We've listed below some of the common terms used in the telecoms world. We hope you find this a useful source of information.
Stands for ‘Asymmetric Digital Subscriber Line’. ADSL works by using the frequency spectrum above the band used by voice and telephone calls, to transmit data. Essentially turning the copper pairs between the telephone exchange and the telephone socket into a high-speed digital line, allowing Broadband access. ADSL delivers fast download speeds but slow upload speed.
A simple copper phone line with a maximum data transfer rate of 56k. Used for phone calls, alarm monitoring, fax and PDQ machines but more commonly for ADSL broadband connections. In the past it was possible to transmit data using a 56k dial up modem (see Bandwidth below). However, the invention of ADSL technology allows for far higher bandwidth rates using higher frequencies.
Rejects incoming calls where the caller withholds their number.
An automated system designed to guide a caller through the options of a voice menu. Typically set to answer and route incoming calls.
A measurement for the maximum data transfer rate of a network, including an Internet connection. In simple terms it’s how much data can be transmitted in a given amount of time and is typically expressed in bits per second. Kbps is Kilobits per second and Mbps is megabits per second. K being 1,000 and M being 1,000,000. Therefore, a 70Mb connection (70,000Kpbs) is receiving 70 million bits of information per second. See ‘Bits vs Bytes’ below.
Bits are generally used to measure data transfer rates (see above) and Bytes are used to measure data capacity and storage. 1 Byte consists of 8 bits. In written form a Byte is depicted with a capital B and a bit is depicted with a lower-case b. For example, 1MB means 1 Megabyte (size) but 1Mb means 1 Megabit (speed).
Some people may think a 70Mb (Megabit) internet connection should be able to receive a 70MB (Megabyte) file in one second. However, 1 Byte is 8 bits, and so a transfer rate of 70Mb is only capable of receiving a 8.75 Megabytes of data in a second. Ergo it would take almost 2 mins to receive a 1GB file using a 70Mb connection.
A term used to describe fast internet access. This a generic term that covers and internet connection using any access meth other than ‘dial up’ (aka narrowband). In reality, most people would now consider basic ADSL to also slot into the narrowband category since most of the population has become used to much faster internet connections via Fibre to the Cabinet, Fibre Leased Lines and 4G.
Sounding far more intrusive than it actually is, this facility allows specified users to join an active call and therefore create a three-way call. The person barging in can choose to mute their handset before joining the call, thus creating a ‘silent call monitoring’ scenario. There are normally a set of users (managing users) that are set up to be able to ‘barge’ in on active users (monitored users). Most PBX’s provide a ‘beep’ when someone joins a call, in order to alert the other users. Some PBXs allow you turn the beep off.
Prohibits a phone or system from dialling certain destinations or codes. Normally used as a means to reduce costs and/or prevent fraud.
Allows you to divert calls to almost any phone - anywhere in the UK, most overseas destinations or a mobile phone!
A service feature that enables a user to retain an existing call, while accepting or originating another call using the same handset or phone device. The held call is tied to the handset that placed the call on hold and, therefore, can only be taken out of hold from the same handset.
A feature that allows a user to make an announcement to numerous users simultaneously using the speaker on each handset. This is a one-way transmission, i.e. only the caller can speak. Similar to a tannoy system in a warehouse.
A service feature that allows a user to place an active call on 'hold' at one telephone handset and then retrieve the call from any other handset within the same phone network. The call is effectively placed in a 'parking bay' and is allocated a bay number, e.g. 101. Users can then pick up another handset on the same network and type in the bay number to retrieve the held call.
The ability to take a call that is currently being presented on another phone or phones. The ringing phone(s) need not necessarily be in the same physical location as the user wishing to pick up the call. In this instance the user would be aware of another ringing phone by an indication on their own handset.
A Call Queue Group is essentially a Hunt Group with the ability to queue calls, should all users in the Hunt Group be busy. Call Queue Groups would normally have music/messages played to callers whilst they are held in the queue.
A service feature that allows a user to place a call on hold whilst, simultaneously, transferring the call to another destination. The destination can typically be either an internal or external telephone.
A tone or message that alerts you that someone is trying to call when you’re already on the phone.
Displays the number calling you.
Allows multiple callers to participate in one phone conversation simultaneously.
A term used to describe the number of individual broadband customers connecting to a single internet node at the local public exchange. Different contention ratios will cause vast speed differences, as higher ratios normally equate to slower speeds. This can often vary depending on time of day and number of users online.
Historically, Voice & Data networks were kept entirely separate. However, in recent years, changes in technology have meant that many businesses can now run both voice and data over the same LAN, thereby causing them to ‘converge’. Cost savings are one benefit of Convergence but far more importantly there are significant productivity and efficiency gains to be achieved. VOIP, IP Telephony, Unified Messaging, Remote Working etc. all come under the ‘Convergence’ umbrella.
Communications Provider. Any company able to provide telecoms products and services.
Customer Premises Equipment. Meaning devices, extension sockets, cabling, routers, switches etc, which are on site at a customer location. Typically the responsibility of the customer.
Stands for Communications Provider Identity. This is a unique identifier allocated to communications providers by Ofcom.
Stands for ‘Direct Dial Inbound’ – allows users to rent individual phone numbers without the need to rent individual lines. DDI’s are mapped onto specific ISDN lines and the PBX is then programmed to direct the incoming DDI call to the specific extension or hunt group as required. Customers can rent a large volume of DDI’s whilst benefiting from renting an optimum number of lines based on required usage.
Stands for ‘Digitally Enhanced Cordless Telecommunications’. A technology used to link cordless mobile handsets to a wired telephone system.
Another term to describe an Analogue Line and stands for ‘Direct Exchange Line’
Directory Enquiries.
The most common method of networking computers in a LAN. 'Ethernet' describes the signalling protocol used within a network that carries data traffic.
See ‘Leased Line’
End User. Normally used in connection with number porting – denotes the person/legal entity that is entitled to port a number.
Another term to describe an Analogue Line.
A BT specific service running over the PSTN. Designed for small companies (typically max 3 users), it is an outdated product that provides limited basic PBX functionality requiring one dedicated phone line per user. Featureline is not considered to be cost effective for 4 or more users.
This is a generic term for any broadband service that uses fibre optic cable, in place of traditional copper wiring, to connect a telephone exchange to the 'green cabinets' in the surrounding roads. This means that copper wires are only used in the last few hundred metres between a green cabinet and a customer's premises. Unlike copper, fibre is extremely fast, does not suffer from signal loss over distance, or is susceptible to interference caused by severe weather. Therefore, provides much faster download and upload speeds and greater bandwidth.
This means that the entire broadband service is provided on fibre optic cable, from the telephone exchange into the premises. Typically, you can expect noticeably higher speeds on FTTP services.
Hosted Telephony (aka Hosted IP Telephony) is an IP based phone system that is "hosted" in a data centre. Customer sites connect to the hosted phone system via an internet connection that is generally either ADSL or SDSL but can be a leased line. All the intelligence of the phone system is held within the data centre and the on-site equipment is controlled by the central system. Customer communication profiles are normally configured via a web-based browser and individual users can control their own phone profile from any internet connection, with ease.
Hosted Telephony is particularly beneficial for companies with two or more sites and can be used internationally. Hosted Telephony licenses often now include free calls.
The quality of the internet connection is critically important, and it is often recommended to keep the voice and data on separate internet connections.
Multiple phones allocated to a single DDI or extension number, thereby enabling an inbound call to be answered from any phone within the allocated group of phones, i.e. accounts or sales departments. Inbound calls can be configured to ‘hunt’ from one phone to another (until answered) or to be "broadcast" across all phones in the group, so they all ring at once.
Stands for ‘Information and Communication Technology’. Equipment such as computers, the Internet, CD-ROMS and other software.
Stands for ‘Internet Protocol’. A standardised method of transporting information across the Internet in packets of data. It is often linked to Transmission Control Protocol, which assembles the packets once they have been delivered to the intended location.
Using Internet Protocol as a method of carrying voice calls. With IP, voice communications (in the form of IP packets) are routed directly from the origin to destination devices.
Stands for ‘Integrated Services Digital Network’. Digital telephony service that gives better call quality, quicker connection times and DDI facilities. ISDN is generally provided to connect to a customer’s PBX. ISDN can also be used in Radio and was historically used for faster internet connection before the advent of broadband.
Openreach have announced plans to discontinue this service by 2025.
Provided in pairs i.e. 2 channels per ISDN2e line. The majority of customers would get a maximum of 4 pairs before moving up to ISDN30e. The e stands for the European standard.
Provided over one large circuit (bearer/pipe) either as copper or in many cases fibre optic. The minimum number of channels/lines one can have is 8 moving up to 30. Larger organisations can rent multiple ISDN30e’s should they require more lines. The e stands for the European standard.
Stands for Interactive Voice Response. A facility that allows a computer to interact with users through the use of voice and/or tones input through a keypad. Often used with Auto Attendants and voicemail services.
Stands for ‘Local Area Network’ – a data network that connects computers, servers, printers etc. together, generally within one physical location.
A measure of delay. In a network, latency measures the time it takes for some data to get to its destination across the network. It is usually measured as a round trip delay (RTD)- the time taken for information to get to its destination and back again. Network latency is measure in milliseconds. A telephone call requires a latency of 80ms or less to work effectively. After that the speech delay becomes noticeable to the human ear and is no longer an effective mechanism for a conversation.
A dedicated private internet access circuit – provides secure, fast and uncontended internet access for the exclusive use of the end user. Historically these have been very expensive, but costs are coming down rapidly, putting leased lines within the reach of many smaller businesses.
Stands for Local Loop Unbundling. The process whereby the network operators (Openreach and Kingston Communications) make the local network available to other companies, so that they may in turn rent them to end users.
Stands for ‘Multi Protocol Label Switching’ – A flexible and cost-effective way of providing a WAN.
Stands for Non-Geographic Number. A number that normally begins with 08 or 09, and is therefore not linked to a specific geographic location (or, more accurately, a telephone exchange)
Ofcom is the regulatory body for communications services in the UK. Amongst other things they are responsible for setting out various rules and regulations to which the communications industry must adhere. They also handle complaints and disputes between customers and communications providers.
Public (Automated) Branch Exchange aka Switchboard aka Phone System. A phone system that is located on the end user’s premises, to which are connected the incoming lines and telephone extensions. The system manages the routing and handling of inbound and outbound calls, as well as internal calls.
The process by which a specific telephone number or numbers are moved from one supplier to another. This enables end users to change suppliers or telephony platform whilst retaining their phone number.
The porting of a number is led by the gaining communications provider, and the end user should expect to be asked to sign a document giving their authority to port the number.
Stands for ‘Plain Old Telephone System’ - another term to describe an Analogue Line.
Enables the option of ‘masking’ the main outbound number of a telephone line with a different number. This option is useful for call centres or companies that are located in obscure locations and don’t want end users to know their physical location, or if they want to present a non-geographic number to the customers they are calling. For example, a company may have a number beginning 0207 but they want an 0845 number to be displayed to every end user that they call.
Stands for ‘Primary Rate Interface’ – see ISDN30e.
Stands for ‘Public Switched Telephone Network’. This is the generic term for the public telephone network provided by multiple carriers.
A device (or, in some cases, software on a computer) that directs IP packets to the next point toward their destination.
Stands for 'Session Initiation Protocol'. It is essentially a communications protocol used to set up and clear down sessions with one or more users over the internet. Can be used in a multitude of scenarios, but most common is in the initiation and termination of Voice over IP calls.
In simple terms, an internet phone line. A SIP trunk is a virtual link between an IP PBX (usually at a customer site or data centre) and a network operator, which is designed to carry private SIP traffic (VoIP phone calls). Each trunk contains SIP channels and each phone call requires one channel. There is no limit to how many channels can be provided on one SIP trunk. SIP trunks are much cheaper to rent than traditional phone lines and also offer vast scope in terms of DDI number allocation and management.
Stands for 'Service Level Agreement' - part of a service contract where the level of service is formally defined. In practice, the term SLA is sometimes used to refer to the contracted delivery time (of the service) or performance.
Stands for ‘Simple Mail Transfer Protocol’. The standard Internet protocol for transferring electronic mail from one computer to another.
Enables you to access voice, fax, and text messages via one single email or telephone account.
A voice portal allows a user to access voicemail services from any phone. The portal would be accessed via a dedicated telephone number, and will normally allow the user to listen to messages, change their greeting(s), change passcodes etc.
Stands for ‘Voice Over Internet Protocol’ - voice translated into data packets and transmitted across an internet connection or network - just like any other file or email you might send. Upon reaching the other end data is transformed back into its original form and emerges like a regular phone call. (VOIP is critically dependent upon the speed of the packets across the internet and the correct assembly order once they arrive at their destination…for obvious reasons!)
Stands for ‘Virtual Private Network’ – a way of creating a private communications network over a public network (mostly the internet) using secure protocols (passwords, authentication methods etc.)
Stands for ‘Wide Area Network’ – Connects multiple LAN’s together, typically via VPN’s over broadband and/or Leased Lines – (The internet is a WAN)
Directory entry held in the BT Phone Book and from Directory Enquiries (118 services)
Not in the BT Phone Book or held on Directory Enquiries
Not in the BT Phone Book, but is held on Directory Enquiries (118 services)
Not in the BT Phone Book, and not disclosed by Directory Enquiries. The operator will offer to call the customer for persistent enquiries. Note that this is a chargeable service.
No directory entry is made. This option is usually used for lines that are not intended to receive calls, e.g. lines solely used for alarm systems, modems etc.
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