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A-Z of Telecoms Terms

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A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

A

An Automatic Call Distributor (ACD) system is designed to distribute all incoming calls equally among a group of agents working in a call centre. The system allows agents to log in and receive calls. It also provides facilities to monitor the performance of individual agents and the call centre as a whole. Whenever a call comes in, the ACD system automatically routes it to the first available agent, whether the one who has been idle the longest or has just become free.
ADSL converts the copper pairs between the telephone exchange and the telephone socket into a digital line that only the subscriber can access. However, the speed of data transmission is different in both directions. Downloading is faster than uploading. It's important to note that ADSL will no longer be available after the PSTN Switch Off, scheduled for the end of 2025.
The principle of agents having their own 'users' within the phone system, enabling various settings, such as call groups, permissions, open/close times, etc., to be customised on a per-agent basis.
Assigning an alpha-numeric name to a facility can help identify callers. For instance, when receiving a call through an extension, the caller's name can be displayed instead of the extension number. Similarly, when answering an incoming DDI call, the name associated with the dialled number can be seen. This feature allows one person to answer calls in different ways, such as by using the names of other companies.
A single telephone line is used for both analogue devices and broadband. This is supported by the legacy PSTN network, which will be decommissioned in December 2025.
An ATA (analogue telephone adapter) is a device that can be attached to an ordinary analogue telephone line, such as a telephone, fax machine, cordless phone, answering machine, modem, etc. When switching to an IP or digital Internet connection, some analogue devices can still be used via an ATA (analogue telephone adapter).
An ATA, also known as an analogue telephone adapter, is a hardware device that connects a traditional telephone to the internet via a high-speed broadband line. It provides an interface to convert analogue voice signals into IP packets, delivers a dial tone, and manages call setup.
The option to (while a caller is on hold) speak with a colleague before transferring the colleague to the other colleague. This is ideal for agents needing to inform colleagues of call history or ask a specific question before transferring the call.
A voicemail feature that allows callers to be automatically transferred to extensions, or departments by dialling digits, available on tone-dialling phones. Callers are then prompted to select the desired extension or department by pressing the corresponding number. When callers are prompted to make multiple choices when being directed, this is known as a 'multi-level' auto-attendant.

B

The speed at which an internet connection can carry data. The more bandwidth, the faster the data transfer, which is usually measured in Mbps (Megabits per second) or Gbps (Gigabits per second).
A bit is the smallest piece of information that a computer can store. It's either a 0 or 1, which represents on or off. A byte is a collection of eight bits that can store more complex information such as letters, numbers, or symbols. For instance, the letter A is stored as the byte 01000001, composed of eight bits.
A short-range wireless transmission protocol used for connecting devices such as phones, computers, cars, and headsets, typically for audio and data transmission.
Automatically transferring a call to a different number based on a set of predetermined rules. For example, if a specific staff member is absent, calls could be directed to various colleagues depending on the caller's previous information or choices made through the IVR.
BLF are LEDs that provide a physical, visual indication of status of lines or extensions. For example, a red Light may indicate that someone's extension is busy.
A bolt-on is an additional service that can be added to your main licence or tariff, such as longer periods of call recording storage or advanced call queue features.
ISDN2 or BRI is the abbreviation for an ISDN circuit that provides two 64 kbit/sec bearer channels for data or speech and one 16 kbit/sec control channel. A BRI circuit can carry two independent calls simultaneously. Telephone systems (PBX) require the correct interface card according to the line type (ISDN2 BRI or ISDN30 PRI).
This is effectively a packaged deal. For example, with Virtual Landline Office you can get inclusive call minutes packages bundled with most licence types. See our licence table for more information.

'Bundle' is also an Ofcom definition, defined as a contract, or two or more closely related or linked contracts, between the provider of a Public Electronic Communications Service and an End-User, which: (a) relates, or together relate, to the provision of at least one of the following: (i) an Internet Access Service; or (ii) a Number-based Interpersonal Communications Service; and (b) also relates, or together also relate, to the provision of at least one of the following: (i) another service falling within paragraph (a)(i) or (ii); (ii) any other Public Electronic Communications Service; (iii) an Information Society Service; (iv) a Content Service; and/or (v) Terminal Equipment.

A measure of data. In Telecoms the definitions used are based on one Kilobyte (1KB) equal to 1024 bytes. One Megabyte (1MB) is the same as 1024 Kilobytes (KB) and one Gigabyte (1GB) is 1024 Megabytes (MB). Beyond that, there are terabytes (TB), petabytes (PB) and more.
Note: In other technologies (e.g. data storage), Kilobytes may also mean 1000 bytes and Megabytes (equal to 1000 KB), Gigabytes (equal to 1000 Megabytes etc.).

C

Preventing calls to certain numbers and destinations, (e.g. overseas calls or calls to premium rate numbers). This can be applied to the telephone system or at the network level on the line.
The ability to prevent calls from specific numbers from reaching your phone lines, usually managed via the management portal or by the service provider.
The time interval between when the phone is taken off the hook for a call and when the call is ended.
Call diversion, also known as call forwarding, allows an extension user to redirect incoming calls to another destination by dialling a code. The destination can be another extension, a group of extensions, the operator, or an external number, such as a mobile phone. Different types of call diversion are usually available, including Diversion of all calls, Diversion on busy, and Diversion on no reply.
A calling feature for inbound calls that will "roll past" a busy signal or try multiple numbers until the call is answered.
Data recorded about calls made or received through a telephone system. This data can then be used for reporting.
The use of software to analyse and report on call records, agent functionality, and call routing which are used to enhance the telephone system and caller experience, as well as identifying fraudulent call usage and other factors.
When a user parks a call, another user can retrieve it later. This feature is especially helpful when there are loudspeaker announcements, like "Telephone call for Joe Bloggs, please dial 811". If Joe goes to any phone and dials 811, he will be connected to the call that was parked for him.
The ability to record both audio and video data from a call to be used for future training, complaints handling, or due to industry regulation. Automatic transcriptions of conversations may also be included within a call recording, depending on the platform and service. Archiving refers to the ability to keep all necessary calls for a long-term period and access them as and when required.
Caller ID is the name and corresponding information attached to a particular incoming phone number.
A digital file containing call records including CLI, date, time, number dialled, destination, duration and cost. A CDR will be used to create and analyse bills.
Mobile, Voice or Connectivity network service provider e.g. BT, TalkTalk etc. Carriers own their infrastructure or network.
Cat 5 is a cable specification commonly used for cabling systems within business premises. It allows users to route voice and data circuits to any wall socket, and enables different computer and telephone systems to co-exist on the same cabling.
The box or cabinet housing the central equipment that controls the telephone system.
Centrex is a hosted telephony service that operates over a managed broadband connection delivering the functionality of a PBX without many of the costs and manageability issues.
A code is used in conjunction with a Coder and decoder to compress and decompress speech or audio signals for more efficient data transmission.
Typically, a red, yellow or green indicator informs teams whether colleagues are available to call, busy or away from their desks.
The software installed on a user's computer to make calls over the internet.
The capture of the caller's number. The CLI is associated with the line and is commonly known as the 'telephone number'. The CLI can be presented on outbound calls and withheld. The user can also use an alternative CLI to present on their calls.
A service that provides a called party with the calling line ID of the caller.
A CLIR would stop your own CLI (telephone number) from being presented to the person or business you are calling.
A cloud phone system runs on cloud computers rather than on-premise systems, and users connect via a private network or the Internet. They offer more flexibility and resilience and are typically subscription based rather than paid-for before installation.
COLP is a service that reveals the identity of the person you have connected to, even if the call is diverted. It provides the telephone number of the connected party and is a paid-for service that requires compatible equipment.
This is a term that is used to indicate the squeezing of data in a format that takes less space to store or less bandwidth to transmit. It is very useful in handling large graphics, audio and video files.
The joining together of more than two telephone users in a single call.
A conference bridge connects multiple parties over the phone. It can be standalone or built into a PBX. They balance the noise on each channel so everyone can hear each other. Advanced ones idle non-speaking parties and reject input signals. VoIP-based conference bridges are controlled by protocols such as SIP or Megaco and use RTP for media transmission.
A progression of the call centre merging customer calls with other media such as chatbots and email in conjunction with CRM applications, creating a more unified approach to customer service fulfilment, improving customer service levels leading to increased customer acquisition, satisfaction and retention.
Equipment that resides on the customer premises for the service to operate, e.g. a router for an Ethernet Fibre service.
A software application to deliver a single view of the customer. Customer records and information relating to the customer's account are recorded in the CRM, such as HubSpot, Salesforce and Oracle.

D

An inbound or outbound number assigned to a specific handset. The DDI will be associated with the main number (CLI) and is available on ISDN and VoIP.
A technology that provides greater clarity and smaller handsets for cordless phones.
Physical phones with a receiver that are hardwired into a business' phone network, typically for admin teams and user-specific desks. Most modern desk phones include the facility to log-in to specific user profiles, enabling Hotdesking without the need to switch desk phones around whenever users change desks.

A feature often used to provide an overflow if the switchboard operator is busy or absent. Incoming calls are sent to the operator but other extensions have delayed ringing, so they will start ringing if the call is not answered after a pre-set time.
A dedicated Ethernet fibre connection that connects to the Internet rather than to a private network.
The time interval, measured in milliseconds, between when a phone is taken off the hook and when a dial tone sounds.
A computer program running on a web server, translating domain names into IP addresses. Recently, special types of domain name records were added to the world-wide DNS system, to support SIP/VoIP (SRV/NAPTR, ENUM) protocols.
118 services used to discover a number for a specific business or person, depending on their listing and area.
A unit that fits alongside a telephone to turn it into an operator console that typically contains a large number of programmable buttons that can be used to call and to indicate the status of extensions.

E

An access technology delivering dedicated synchronous and uncontended bandwidth to a site over multiple copper MPF pairs. BT Wholesale's EFM reached end of life in November 2023.
An access technology delivering dedicated synchronous and uncontended bandwidth to a site over a 100mbps, 1Gbps or 10Gbps fibre bearer circuit. This bandwidth can connect a site to the Internet, used for dedicated site-to-site (point to point) or to a private network.

F

Fixed Line is often the term used when referring to a solution or product that uses the physical fibre or copper network as opposed to over-the-air technology such as 5G or Wi-Fi.
A feature that allows calls to find you wherever you are, ringing multiple phones (such as your cell phone, home phone, and work phone) all at once.
A part-fibre, part-copper Broadband access technology where fibre runs to the local cabinet, typically green street cabinet, that then uses legacy copper to link the cabinet to the user premises.
High-speed broadband access technology where fibre connectivity runs all the way to the building is referred to as FTTP in commercial settings and FTTH for residential users.

G

This technology uses a phone's GPS receiver to calculate your exact location on Earth from the orbiting satellites. It can also be used with smartphone mapping software to provide a navigation service.
Dialling a number rings a group of extensions. The group may be set as a ring group, in which case all the extensions ring at once, or it may be set as a hunt group, in which case the system will find a free extension in the group to take the call.
The mobile phone platform primarily used in Europe and many other countries around the world.

H

Cloud-based calling services, like Virtual Landline Office, which host equipment on a different premise, such as a data centre. One such example is hosted PBX, which is accessed through user licences paid by subscription. The handsets are kept on the customer premises, while the features and functionality are provided by the platform hosted in a data centre.
The principle of allowing staff to use any desk within a given room or office, instead of user-specific work areas, maximising office space and reducing underused square footage, while enabling greater collaboration and flexibility in how the space is used.
'Hot spots' are locations where mobile phone users can connect to the internet using Wi-Fi via a wireless access point.
Calls are directed to a hunt group which searches for a free extension to take the call. Hunting types include first free or terminal hunting (which gives priority to the first free extension) and circular or UCD hunting (which distributes calls equally over the group).

I

A unique 15-digit serial number that identifies an individual mobile phone. You can normally display this by typing *#06# on your phone.
A service that allows you to ´chat´ with another internet user in real time, by sending messages to each other. Examples include iMessage, WhatsApp etc.
Usually facilitated by an API or custom software, integrations allow different pieces of software to connect with each other to share information. For example, integrating your calling solution with your CRM would allow customer data such as caller IDs and previous interactions to appear within the calling platform for a more seamless agent experience.
A series of characters that uniquely identifies the terminal equipment, which is the origin or destination of data being transmitted. IPv4 is the most widely used but now an old variant with 32-bit addresses (e.g. 85.23.134.23). The emerging standard is IPv6, which uses a 128-bit address (e.g. 2001:0db8:85a3:0042:1000:8a2e:0370:7334). IPv6 allows for a worldwide pool of trillions of devices to be connected and addressed across the global public internet.
An IP phone is just like any other phone, but it converts voice into digital packets and vice versa to make phone calls over the internet instead of using the PSTN network. This is enabled by built-in IP signalling protocols such as SIP or H.323 that ensure that the voice is routed to the right destination over the net. IP Phones use audio or/and video codecs such as G.711 or/and H.261, respectively, over RTP, enabling value-added services like voicemail, e-mail, call number blocking, etc.
An organisation set up in business to connect a consumer or business to the internet.
ISDN lines come in two flavours: ISDN2 - offering two channels of voice. If more channels are required, several ISDN2 bearers can be presented over one number, and ISDN30 - a 2MB circuit divided into 30 channels. A minimum of 8 channels must be open; you can then increase capacity by two channels at a time without installing more bearers until you reach 30.
A service provider of Voice over IP (VoIP).
An IVR platform uses computer telephony components to translate callers' touch-tones or voice commands into computer queries after they hear an audio menu. IVR systems can also be used for callers to change information in a database.

J

It is a term used to indicate a momentary fluctuation in the transmission signal. This happens in computing when a data packet arrives either ahead or behind a standard clock cycle. In telecommunication. This may cause a momentary drop in call quality or potentially disconnect the call.

K

Kbps is the acronym for Kilobits per second and is used to indicate the data transfer speed. If the modem speed, for instance, is 1 Kbps then it means that the modem can route data at the speed of one thousand bits per second.

L

Enables PCs to communicate data between each other and common devices or servers also connected to the network usually within the same building, without connecting to the wider public internet.
An industry-regulated authority letter signed by the customer to allow their service provider to port their number to an alternative network (see 'Porting'). Sometimes referred to as a Customer Letter of Authority (CLOA).
Phone numbers that have typical UK 'area codes' but aren't necessarily located in that area. This means that businesses can have a phone number in a different location from where their office is located. For example, a taxi company in Manchester can have a London number that directs calls to their Manchester office. These phone numbers are only for incoming calls and don't need any equipment or lines.

M

A reference to the location where voicemail or email messages for a particular user are stored.
A website where admins and managers can log in to add new users, amend use permissions, change call workflows and make various other alterations to enhance the calling experience.
An API for Microsoft Windows which allows programs to become email-aware.
Multiprotocol Label Switching (MPLS) is used to connect a company's disparate sites over a private IP. Using a mechanism in high-performance telecommunications networks, MPLS directs data from one network node to the next based on short path labels rather than long network addresses, avoiding complex lookups in a routing table.
The same as the ICR mentioned above, but with the additional ability to understand (and potentially converse in) multiple languages.

An audio recording that plays to a caller on hold to reassure them that they have not been cut off. Typically music that may be interspersed with advertising messages or could be simply a reassuring beep played every few seconds.

N

A device allowing multiple devices to access a network. Switches come in 8-, 16-, 32-, and 48-port models.
Non-geographic numbers (NGNs) are telephone numbers which are not tied to a particular geographical location. Examples of NGNs are 0300, 0500, 0800, 0808, 0844, 0845, 0870, and 0871. Premium rate numbers also fall under the category of NGNs but are more expensive. These numbers are inbound only, which means they do not have any ability to make outbound calls.
Most telephone systems have at least two operating modes: day service and night service. These are typically used to route incoming calls to different destinations, play different Music on Hold messaging and potentially apply call barring to prevent unauthorised use of the phones out of hours.

O

The Office of Communications is the UK's communications regulator that oversees telecommunications, broadcasting and postal industries and would be the organisation to approach if there was ever an issue that you couldn't resolve with your provider. Find out more at Ofcom.org.uk.

P

On-premise telephone switching systems that interconnect telephone extensions to each other, as well as to the outside telephone network.
If you want to keep your current phone number when switching to a new mobile phone network, you will need a PAC code from your previous network to give to your new one. This code allows you to transfer your number to the new provider without any hassle, via a process called number porting.
Short for 'Payment Card Industry', PCI compliance is required to take card payments over the phone, and when recording a call certain information must not be recorded to ensure compliance. More information can be found here.

Porting is the name given to the process of transferring a phone number from one network provider to another network provider. Porting allows you to keep your number and is used for both fixed-line and mobile numbers. The process requires a LOA (letter of authority) from the end user.
The traditional 'landline' phone network, both commercial and government-owned, is known as the Public Switched Telephone Network (PSTN). In the UK, the PSTN network is scheduled to be turned off by the end of December 2025 in favour of internet-based calling solutions such as VoIP, UC and CCaaS.
A device with several ports available to connect multiple devices to the business network that also supply electricity to the devices. PoE switches come in 8-port, 16-port, 32-port, and 48-port models.

Q

A service level that is defined by the service agreement between a network user and a network provider, guaranteeing a certain level of bandwidth, resilience and/or data flow rates.

R

The principle of collating and analysing historical call data (call duration, frequency, call length, etc.) can then be used to better inform decision-makers on how best to staff and manage phone lines to maximise productivity and cost-efficiency.
Reseller Identification codes are allocated by Ofcom. These three-character alphabetic codes are used in the Notification of Transfer (NoT) switching process and can be used to identify a reseller of telecoms services.
Routers send data traffic to different devices and networks, typically acting as the bridge between public internet services and local networks within a premise, and can be either wireless or wired.
One of the protocols used to transport voice signals over a data connection.

S

Typically seen in inbound call centres, Screen popping describes the initialising and presentation of database information using the CLI. This reduces the time spent searching for customer service history by 'popping up' the calling customer's information when the call is answered by the agent.
The ability to share what a caller or agent is viewing on their computer screen with the other caller, and is commonly used in group video calls to collaborate on projects. It is also ideal for technical support lines when callers need help navigating their computer.
A group-wide contact list that everyone within a team or business has access to, ensuring all external contact information can be viewed.
SIP is a signalling protocol widely used for voice and video calls over the Internet. SIP trunks are typically connected to a telephone system.
An SLA is an agreement concerning a measurable level of service between the service provider and the service receiver.
An IP-only service that runs over the same technology as FTTC but does not require a separate analogue landline.
An IP connection service designed to bridge the gap between legacy WLR-based services and fibre services. It is only available where fibre services are not available, typically where replacing the existing copper infrastructure with fibre is not economically viable.
The ability to record a person's audio and transcribe that into the written word. This is useful in scenarios such as dictation, Interactive Voice Recognition as well as Voicemail-to-email.

T

TAPI, which stands for Telephony Application Programming Interface, is a standard developed by Microsoft Corporation. It enables communication between a computer terminal or workstation and a telephone extension. Keep in mind that there are different versions of the TAPI standard, and various options within it. Therefore, it cannot be assumed that all features of one TAPI-compliant device will be available on another TAPI-compliant device.
Set of communication protocols used to interconnect network devices on the internet or other networks.
Tethering describes the process of connecting a phone to a computer so that the computer can access the internet via the mobile phone's cellular network.
Also known as MF (multi-frequency) or DTMF (dual-tone multi-frequency), tone dialling generates audio tones when digits are dialled. These tones are sent down the line and can be detected by telephone systems or other devices to direct calls.
A telephone exchange line to receive and make calls.
A facility that allows an incoming call received on one line to be transferred to someone on another line. For example, to transfer an incoming call to someone's mobile phone.

U

A messaging platform that allows management of different electronic messages such as Chatbot, email, SMS from a single user interface, to improve efficiency as all messages are presented in one place to the user.

V

A protocol for separating devices on the same physical network.
The ability to have voicemail transcribed and sent to users via email so they can be read as-and-when is convenient to them, enusiring missed calls aren't forgotten.
A key protocol in facilitating voice calls over the internet.
This device serves as a bridge between the public switched telephone network (PSTN) and an IP network for both voice and fax calls. Its main functions include compressing and decompressing voice and fax data, packetizing the data, managing call routing and control signalling. It also offers an interface to connect with Gatekeepers or Softswitches, billing systems, and network management systems.
A VoIP phone transmits voice calls over the internet by converting voice data into IP packets. It can be a physical device or a software application installed on a PC, known as a Softphone. Softphones require calls to be made from the PC, not a telephone.
VPNS provide users with secure and private inter-site communications over the internet by masking the IP address of the user.

W

Typically displayed on a TV screen, wallboards give agents and team leaders real-time information about productivity, for example, wait times, queue lengths, agent performance, etc., for a better understanding of current performance.
A network that extends over a large geographical area connecting multiple Local Area Networks together. The Internet can be considered as the world's largest WAN. A private WAN can be created to connect users in different sites to access the same information as if they were all connected locally on the one Local Area Network (see 'ISP' and 'MPLS').
A means of accessing the internet using a mobile phone.
The ability to invite hundreds of contacts to watch a live presentation and interact with the presenter, just like if everyone was in a lecture hall together.
Wi-Fi is a WLAN (Wireless Local Area Network) technology. It provides short-range wireless high-speed data connections between mobile data devices (such as laptops, tablets or phones) and nearby Wi-Fi access points (special hardware connected to a wired network).
Offered to telecoms resellers by BT to take ownership of a BT line rental, allowing them to offer a one-bill solution and discounted pricing. Using the Openreach network, a customer could change their service provider seamlessly. The WLR service is being retired in December 2025.

X

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