbers. This software allows someone to connect with X.500 directories around the world to find a particular e-mail address.

 

RACE: Research into Advanced Communications in Europe. RACE was a research programme promoted by the European Commission to promote research into advanced communications technologies.

Radio channel. A bandwidth broad enough to carry radio signals.

Radio communications. The use of radio waves for telecommunications.

Radio wave. An electromagnetic wave with a frequency between 100 MHz and 3,000,000 MHz.

RF (Radio Frequency). That part of the electromagnetic spectrum between the audio frequencies and high range frequencies - between 500 KHz and 300 GHz.

Rating. The system used to determine the customer charge for each call. Call charges are normally based on the time of day, the duration of the call, and any conditions specified in the contract between the subscriber and the carrier.

Rating engine. Receives the CDR (call data record) from the mediation device and applies appropriate rates to the each call, producing a 'rated CDR'. The rated CDR is then sent on to the accounting systems so the subscriber can be billed.

RCC (Radio Common Carrier). A communications carrier offering radio paging and cellular telephone services.

Real-time processing. The transmission or processing of data transactions as they occur, instead of waiting for a certain number of transactions to accumulate before they are processed (batch processing). The trend in telecommunications and many other industries is towards real-time processing.

Regeneration. The process of amplifying a digital signal when it has travelled a certain distance from its source in order to maintain signal clarity.

Regenerator. A device used for the process of regeneration.

Registration. Registration informs the network of the status of the MS, that is, whether the MS is attached (switched on) or detached (switched off). The status of the MS is registered through its IMSI being marked as ‘attached’ or ‘detached’ in the HLR.

Remittance. A transfer of funds for the purpose of paying a bill for example.

Reorder signal. A signal used to indicate to the caller that all required switching paths for the connection of a call are in use. The reorder signal repeats faster than the engaged tone.

RNC: Radio Network Controller. The RNC is a network component within the 3G IMT-2000 mobile communications system.

Roaming. A service provided by GSM that allows a subscriber to move between different cells.

Router. A physical device that is capable of forwarding packets based on network layer information and that also participates in running one or more network layer routing protocols.

RTT: Radio Transmission Technology. RTT is the name given to the development of the air interface component of IMT-2000 by the ITU.

SAR (Segmentation and Reassembly). A method of breaking up arbitrarily sized packets.

Satellite communications. The use of satellites to transmit radio signals around the globe.

SCH (Synchronization Channel). The SCH is a special channel reserved within a cellular mobile phone network for synchronization purposes. The SCH is broadcast by the base station to enable the mobile terminals within its cell synchronize themselves with the network. This involves alignment in terms of the operating frequency and system time as well as other important system information such as system identification numbers.

Schematic. A diagram that illustrates the electronic components of a system.

Scrambling. The deliberate distortion of transmitted signals to make them unintelligible. Scrambled signals are descrambled by a device at the destination.

SDH (Synchronous Digital Hierarchy). The ITU-TS International standard for transmitting information over optical fiber.

SDMA (Space Division Multiple Access). SDMA is a multiple access technique based upon sharing the access to the network on a geographical basis whereby the service area is divided into non-overlapping cells containing low-power transmitters.

Seamless. A term used in telecommunications to describe the integration of a number of different networks used to switch a single call. This interconnection appears 'seamless' to any subscriber because it is not apparent to them when a call is being switched to another network.

Selective cells. Selective cells (also known as sectored cells) are used to restrict the transmitted signal within a particular area.

Sequencing. The sequential numbering of packets in a message so they can be reassembled in the correct order at the destination address.

Server. A device (or application) that provides services to its clients based on submitted requests. A server may either accept or reject a connection request from a client.

Service provisioning. Part of the customer care system of a network. Contains a database of each subscriber and the services subscribed to. Requests for registration, or alterations to existing services are forwarded to the service provisioning systems.

Session. The connection of two devices for communication.

Session layer. The fifth layer of the OSI model, which is concerned with establishing a connection between communication devices. This layer is also responsible for the termination of a conversation/session when the devices have finished communicating.

Service area. The geographic area served by a single carrier.

SGSN: Serving GPRS Support Node. The SGSN is a network component within the GPRS system.

Shadowing. An air transmission problem that occurs when obstacles are in the path of the radio signal and causes it to vary in strength as the mobile station is roaming in the network.

SID (System Identification Number). The SID is used during registration of the mobile station to allow it determine if it is operating in its home system or in a foreign system.

SIM (Subscriber Identity Module). A card that the mobile subscriber inserts into the mobile terminal. It contains a code that uniquely identifies an individual subscriber to the network. The SIM card allows the subscriber to use the GSM service regardless of the mobile terminal, that is, a subscriber can remove the SIM card from terminal A, insert it into terminal B, and use any services the SIM card allows on terminal B.

Simplex circuit. A transmission channel that carries signals in only one direction at a time.

SMG: Special Mobile Group. SMG is a committee within ETSI that oversees the development of mobile standards.

SMS (Short Messaging Service). A service that allows mobile subscribers to both send and receive alphanumeric messages up to 160 characters long.

SONET (Synchronous Optical Network. An ANSI standard for transmitting information over optical fiber. This standard is used or accepted in the United States and Canada and is a variation of the SDH international standard.

Spectrum. The complete range of electromagnetic waves.

Speed dial. A feature of both cellular and landline telephones that store frequently used telephone numbers which can be activated by pressing a key.

Spread spectrum. A method of transmitting a signal by spreading it over a wide frequency band. Used initially by the military, it is becoming increasingly popular in commercial telecommunications as a way of helping to secure the signal, because spreading it over a wide spectrum makes it difficult to intercept and difficult to jam.

Standby time. The amount of time a fully charged mobile terminal can be left on before its battery runs down.

Standing wave. A wave phenomenon resulting from interference.

Subscriber. A paying customer to a network, for example, the GSM network.

Supplementary service. A supplementary service is an additional, optional service to which a user can subscribe usually for a fee. Examples of supplementary services include call forwarding, call waiting, calling line identification presentation.

SVC (Switched Virtual Circuit). A connection established via signaling. The user defines the endpoints when the call is initiated.

SVCC (Switched Virtual Channel Connection). A Switched Virtual Path Connection is one which is established and taken down dynamically through control signaling. A Virtual Channel Connection (VCC) is an ATM connection where switching is performed on the VPI/VCIfields of each cell.

SVPC (Switched Virtual Path Connection). A Switched Virtual Path Connection is one which is established and taken down dynamically through control signaling. A Virtual Path Connection (VPC) is an ATM connection where switching is performed on the VPI field only of each cell.

SWIFT (Society for Worldwide Interbank Financial Telecommunications). The communications network connecting most of the world's banks and financial institutions.

T-1DM T1 digital multiplexing. The multiplexing of 23 channels of 64 kbps each into a single 1.544 Mbps signal, and using the 24th channel to carry header information.

T-1. A T-carrier composed of 23 voice channels which can each carry 64 kbps. The 24 channels are aggregated to form a single channel having the capacity to carry 1.5 Mbps. The T-1 system is the standard for the regular local telephone service.

T-2. A T-carrier with four times the capacity of the T-1 carrier. T-2 has a can carry 6.312 Mbps (equivalent to 96 voice conversations).

T-3. A T-carrier with 28 times the capacity of the T-1 carrier. The T-3 carrier can carry 44.736 Mbps (equivalent to 672 voice conversations).

T-4. A T-Carrier with 168 times the capacity of the T-1 carrier. The T-4 carrier can carry 274.176 Mbps (equivalent to 4032 voice conversations).

TACS (Total Access Communications System). An analogue standard for mobile systems.

Tariff. A document that outlines the agreement between regulating agencies and service providers for rates for services or goods within a given area.

T-carrier. The AT&T hierarchy of digital systems that carry signals in digital format. The T-carriers are designated T-1, T-2 and T-4.

TCH (Traffic Channel). The TCH carries the user's telephone conversations. In the case of a digital cellular network, it carries digitized samples of the telephone conversations.

TCP (Transmission Control Protocol).

TDMA (Time Division Multiple Access). A technology used in digital cellular telephone communication to divide each cellular channel into a number of time slots in order to increase the amount of data that can be carried. This technology is called multiplexing. TDMA is used by Digital-American Mobile Phone Service (D-AMPS), Global System for Mobile communications (GSM), and Personal Digital Cellular (PDC). TDMA is implemented within each of these systems differently. An alternative multiplexing scheme to TDMA is code division multiple access (CDMA), which takes the entire allocated frequency range for a given service and multiplexes information for all users across the spectrum range at the same time. The TDMA standard was first specified in Interim Standard 54 (IS-54). The U.S. uses IS-136 for TDMA for both the cellular (850 MHz) and PCS (1900 MHz) spectrums. TDMA is also used for Digital Enhanced Cordless Telecommunications (DECT).

TDD: Time Division Duplex. In a TDD system simultaneous transmission and reception of radio signal is possible. This allows the mobile phone user to talk and listen at the same time. The mode of communication is facilitated by having different time slots within a TDMA scheme whereby transmission and reception take place a different times so as to avoid interfering with one other

TD-SCDMA: Time Division Synchronous CDMA. TD-SCDMA is a variant of CDMA. It is the basis of the Chinese proposal for IMT-2000 standardization.

Telecommunications. The transmission of voice or data using telephones or any other media.

Telecommuting. Working outside the traditional workplace, usually at home using telecommunications to deliver completed work tasks to the employer. Factors affecting telecommuting include the availability of sufficient bandwidth and telecommunications infrastructure in a given area.

Teleservice. A teleservice provides subscribers with the ability to communicate with other subscribers. Teleservices include basic telecommunications services, for example, voice telephony, voice mail, and GSM specific services.

Terminal. A connecting point for equipment, power, or a signal, such as a mobile station or a computer terminal.

TIA (Telecommunications Industry Association). The TIA was formed in 1988 as a result of the merger of the US Telephone Suppliers Association and the information technology group of the EIA. The TIA and EIA collaborate closely in producing standards that must be approved by ANSI before becoming US standards.

TLS (Transport Layer Security). TLS is a protocol that provides data integrity and privacy on a communications link over the Internet. It allows client-server applications to communicate and is designed to prevent eavesdropping, message forgery and interference.

TMSI (Temporary Mobile Station Identity). TMSI is used for signaling between the MS and the MSC. TMSI is used instead of the IMSI for security reasons.

Toll ticket. The lowest level of call data description. Created by the MSC when a subscriber roams from one cell to another and a handover is initiated. Subscribers pay extra for the privilege of cell roaming. A new toll ticket is generated for each handover. The toll tickets are collated at the end of the call and the subscriber is billed accordingly.

Trailer. Protocol control information located at the end of a PDU.

Transceiver. A device consisting of a transmitter and a receiver that transmits and receives signals.

TS (Traffic Shaping). A mechanism that alters the traffic characteristics of a stream of cells on a connection to achieve better network efficiency, while meeting the quality of service (QoS) objectives, or to ensure conformance at a subsequent interface. Traffic shaping must maintain cell sequence integrity on a connection. Shaping modifies traffic characteristics of a cell flow with the consequence of increasing the mean Cell Transfer Delay.

TSS (Telecommunication Standards Sector). An international organization that defines standards for telecommunication devices.

TTC: Telecommunications Technology Committee. TTC is a Japanese telecommunications standards body.

UA User Agent. An OSI application process that creates, submits, and takes delivery of messages on the user's behalf in the X.400 message handling system.

UCS (Uplink Control System). Software used to support the secure delivery of digitally compressed services.

UDP (User Datagram Protocol). A protocol that offers a limited service when messages are exchanged between network nodes in a network that uses IP. UDP is an alternative to TCP.

Umbrella cells. Cells used to reduce the number of handovers required to service fast moving mobile subscribers. An umbrella cell is a large cell that is superimposed over a series of smaller cells. It uses a different frequency to avoid interfering with these cells. When the network detects a fast moving mobile (indicated by its large number of handover requests), it passes control of the call over to the umbrella cell.

UMTS (Universal Mobile Telecommunications System). Part of the International Telecommunications Union’s ’IMT-2000’ vision of a global family of ’third-generation’ (3G) mobile communications systems. UMTS will allow the broadband, packet-based transmission of text, digitized voice, video, and multimedia at data rates up to 2 Mbps. UMTS , is the planned standard for mobile use