• Stands for ‘Asymmetric Digital Subscriber Line’. ADSL transforms the existing twisted 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.

Analogue Line

  • See PSTN

Auto Attend

  • An automated system designed to guide a caller through the options of a voice menu. Typically set to answer and route incoming calls.


  • The capacity of a telecom line to carry signals. The necessary bandwidth is the amount of spectrum required to transmit the signal without distortion or loss of information. FCC rules require suppression of the signal outside the band to prevent interference.


  • Stands for ‘Basic Rate Interface’ – see ISDN2e


  • A term used to describe fast internet access. Wide bandwidth which can be either ADSL or SDSL. ADSL can suffer from vast bandwidth changes (see also Contention Ratio).

CPS – Carrier Pre Select

  • Uses network access technology so call traffic originating from your site will be routed
    directly to your chosen network with no need for prefix codes. The selection of the preferred
    provider is done automatically at the point of entry (the local exchange) to the public voice


  • 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.


  • 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.


  • Stands for ‘Basic Rate Interface’ – see ISDN2e.


  • Stands for ‘Direct Exchange Line’ – see PSTN.


  • A very common method of networking computers in a LAN. An ‘Ethernet’ describes the physical network that carries data traffic.

Exchange Line

  • See PSTN

Feature Line

  • A BT specific service running over the PSTN. Designed for small companies (typically max 3 users), it is a dated 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.

Hosted Telephony

  • What is Hosted Telephony? (aka Hosted IP Telephony).
    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 configured via a simple 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. All calls made between customer sites are FREE.
    ** The quality of the internet connection is critically important and it is recommended to keep the voice and data on separate internet connections.

Hunt Group

  • Multiple phones allocated to a single extension number thereby enabling a call to be answered by one person with a group. I.e. accounts or sales etc. Calls will generally ‘hunt’ from one phone to another until answered.


  • 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.

IP Telephony (also see Hosted Telephony)

  • 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.

ISDN (provided in two formats as per below)

  • 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 customers PBX. ISDN can also be used in Radio and was historically used for faster Internet connection before the advent of broadband.


  • Provided in pairs i.e. 2 channels/lines per ISDN2e. 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 ‘Local Area Network’ – Data network that connects computers, servers, printers etc together, generally within one physical location.

Leased Line

  • Dedicated private internet access circuit – provides secure, fast and uncontended internet access.


  • Stands for ‘Multi Protocol Label Switching’ – A flexible and cost effective way of providing a WAN.


  • Public (Automated) Branch Exchange aka Switchboard aka Phone System.


  • Stands for ‘Plain Old Telephone Service’ – see PSTN.


  • Stands for ‘Primary Rate Interface’ – see ISDN30e


  • Stands for ‘Public Switched Telephone Network’. This is the standard telephone service provided over basic analogue phone lines.


  • A device (or, in some cases, software on a computer) that directs IP packets to the next point toward their destination.


  • Stands for ‘Symmetric Digital Subscriber Line’. The same as ASDL but provides the same speed/bandwidth in both directions. Useful for companies needing to upload high bandwith packets quickly. Common requirement with VOIP networks.


  • Stands for ‘Simple Mail Transfer Protocol’. The standard Internet protocol for transferring electronic mail from one computer to another.

Unified Messaging

  • Enables you to access voice, fax, and text messages via one single email or telephone account.


  • 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).

VOIP (see Hosted Telephony)

  • 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 ‘Wide Area Network’ – Connects multiple LAN’s together, typically via VPN’s over broadband and/or Leased Lines – (The Internet is actually a WAN itself).