Telecoms Glossary


Third generation mobile data technology with connection speeds similar to early ADSL fixed-line broadband. Launched in 2003.


Fourth generation LTE / LTE- A mobile network technology launched in 2012, now with widespread coverage and far higher data speeds than its predecessor along with lower latency. Supports voice calls with VoLTE resulting in enhanced call quality.


Fifth generation technology standard for broadband cellular networks, which cellular phone companies began deploying worldwide in 2019, and is the planned successor to the 4G networks which provide connectivity to most current cellphones

Access network

The part of the network that connects customers to the exchange, sometimes called the local loop or the last mile.


Asymmetric Digital Subscriber Line. Technology that allows a standard telephone line to carry digital broadband signals. Downstream is faster than upstream, hence the ‘asymmetric’ element of the name


First generation ADSL with a maximum downstream speed of 8 Mbps.


Second generation ADSL Technology with a maximum downstream speed of 12Mbps.


An enhancement to ADSL2, which by doubling the frequency range increases maximum downstream speed to 24Mbps.


When upload and download speeds are different. Upload is much slower than download in ADSL and FTTC broadband.


The middle part of the network that links your local exchange to the core network.


The maximum data throughput of a network connection. Measured in Mbps (megabits per second) or Kbps (kilobits per second). Just as a wider water pipe will deliver more water, more quickly, broader bandwidth delivers more data, more quickly.


Broadband Enabling Technology – BT’s way of enhancing copper wires so that they can deliver speeds of up to 2Mbps up to 12km from the exchange. BET is a Single-pair High-speed Digital Subscriber Line (SHDSL) technology, which is a cousin of the more familiar Symmetric DSL (SDSL, same speed both ways) service for businesses. SHDSL combines elements from ADSL to work using frequencies that are not as prone to deterioration over distance.


Broadband bonding is a way in which you can speed up an ADSL broadband connection beyond that which would normally be available in your area by combining multiple lines. While not commonly utilised in the UK it is a good option if fibre optic or cable broadband is not available, and has proven particularly popular with businesses. It also acts as a back up if one of the connections goes offline.


A high-speed, always-on data internet connection. Ofcom and the UK Government consider that a “decent” broadband connection for typical home broadband usage is one capable of delivering a download speed of at least 10 Mbps and an upload speed of at least 1 Mbps. 

Broadband speed

The maximum data transfer speed of a broadband connection expressed in Mbps (Megabits per second) or Kbps (kilobits per second).


A green box that you might see on a street corner in a town or city that connects telephone lines to the exchange. Also known as a primary connection point.


A generic term often used in relation to broadband to describe fibre-optic networks – even more generically; a length of conductor carrying any electrical connection between two points, regardless of specific purpose.

Cable broadband

Cable broadband connects your home to a fibre cabinet in your area. However, instead of using copper wires, cable broadband uses coaxial cables to connect to the cabinet, giving you a much faster internet connection than the traditional copper phone line cables used for ‘superfast’ broadband connections (up to 60Mbps).So while cable broadband isn’t quite as fast as a full fibre connection, it is significantly faster than ‘fibre to the cabinet’ (FTTC) broadband.


Limiting a broadband connection – either in terms of line speed or data allowance.

Coax (coaxial) cable

Coaxial cable consists of a copper wire surrounded by a concentric conducting shield, separated by an insulating material. Also known as coax cable, this type of cable is ideal for carrying high frequency electrical signals with low losses. They are easy to install, affordable and very durable, making them an efficient middle ground between copper wires and fibre-optic cables.


Multiple users sharing the same available bandwidth.

Contention Ratio

The ratio of users sharing the same bandwidth – for example, a common contention ratio used with ADSL domestic broadband is 50:1 where 50 users would be vying for a share of the total available bandwidth.

Core network

The backbone of the communications network, carrying voice and data services around the country.

Dark fibre

Fibre optic cable which has been laid, but isn’t yet being used. Also called unlit fibre.

Data transfer rate

The speed at which data can be moved across a connection. Broadband services are measured in kilobits per second (Kbps), megabits per second (Mbps) or if you’re really lucky, gigabits per second (Gbps).

Dial-up internet

Internet access using a modem which dials the ISP over regular telephone lines. Until broadband became widely available in the early ’00s this was the way most of us got online. By modern standards, it’s very slow, but it is still used around the world in areas where broadband is not available.

Digital Poverty

Lacking the technology to get the best out of internet services. People in areas of digital poverty cannot, for example: fill in important forms and registrations, shop online, download videos and music, see and speak to other people on the internet, run their business, or engage in social media.

Digital Hub

A box installed in a central place within the community, also called a digital parish pump or community broadband hub. Fibre optic cable comes into the box, then broadband is distributed to local homes and businesses by various means. The fibre is known as a fat pipe, because whatever is needed in the future can come down it, from a megabit to 10 gigabits.


Data Over Cable Service Interface Specification: the international standards for sending data over a cable network. This is the standard that Virgin Media use.


DOCSIS 3.1 technology enables a new generation of cable services and helps operators continue to meet consumer demand for high-speed connections and sophisticated applications, positioning them to be the providers of choice in their markets. DOCSIS 3.1 supports blazing speeds of up to 10 gigabits per second, a speed only remotely possible with a fiber optic connection up until this point.


In terms of mobile broadband, ‘dongle’ is the word that has been almost universally adopted to describe the small device that receives a mobile broadband signal. These devices contain a SIM card from your mobile broadband supplier. You can get USB dongles that plug into a spare port on a computer, or mobile Wi-Fi (sometimes ‘MiFi’) dongles that broadcast a wireless signal.


Receive data from a source – typically used to describe the process of saving files from the internet, although it can be applied to any downstream data transfer.

Download Speed

The speed at which data flows towards the client from the source. Often used as a maximum possible rate for a given connection.


Domain Name System – essentially a constantly updated phone book that allows devices to convert human-readable URLs (domain names, web addresses) to machine-readable IP addresses and then use that data to locate the target on the internet and display that content to the user. When a DNS failure occurs, a device would find it impossible to locate a given resource such as a web site on the internet.


Distribution point – the point near to a premises where the main cable from a PCP is split to provide service at one or more localised premises. A DP can be at the top of a telegraph pole (Overhead DP), under a walkway (Underground DP) or on the side of a building.


Digital Subscriber Line – an umbrella term for any ADSL, SDSL, VDSL etc broadband connection.


The direction of flow of data towards the user.


Existing underground pipes that hold copper or fibre cables.


Enhanced Data Rates for GSM Evolution. An upgraded 2G mobile standard offering faster data transfer speeds. Still used by some UK networks. You may fall back on this if 3G or 4G isn’t available – on smartphones, it will usually be indicated by an ‘E’ next to the signal meter.


A technology that allows computers on a network to talk to each other.


A building where all of the copper phone lines are aggregated and where calls and data are routed to the provider’s backbone.

Fair Use Policy

A common type of ‘small print’ employed by service providers to protect themselves from users who abuse their systems or consume excessive amounts of data. These are typically used alongside ‘unlimited broadband’ packages to allow the provider to take action against anyone who they deem to be unfairly using their network. This may result in capping, traffic management or service termination.

Fat pipes

Bundles of fibre optic cable laid underground, underwater, or overhead.


A femtocell is a wireless access point that provides improved localised mobile coverage by using a home broadband connection to boost the mobile signal. This technology isn’t widely accepted but has obvious positive implications for improving mobile broadband signals in all kinds of environments.


Optical fibres are thin, flexible, hair-sized fibres that transmit data in the form of light signals. They can be bundled together, often encased in cable similar to an ordinary computer cable, and can transmit data millions of times faster and more reliably than metal wires.

Fibre optic broadband: A method of transferring data which utilises pulses of light sent across plastic or glass cables. Fibre optic data communications are fast and less prone to interference and have revolutionised telecommunications. It will one day entirely replace all the older copper cable that has been used on UK telephone lines for years. The old telephone network wasn’t introduced with data in mind and, as anyone living far away from their BT exchange will testify, a long copper wire from the exchange to the home can hamper broadband speeds. However, the UK is slowly turning to fibre optic. Both Virgin (through its cable service) and the Openreach network now offer much faster speeds thanks to fibre, though not all homes are covered. Speeds also vary depending on whether the fibre connection goes all the way to the home or only to your street cabinet.

Fixed line: Fixed-line broadband is a term used to describe internet delivered over a physical link, such as fibre or ADSL. The term is mostly used to differentiate fixed-line broadband from wireless services like mobile broadband and satellite internet.


Bringing fibre as close as possible to the property and then completing the connection with wireless.


Fiber to the building is a type of fiber-optic cable installation where the fiber cable goes to a point on a shared property and the other cabling provides the connection to single homes, offices or other spaces.


Fibre to the Cabinet – afibre network which runs all the way from the provider to a central location near the end user. This is typically in the form of an on-street communications cabinet. The connection from the cabinet to the end user is then either a plain old copper telephone line or a more modern coaxial copper cable. The vast majority of the fibre broadband available in the UK is FTTC.


Fibre to the Home – a fibre network which runs all the way from the provider to the end user. Capable of extreme speeds and reliability levels.


Fiber to the node is one of several options for providing cable telecommunications services to multiple destinations. Fiber to the node helps to provide broadband connection and other data services through a common network box, which is often called a node. Fiber to the node may also be called fiber to the neighborhood.


Fibre to the Premises


Fiber to the x or fiber in the loop is a generic term for any broadband network architecture using optical fiber to provide all or part of the local loop used for last mile telecommunications. is one of the latest ultrafast broadband technologies that can deliver over 100Mb/s (megabits per second) over very short twisted copper lines (or BT/Openreach telephones lines to you and I). It uses the same lines which currently supply fibre optic broadband up to 76Mb, with the higher speed achieved by expanding the frequency range. But it only functions over relatively short distances so will be limited to properties which lie no more than 500m from an exchange.

Gigabit broadband

Broadband service offering speeds of 1Gb or more. A gigabit connection is very fast – at a rate of 1Gb it would theoretically take just 32 seconds to transfer a 4GB DVD. Most home broadband connections in the UK cannot support gigabit yet but there are a few areas where FTTH networks have made it possible.

Gigabyte (GB)

1,000,000,000 bytes.

Headline Speed

The ‘up to’ speed used in marketing for a given connection. This often differs from the actual speed – sometimes significantly.


Hybrid Fibre Coaxial – the network technology used by Virgin Media. This is similar to FTTC in that a fibre optic cable runs to street cabinets, but the final connection into homes is achieved with a coaxial cable instead of the copper telephone line.


A place that has fast reliable broadband all the time. Sometimes also used as a term for a wifi connection in a community or cybercafe, for example Starbucks has a wifi hotspots.


High Speed Downlink Packet Access – mobile network standard offering faster 3G download speeds.


High Speed Packet Access – a family of mobile network protocols which includes HSDPA and HSUPA (High Speed Uplink Packet Access). The latest standard is Evolved HSPA, or HSPA+, which has a theoretical top speed of 337Mb. HSPA is available on all UK networks, and may be indicated by a ‘H’ on your device.


Internet Message Access Protocol – an email protocol. Many webmail providers support IMAP to allow users to download their email to client software. IMAP is recommended for users who access their email from multiple devices as it synchronises via the email server.

IP Address

A machine readable address format used by devices to locate resources on a network. Both IPv4 and IPv6 addresses are in common use.


Internet Protocol Television – the transmission or streaming of television programmes over Internet Protocol.


Integrated Services Digital Network – a standard for the transfer of voice and data over the telephone network typically used by larger organisations on the voice side.  On the data side, it was used to provide ‘high speed’ internet access before ADSL was available – by combining (or ‘bonding’) 2 64k ISDN channels, it was possible to achieve 128Kbps


Internet Service Provider – a company proving internet connectivity.


Latency or ‘lag’ variation. Can be used as a measure of stability for a given connection.


Kilobits per second, a measure of the rate of data transfer. 1,000 Kbps = 1Mbps.


A conventional telephone line connected by a fixed cable.


Local Area Network – a network covering a limited area, such as an office or home. Most LANs use either Wi-Fi or network cables.

Last-mile solution

How broadband from the digital village pump reaches your property (see access network). It will not be the same for everyone – it could be overhead cable, underground fibre optic cable or wireless. We like to call it the first mile because we believe the network starts with the customer, not the supplier. The last mile is a figure of speech, not a specific distance.


The time taken for one packet of data to travel from the user to a given server and back again. This is expressed in milliseconds and is sometimes referred to as ‘lag’ and the value often referred to as ‘ping’ or ‘ping time’.

Leased Line

A permanent, dedicated communications connection between two points.


Local Access (or Area) Network – computer network that connects computers and devices in a limited geographical area such as home, school, computer laboratory or office building. The defining characteristics of LANs, in contrast to wide area networks (WANs), include their usually higher data-transfer rates, smaller geographic area, and lack of a need for leased telecommunication lines.


Local loop unbundling is the process by which BT makes the access network (also known as the local loop) available to rent to other internet service providers so that they can run their service to customers. The competitor installs their own equipment in BT’s exchanges and establish a backhaul connection between the equipment and its core network.


Long Term Evolution is a next-generation 4G mobile data standard. While there has been some confusion over whether LTE counts as 4G or is simply a faster type of 3G, it has been widely adopted and marketed as such by networks across the world, including in the UK where it is used by the mobile networks for their 4G services.


Media Access Control Address – unique identifier assigned to a network device. Usually assigned at production and often unchangeable.


Masts are powerful radio transmitters and receivers which allow mobile phones and computers to connect to the internet or mobile phone networks.

Maximum Speed

The highest possible speed deliverable over a given connection.


Megabits Per Secondused to indicate the amount of data transferred per second, or the ‘bit-rate’. 1Mbps = 1000 Kbps.


Commonly 1 million bits, although technically actually 1,048,576 bits.


Commonly 1 million bytes, although technically actually 1,048,576 bytes.


A long-distance wireless link, with antennae usually sited on chimneys or masts.

Mobile broadband

This is broadband through your mobile phone or a dongle (a device that plugs into your computer) or mifi (your mobile phone or computer connects to it through wireless).

Modem (actually MODEM, from MOdulate, DEModulate)

A device that carries out modulation and demodulation – essentially an analogue to digital / digital to analogue converter that allows digital devices to converse over analogue telephone lines.

Modem Sync Speed

The speed at which the line speed is negotiated between the ISP and the MODEM depending on line conditions.


Mobile Virtual Network Operator. An MVNO is a mobile service which does not operate its own infrastructure but leases it from a network operator and resells access under its own brand. Examples of MVNOs include Virgin Mobile, Giffgaff, Tesco, and Sky Mobile.  MVNOs are often good value for money and may have unique features such as flexible contracts, cheap international calls, or services catering to specialist requirements which aren’t served by the major network operators.


Two or more computers connected together to enable the sharing of data.


The Office of Communications. Ofcom is the communications regulator. It regulates TV, radio, telecoms, mobiles and spectrum.


The company which maintains the former British Telecom network used for a majority of broadband and phone services. If a repair or installation is required it is Openreach, rather than your ISP, who will send an engineer. BT Openreach was formed in 2006 to allow competing providers access to the BT lines. In 2017 Openreach was further separated from BT – Openreach Ltd took legal ownership of staff and non-network assets, while BT continues to own the network, and parent company BT Group is the owner of Openreach Ltd.


In networking terms, a packet is a small amount of data sent over a network connection. Packets are a way of reliably communicating across a network – instead of sending very large amounts of data in one go, files are broken into small pieces (each a maximum of 64KB when sending over the internet) so if a packet is lost only the missing piece needs to be resent.

Packet Loss

Packet loss occurs when data packets sent over a network do not reach their destination. This is not a big problem for web browsing, but packet loss is an issue for anything that requires real-time communication. Packet loss during a Skype call can cause the audio to cut out or degrade the sound quality, and for online gaming, it can result in choppy gameplay similar to high latency.


Phishing is the act of luring unsuspecting internet users into providing personal information or installing malware. Typically this is achieved with the use of fake emails which contain links to clones of real web sites.


Post Office Protocol 3. A commonly used email protocol. Many webmail services allow access via POP3 so users can utilise email clients as well as the web interface. POP3 is best for accessing email from a single system as it deletes mail from the server after downloading, making it unwieldy to synchronise activity across multiple devices.

Related: IMAP


The practice of downloading and distributing copyrighted works such as movies, music, TV shows, books, and games.


A router directs traffic on a network. In relation to broadband, the router usually (but not always) includes a modem so is responsible for connecting to the internet as well as providing networking in your home. A broadband router may also be called a hub.

Satellite broadband

Broadband service provided by a satellite. In order to use this you need a dish connected to a modem. The equipment is expensive compared to regular home broadband but has a big plus: it doesn’t need any fixed lines and will work anywhere within the footprint of the satellite, making it ideal for fast connectivity in remote locations where other services aren’t available.


Symmetrical Digital Subscriber Line – similar to ADSL, however both downstream and upstream speeds are the same. The connection operates with the same maximum upload and download speeds.


Any program or device that responds to requests to provide data to a client. This can be on a local network or more commonly over the internet. Servers are typically assigned a specific task, such as web server, mail server etc – in practice one machine often fulfils multiple server roles.


Making use of data while it is still in transit – as opposed to downloading and then using a completed file. Data is transferred to the client application and as long as the downstream speed is sufficient, it can be used without having to wait for a download to complete.


According to the EU, ‘superfast’ broadband is any connection with a speed of 30Mb+ according to Ofcom. In the UK this rules out any service running on old BT telephone lines (ADSL) or any mobile broadband up to and including 3G. Our options for superfast home broadband include fibre optic and cable broadband, satellite internet and possibly 4G.

Symmetrical broadband

An internet connection which has the same download and upload speed.


This term refers to internet service providers deliberately slowing internet connections. It is most commonly employed during peak broadband usage times, and against customers deemed to have overstepped their usage cap or fair usage policy.


Network or data traffic is a term for data being sent across a network.

Traffic management

The practice of controlling and managing data traffic across a network. Traffic management, or traffic shaping, can be benign and simply intended to improve performance for the majority of users. For example it may be implemented to prioritise bandwidth-heavy video streaming during busy periods. But aggressive traffic management used to throttle connections can cause a severe drop in performance for certain activities, particularly file sharing. While some ISPs no longer routinely use traffic management it is still in place on many services, so check this before you buy.


Very high speed broadband, which Ofcom defines as any connection with a speed of 300Mb+. 


Broadband without limits, where you can use it as much as you like without additional charges or restrictions. There’s been a great deal of controversy over unlimited broadband in the past as providers liked to sneak Fair Use Policies (FUP) in the small print or come up with their own loose definition of the word, but today many ISPs are actually unlimited. Sometimes they may have no data usage caps but still utilise traffic management, while others are ‘truly unlimited’ and have no usage caps or traffic management policy.


To transfer data to a remote device. In the case of consumer broadband, to transfer data from the user’s device to another device, typically a server on the internet.

Upload Speed

The speed at which data flows from the client to the remote target device. Often used as a maximum possible transfer rate for a given connection.


Away from the user – the reverse of Downstream.


Uniform Resource Locator – a human-readable and easily-remembered web address


Very high speed digital subscriber line (VDSL) is a DSL technology that provides a faster data transfer rate than asymmetric digital subscriber line (ADSL) and ADSL2+ technologies. It sends out data in the 13 to 55 Mbps range over small distances, which are typically between 330 to 1650 yards of twisted pair copper wire. The shorter the distance, the higher the data transfer rate. VDSL enables users to upload, download and process data more rapidly.


An enhancement to VDSL designed to support the wide deployment of triple play services such as voice, video, data and high-definition television (HDTV) VDSL2 is intended to enable operators and carriers to gradually, flexibly, and cost-efficiently upgrade existing xDSL infrastructure.


Video On Demand – selecting and accessing video at a desired time as opposed to accessing broadcast television in line with a published schedule. Netflix, Amazon Prime and Now TV are examples of VOD.


Voice over Internet Protocol – any service allowing voice calls to be made over the internet instead of traditional telephone infrastructure. A voice-only Skype call would be an example of a VoIP call.


Wide Area Network. A network spread over a large geographic area, as opposed to a LAN. The internet is the largest WAN, but private WANs are used by companies, academic institutions and governments for internal communications.


Wireless Application Protocol. A standard for mobile data services, WAP was designed around the small screens and slow data connections of early mobile phones. It was hyped as a huge leap forward but the reality of using a WAP browser was less exciting than the marketing suggested. It gained some popularity but faded away once phones offered regular web access.


Wireless Fidelity – aform of network connectivity eliminating cables and instead using Ethernet protocols over radio signals.


Worldwide Interoperability for Microwave Access. A 4G broadband technology offering a wireless broadband alternative without the need for cables. WiMAX lost out to LTE in the race to be the next generation of mobile broadband, largely because the latter fits the established network model mobile companies already use; they simply had to upgrade their technology rather than starting afresh.


Wireless Local Area Network. A LAN that uses Wi-Fi to transfer data rather than physical network cables.