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ITU and its Activities Related to Internet Protocol (IP) Networks




3G: Third-generation mobile network or service. Generic name for mobile network/service based on the IMT-2000 family of global standards.

ADSL: Asymmetric digital subscriber line. A technology that enables high-speed data services to be delivered over twisted pair copper cable, typically with a download speed in excess of 256 kbit/s, but with a lower upload speed.  Corresponds to ITU Recommendation (standard) ITU-T G.992.1

ADSL2: Asymmetric Digital Subscriber Line 2, (ITU‑T G.992.3 and ITU‑T G.992.4). A sequel to the original ITU Recommendation.  It allows increased line speeds,  new power-saving elements, and extends the reach of the original ADSL specification.

ADSL2+: Asymmetric digital subscriber line 2 plus, (ITU-T G.992.5). This revised version of ADSL2 enables increased speeds by increasing the frequencies used on the copper line.

ATM: Asynchronous transfer mode. A transmission mode in which the information is organized into cells; it is asynchronous in the sense that the recurrence of cells from an individual user is not necessarily periodic.

Bandwidth: The range of frequencies available to be occupied by signals. In analogue systems it is measured in terms of Hertz (Hz) and in digital systems in bits per second (bit/s). The higher the bandwidth, the greater the amount of information that can be transmitted in a given time. High bandwidth channels are referred to as “broadband” which typically means 1.5-2.0 Mbit/s or higher.

Bit/s: Bits per second. Measurement of the transmission speed of units of data (bits) over a network. Also kbit/s: kilobits (1’000) per second; Mbit/s: megabits (1’000’000) per second, and Gbit/s: Gigabits (1’000’000’000) per second.

Broadband: Although there exist various definitions of broadband that have assigned a minimum data rate to the term, it may be defined as transmission capacity with sufficient bandwidth to permit combined provision of voice, data and video, with no lower limit. Effectively, broadband is implemented mainly through ADSL, cable modem or wireless LAN (WLAN) services.

Browser: Application that retrieves WWW documents specified by URLs from an HTTP server on the Internet. Displays the retrieved documents according to the Hyptertext Markup Language (HTML).

Cable modem: A technology that allows high-speed interactive services, including Internet access, to be delivered over a cable TV network.

CDMA: Code division multiple access. A technology for digital transmission of radio signals based on spread spectrum techniques where each voice or data call uses the whole radio band and is assigned a unique code.

CDMA2000: Code division multiple access 2000. A third-generation digital cellular standard based on Qualcomm technology. Includes CDMA2000 1x, 1xEV-DO (Evolution, Data Optimized) and 1xEV‑DV (Evolution, Data and Voice). One of the IMT‑2000 “family” of standards.

Cellular: A mobile telephone service provided by a network of base stations, each of which covers one geographic cell within the total cellular system service area.

Channel: One of a number of discrete frequency ranges utilized by a base station to transmit and receive information from cellular terminals (such as mobile handsets).

Circuit-switched connection: A temporary connection that is established on request between two or more stations in order to allow the exclusive use of that connection until it is released. At present, most voice networks are based on circuit-switching, whereas the Internet is packet-based.  See also Packet-based.

Connectivity: The capability to provide, to end-users, connections to the Internet or other communication networks.

Digital: Representation of voice or other information using digits 0 and 1. The digits are transmitted as a series of pulses. Digital networks allow for higher capacity, greater functionality and improved quality.

DNS: Domain Name System. The Domain Name System is a distributed hierarchical lookup service.  It is primarily used on the Internet and other IP-based networks to translate between domain names and Internet Protocol (IP) addresses. 

DOCSIS: Data over cable systems interface specifications, (ITU-T J.112). ITU-T Recommendation J.112 for cable modems, originally based on technologies developed by Cablelabs.  It specifies modulation schemes and the protocol for exchanging bi-directional signals over cable.

DOCSIS2: Data over cable systems interface specifications 2, (ITU-T J.122). ITU-T Recommendation J.122, approved at the end of 2002, is based on a revised version of DOCSIS, originally based on technologies developed by Cablelabs.

DSL: Digital subscriber line. See also ADSL, ADSL2, ADSL2+, SHDSL, SDSL, VDSL and xDSL.

DSLAM: Digital subscriber line access multiplexer. A device, located at the central office of a DSL provider, that separates and routes the voice-frequency signals and data traffic on a DSL line.

E-commerce: Electronic commerce. Term used to describe transactions that take place online where the buyer and seller are remote from each other.

E-mail: Electronic mail. A method of electronically passing messages from one computer user to another, typically over computer networks.

End-user: The individual or organization that originates or is the final recipient of information carried over a network (i.e. the consumer).

ENUM: Electronic Numbering. A protocol that is the result of work of the IETF's Telephone Number Mapping working group that provides facilities to resolve ITU-T E.164 telephone numbers into other resources or services on the Internet through a lookup service using the Domain Name System (DNS).

Ethernet: A protocol for interconnecting computers and peripheral devices at high speed. Ethernet can run on several types of wiring including: twisted pair, coaxial, and even fibre optic cable. Ethernet was invented at the Xerox Palo Alto Research Center in the 1970s by Dr. Robert M. Metcalfe. Formal specifications for Ethernet were published in 1980 by a multi-vendor consortium that created the DEC-Intel-Xerox (DIX) standard. This technology was later adopted for standardization by the LAN standards committee of the Institute of Electrical and Electronics Engineers (IEEE 802) and the International Organization for Standardization (ISO). The standard is periodically updated including 100-Mbps Fast Ethernet and 10 Gigabit Ethernet.

FDMA: Frequency division multiple access. A cellular technology that has been used in the first-generation analogue systems (i.e. NMT, AMPS, and TACS).

FTTH: Fibre to the home. A high-speed fibre optic, Internet connection that terminates at a residence. See FTTx.

FTTx: Fibre to the x, where x is a home (FTTH), building (FTTB), curb (FTTC), or neighbourhood (FTTN). These terms are used to describe the reach of an optical fibre network. 

Fixed line: A physical line connecting the subscriber to the telephone exchange. Typically, fixed-line network is used to refer to the PSTN (see below) to distinguish it from mobile networks.

Frequency: The rate at which an electrical current alternates, usually measured in Hertz (see Hz). It is also used to refer to a location on the radio frequency spectrum, such as 800, 900 or 1’800 Mhz.

GMPLS: Generalized Multiprotocol Label Switching. An extension of the existing MPLS that supports TDM, wavelength and spatial switching. One of the main architectural enhancements proposed by GMPLS is the complete separation of the control and data planes of various networking layers.

Hotspot: An access point to a wireless local area network (WLAN).  Hotspots are areas where wireless data can be sent and received, and Internet access is provided to wireless devices.  For example, a laptop computer can be used to access the Internet in a hotspot provided in an airport or hotel.

Hz: Hertz. The frequency measurement unit equal to one cycle per second.

IMT-2000: International Mobile Telecommunications-2000. Third-generation (3G) “family” of mobile cellular standards approved by ITU. For more information see the website at:

Incumbent: The major network provider in a particular country, often a former State-owned monopoly.

Internet: Global network of interconnected networks that use the Internet protocol (see IP).

Internet backbone: The collection of main network connections and telecommunications lines comprising the Internet.

IETF: Internet Engineering Task Force. Large open international community of network designers, operators, vendors, and researchers concerned with the evolution of the Internet architecture and the smooth operation of the Internet open to any interested individual.

IP: Internet protocol. The dominant network layer protocol used with the TCP/IP protocol suite. The IP protocol suite is maintained by the IETF.

IP telephony: Internet protocol telephony. IP telephony is used as a generic term for the conveyance of voice, fax and related services, partially or wholly over packet-based, IP-based networks. See also VoIP and Voice over broadband.

ISDN: Integrated services digital network. A digital switched network, supporting transmission of voice, data and images over conventional telephone lines.

ITU: International Telecommunication Union. The United Nations specialized agency for telecommunications. See

ITU-D: Telecommunication Development Sector. One of three Sectors of the International Telecommunication Union (ITU).

ITU-R: Radiocommunication Sector. One of three Sectors of the International Telecommunication Union (ITU).

ITU-T: Telecommunication Standardization Sector. One of three Sectors of the International Telecommunication Union (ITU).

LAN: Local area network. A computer network that spans a relatively small area. Most LANs are confined to a single building or group of buildings. However, one LAN can be connected to other LANs over any distance via telephone lines and radio waves. A system of LANs connected in this way is called a wide-area network (WAN). See also WLAN.

LLU: Local loop unbundling. The process of requiring incumbent operators to open the last mile of their legacy networks to competitors.  Similar reference to ULL (unbundled local loop). 

Local loop: The system used to connect the subscriber to the nearest switch. It generally consists of a pair of copper wires, but may also employ fibre-optic or wireless technologies.

Main telephone line: Telephone line connecting a subscriber to the telephone exchange equipment. This term is synonymous with the term fixed line used in this report.

Mobile: As used in this report, the term refers to mobile cellular systems and to mobile phones.

MPLS: Multi-Protocol Label Switching. An IETF–defined protocol originally based on Cisco tag switching technology that is used in IP traffic management. Basically, it provides a means for one router to pass on its routing priorities to another router by means of a label and without having to examine the packet and its header, thus saving the time required for the latter device to look up the address for the next node. It can also facilitate Quality of Service (QoS) provisioning.

OFDMOrthogonal frequency division multiplexing. A method of digital modulation in which a signal is split into several narrowband channels at different frequencies in order to minimize interference among channels that are close in frequency. OFDM is used in European digital audio broadcast services, and also in wireless LANs.

Packet: Block or grouping of data that is treated as a single unit within a communication network.

Packet-based: Message-delivery technique in which packets are relayed through stations in a network. See also Circuit-switched connection.

Penetration: A measurement of access to telecommunications, normally calculated by dividing the number of subscribers to a particular service by the population and multiplying by 100. Also referred to as teledensity (for fixed-line networks) or mobile density (for cellular ones), or total teledensity (fixed and mobile combined).

Pervasive computing: A concept which describes a situation in which computing capability is embedded into numerous different devices around the home or office (e.g. fridges, washing machines, cars, etc.). Also referred to as ubiquitous computing. Pervasive communications implies that the microchips in these devices are also able to communicate, for instance their location and status.

Protocol: A set of formal rules and specifications describing how to transmit data, especially across a network.

PSTN: Public switched telephone network. The public telephone network that delivers fixed telephone service.

QoS: Quality of service. A measure of network performance that reflects the quality and reliability of a connection. QoS can indicate a data traffic policy that guarantees certain amounts of bandwidth at any given time, or can involve traffic shaping that assigns varying  bandwidth to different applications.

RFID: Radio frequency identification. A system of radio tagging that provides identification data for goods in order to make them traceable. Typically used by manufacturers to make goods such as clothing items traceable without having to read bar code data for individual items.

SDO: Standards Development Organization. An organization that develops standards.

Server:   (1) A host computer on a network that sends stored information in response to requests or queries.
(2) The term server is also used to refer to the software that makes the process of serving information possible. 

SDSL: Symmetrical DSL. A proprietary North American DSL standard. However, the term SDSL is often also used to describe SHDSL.

SHDSL: Single pair high-speed DSL. The informal name for ITU-T Recommendation G.991.2 that offers high-speed, symmetrical connectivity over a twisted copper pair.

SIP: Session initiation protocol. An IETF-specified standard (RFC 2543) used to initiate, manage, and terminate interactive sessions between one or more users on the Internet.

Spectrum: The radio frequency spectrum of hertzian waves used as a transmission medium for cellular radio, radiopaging, satellite communication, over-the-air broadcasting and other services.

TCP: Transmission control protocol. A transport layer protocol that offers connection-oriented, reliable stream services between two hosts. This is the primary transport protocol used by TCP/IP applications. The IP protocol suite is maintained by the IETF.

TDM: Time Division Multiplexing. A digital transmission method that combines signals from multiple sources on a common path. This common path is divided into a number of time slots and each signal or channel is assigned its own intermittent time slot, allowing the path to be shared by multiple channels.

Teledensity: Number of main telephone lines per 100 inhabitants. See Penetration.

Total teledensity: Sum of the number of fixed lines and mobile phone subscribers per 100 inhabitants. See Penetration.

Ubiquitous computing: A term that reflects the view that future communication networks will allow seamless access to data, regardless of where the user is.  See Pervasive computing.

ULL: Unbundled local loop. See LLU.

UMTS: Universal mobile telecommunications system. The European term for third-generation mobile cellular systems or IMT-2000 based on the W-CDMA standard. For more information see the UMTS Forum website at:

Universal access: Refers to reasonable telecommunication access for all. Includes universal service for those that can afford individual telephone service and widespread provision of public telephones within a reasonable distance of others.

USO: Universal service obligations. Requirements that governments place on operators to offer service in all areas, regardless of economic feasibility. 

VDSL: Very-high-data-rate digital subscriber line. (ITU-T G.993.1). The fastest version of DSL that can handle speeds up to 52 Mbit/s over very short distances. Often used to branch out from fibre connections inside apartment buildings.

VoIP: Voice over IP. A generic term used to describe the techniques used to carry voice traffic over IP (see also IP telephony and Voice over broadband).

VPN: Virtual private network. A method of encrypting a connection over the Internet. VPNs are used extensively in business to allow employees to access private networks at the office from remote locations. VPNs are especially useful for sending sensitive data.

W3C: World Wide Web Consortium. W3C was created in October 1994 to lead the World Wide Web to its full potential by developing common protocols that promote its evolution and ensure its interoperability. See

W-CDMA: Wideband code division multiple access.  A third-generation mobile standard under the IMT‑2000 banner, first deployed in Japan. Known as UMTS in Europe. See also CDMA.

WDM: Wave division multiplexing. Technology that allows multiple data streams to travel simultaneously over the same fibre optic cable by separating each stream into its own wavelength of light. 

Wi-Fi: Wireless fidelity. A mark of interoperability among devices adhering to the 802.11b specification for Wireless LANs from the Institute of Electrical and Electronics Engineers (IEEE). However, the term Wi‑Fi is sometimes mistakenly used as a generic term for wireless LAN.

WiMAX: Fixed wireless standard IEEE 802.16 that allows for long-range wireless communication at 70 Mbit/s over 50 kilometres. It can be used as a backbone Internet connection to rural areas.

Wireless: Generic term for mobile communication services which do not use fixed-line networks for direct access to the subscriber.

WLAN: Wireless local area network. Also known as Wireless LAN. A wireless network whereby a user can connect to a local area network (LAN) through a wireless (radio) connection, as an alternative to a wired local area network. The most popular standard for wireless LANs is the IEEE  802.11 series.

WLL: Wireless local loop. Typically a phone network that relies on wireless technologies to provide the last kilometre connection between the telecommunication central office and the end-user.

WSIS: The United Nations World Summit on the Information Society. The first phase of WSIS will take place in Geneva (hosted by the Government of Switzerland) from 10 to 12 December 2003. The second phase will take place in Tunis (hosted by the Government of Tunisia), from 16 to 18 November 2005. For more information see:

xDSL: While DSL stands for digital subscriber line, xDSL is the general representation for various types of digital subscriber line technology, such as ADSL, SHDSL, and VDSL. See ADSL, SHDSL, VDSL.



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Updated : 2011-04-04