Community Broadband Scotland

Community Broadband Scotland

Technical glossary

A downloadable PDF of this glossary is avaiable in the Related Documents on the left-hand side of this page.

Activation is the process by which your existing phone line becomes enabled to receive data over the internet and telephone calls simultaneously. The activation takes place at your local phone exchange. So, when you subscribe to a broadband package, your broadband service will not be in place until activation occurs.

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

Asymmetric Digital Subscriber Line (ADSL)
ADSL broadband uses BT landlines to provide broadband connection to properties in the UK.  This service is provided to every exchange in the country.  There are 3 current varieties: Exchange Activate, ADSL Max, ADSL 2+. 

ADSL Max can provide up to 8Mbps download speed.

Fastest version of ADSL, which provides up to 24Mbps download speeds and is being rolled out to many BT exchanges as part of their current network upgrade plans.

The high capacity link that connects a sub network (community) to the internet core network.  In most small communities connections will be aggregated at a single point, usually the local telephone exchange.

The maximum speed of data transfer across an internet connection.  Bandwidth is expressed in kbps or

Broadband Delivery UK - lead UK organisation, a team within the Department for Culture, Media and Sport.

BET (Broadband Enabling Technology) is 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. But it’s not cheap: it costs around £1000 per premises.

Bonded ADSL Lines
Bonded ADSL uses multiple ADSL lines ‘bonded’ together which combines the bandwidth in order to increase the overall speed. Basically two 8Mbps ADSL lines bonded together could effectively produce up to 16Mbps bandwidth.

A term used to describe internet that is always on, high speed, and significantly faster than earlier dial up technology.  Can be delivered through telephone, cable, wireless or satellite technology.  Access speeds are generally 512kbps or more.

Broadband Not Spot
A geographic post code area where customers do not have access to fixed line or wireless broadband.#

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.

Cable Broadband
Cable broadband uses the same fibre optic technology as cable TV (e.g. Virgin Media).  It provides high speed broadband, but is only available in communities that have cable service in the area – mostly urban areas with high population.

Cloud Computing
Location-independent computing, whereby shared servers provide resources, software and data to computers and other devices on demand.

This refers to the number of properties sharing a broadband connection.  The majority of broadband connections are contended, as it is unlikely that all users would be using their broadband at the same time.  Contention is expressed in ratios, for example 50:1 (a maximum number of 50 users access one connection). 

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

Dial Up
Dial up uses the telephone line to establish a connection to the internet.  Dial up can typically reach speeds of up to 56kbps.  In contrast to broadband, the telephone line cannot be used to make and receive calls whilst connected to the internet.

Existing underground pipes that hold copper or fibre cables.

Download Speed
The speed at which a user is able to download (transfer) data from the internet to their computer/device.

This is the process of translating data into a secret code for protection purposes. 

Exchange Activate
A cut down version of ADSL supplied to a small number of exchanges in Scotland, mostly in the Highlands and Islands. It is characterised by only providing 512kbps (0.5Mbps) download speeds and from a limited number of internet service providers (ISPs), usually only 3-4 depending on the exchange.

This is the front cover of the BT socket into your house. Removing it, and plugging your router directly into the engineer socket behind the faceplate can reduce interference on your line and often increase the speed and consistency of your broadband connection.

Fair Usage policy (also known as Acceptable Use policy)
Fair Usage policies are part of the contract that you sign up to when you subscribe to a particular package with an Internet Service Provider (ISP).  Fair Usage policies may restrict what you do online. For example, many state that you can’t send spam emails or use the internet connection for illegal purposes. Some also insist that you maintain adequate anti-virus systems on your PCs. If they determine that your PC is spreading a virus infection, they can switch off your connection immediately.

Fibre Optic
Fibre optic cable is flexible, thin glass pipes using waves of light.  It can deliver higher broadband speeds over longer distances without the loss seen in traditional metal (e.g. copper or aluminium) cabling.  

A firewall acts as a barrier against unauthorised access to your computer by hackers via the internet. All information to and from your computer to the internet has to pass through the firewall. Suspicious or unauthorised traffic that may present a risk is automatically filtered out.

Fibre to the Cabinet (FTTC) services are being rolled out by BT as their Next Generation Broadband platform. This replaces the existing copper connection between the exchange and the green street cabinet with fibre and installs VDSL (Very-High-Speed Digital Subscriber Line) equipment in an upgraded street cabinet into which the existing customer copper lines connect. This means there is a shorter length of copper between the customer and the high speed fibre network which means faster connections can be provided. Headline speeds from FTTC are 80Mbps download and near 20Mbps upload.

Fibre to the home (FTTH) or fibre to the premises (FTTP) – this is where fibre is laid directly to the property. 

IP Address
This stands for Internet Protocol address, and is the unique internet address of your computer, similar to your postcode. IP addresses are numeric, e.g. You may have noticed them appear occasionally in the bottom bar of your web browser.

Integrated Services Digital Network:  An Internet service that is faster than dial-up but slower than broadband, with speeds around 128 Kbps. You need two telephone lines to use this service

An internet service provider (ISP) is a company that provides a broadband service. 

Kbps stands for kilobits per second, and is a measure of the speed of data transfer (1 kilobit per second = 1000 bits per second)

LAN (Local Area Network)
A LAN is a network of connected computers. This may be by cabling or via a wireless connection. A LAN is often used by businesses, where the computers can use the same internet connection. Many homes now have a LAN too – this lets several PCs and laptops share the same broadband connection and perhaps other devices such as printers.

The time delay caused by the distance a broadband signal has to travel.  High-latency is encountered with satellite broadband, caused by the long distances (up to a satellite and back) that the broadband signal has to travel. This can limit the use of many real-time applications (e.g. Voice over IP (VoIP), video conferencing and online gaming).

Leased Line (Internet)
Internet leased line is a premium internet connectivity product, delivered over fibre normally, which is dedicated and provides uncontended, symmetrical speeds.  It is also known as an ethernet leased line, DIA line, data circuit or private circuit.

Local Loop Unbundling
Local Loop Unbundling is where an alternative provider to BT (for example Talk Talk or Sky, etc.) install equipment into the local exchange and provide their own ADSL services. There are a relatively small number of these in Scotland due to the economics of supply and demand.

Load Balancing
ADSL load balancing is where two or more ADSL connections are connected and the ISP balances the internet traffic and activity over the two lines. This increases the resilience of the network as it is not reliant on only 1 ADSL connection. Load-balancing attempts to route Internet traffic optimally across two or more ADSL connections to deliver a better experience to broadband users simultaneously accessing Internet application.

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

Mb (megabyte)
A megabyte is a unit for measuring the amount of storage space digital information takes up. 

Mbps stands for megabits per second, and is a measure of the speed of data transfer (1 megabit per second = 1000 kilobits per second)

Microfilter/Line Splitter
A small box that plugs into your phone socket and ‘splits’ your line into two bands – one for telephone and another for broadband use.  A splitter helps to reduce interference on the line when you use broadband and the phone at the same time.

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

Migration Fee
This is fee that you would pay to move from your existing provider to a different one.

Mobile Broadband
Broadband delivered by mobile carriers (e.g. O2, Vodafone, etc) to portable devices (such as mobiles, tablets etc.).

Mobile Not Spot
Areas where there is no mobile coverage

Modem (Modulator/Demodulator)
A device that allows computers to send and receive data using telephone lines, a modem maybe required to connect to the Internet.

Next Generation Broadband
Next Generation Broadband (NGB) is high speed broadband that exceeds the capabilities of copper-based broadband infrastructure.  Speeds vary depending on the technology used (satellite, fibre, wireless etc).   The European Commission’s Digital Agenda sets 30Mbps as a minimum target for NGB speeds.  Scottish Government, under their Step Change programme, want to see significant uplift in speeds, with 85-90% of premises getting 40-80Mbps by the end of the 3 year programme. 

Office of Communications – the UK’s independent telecommunications regulator and competition authority. 

A router sits between your computer and the modem connecting you to the internet. They are normally used when more than one computer or other device is sharing a broadband connection. They “route” the information received from the internet to the right computer or device.

SLA (Service Level Agreement)
A Service Level Agreement details the terms and conditions for the service provided by your ISP. This will be part of your subscription contract with them and will state what service they will provide – and what happens if they don’t.

Standard Broadband
BDUK has defined standard broadband as a service available at the edge of the network that allows a quality home working experience, for which a headline access speed of 2Mbps can be used as a proxy.

Superfast Broadband
BDUK has defined Superfast Broadband as having a potential headline download access speed of 30Mbps or above, and in no cases less than 24Mbps, with no upper limit. Typically, at a wholesale level, the underlying capability can be measured in gigabits. The retail market then takes this capability and delivers affordable propositions.

Satellite Broadband
Broadband services delivered through a satellite that communicates with a computer (or computers) through a satellite dish on the premises. 

State Aid
State Aid refers to forms of assistance from a public body, or publicly-funded body, given to selected undertakings (any entity which puts goods or services on the given market), which has the potential to distort competition and affect trade between member states of the European Union. The European Commission monitors and controls State Aid in the EU. Member States are obliged to notify and seek approval from the Commission before granting State Aid. This gives the Commission the opportunity to approve or refuse to approve the proposed measure.

Streaming refers to watching or listening to digital video or audio content online, without it being stored on your computer or device.

Symmetric digital subscriber line (SDSL)
Offers symmetrical broadband services over a telephone line (same download and upload speeds)

Where upload speeds are the same as download speeds. True Next Generation Access will be symmetric. Video conferencing requires symmetric upload and download speeds. Current broadband is asymmetric.

The average rate of successful message delivery over a communication channel.

Upload speed
The speed at which a user is able to upload (transfer) data from their computer/device to the internet.

Voice over Internet Protocol (VoIP)
VoIP is a technology that allows you to make telephone calls using your broadband internet connection instead of your analogue phone line. Your voice is broken up by special software into small packets of data, sent through the internet, and reassembled at the other end. This happens almost instantaneously, with no discernable time lag and at good quality – as good as a landline call.

VPN (Virtual Private Network)
A Virtual Private Network is a secure means to allow businesses to give remote access to their main office computer network. This might be to other branch offices or to people working at home or in other locations (e.g. sales staff on the road).

WAN (Wide Area Network)
A WAN is a geographically widespread network that might include many linked Local Area Networks (LANs) as well as individual PCs. A typical user of a WAN may be a business with several area offices in various locations.

A wayleave is a contractual agreement between a landowner and a utility provider which allows the provider to install plant and equipment on private land and have access rights to maintain and repair it.

White Space
Space on the licensed radio spectrum freed up by the switch from analogue to digital TV.

White area
An area where there is no broadband infrastructure and where no such infrastructure is likely to be developed in the near future (taken to mean three years).  These locations are eligible for public subsidy under EU state aid guidelines

Wi-Fi is short for wireless fidelity.  It is a short range wireless technology that enables computers and other devices to access the internet when in range of a wireless network connected to the internet.

Wireless broadband
Broadband services delivered through radio waves. 

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