It’s easy to get snowed under by the jargon. Here’s a quick run-through of the terminology you might come across:
ACD
Automatic Call Distribution – a specialised phone system used for handling many incoming phone calls and then distributing the calls between available staff in a logical pre-programmed pattern. It also keeps records and tracks what it does with great accuracy for future reference.
Auto attendant
A device or a feature of some PBXs and phone systems that answers a call and lets the caller route their call to a specific extension or group, typically by inviting the caller to press number keys on their phone to select options. No human intervention is required.
Automatic route selection
Or ARS. This feature automatically chooses the least expensive phone line to the destination.
Cabinet
The box (usually wall mounted) that contains the control circuitry for a PBX system. May be called the Key Service Unit (KSU) or Central Control Unit (CCU).
Call recording
The ability to record both sides of a telephone call for staff training and security purposes, with call data being stored locally or in the cloud for periods of up to 7 years or more. PCI-compliant call recording ensures that the recording is paused whilst payments are taken.
Call forwarding
Feature which allows an incoming call to be sent elsewhere.
Call hunting
If a particular extension is not picked up after a specified interval, an incoming call can be passed on to nominated alternatives.
Centrex lines
Service offered by the local phone company from their local central office. It basically provides many of the features you’d expect from a PBX; they can include call forwarding, intercom, call transfer, toll restrictions and least-cost routing.
CLI
Caller Line Identification. A facility where the incoming call provides the telephone number it is dialling from. Known as Caller ID in the States.
Cloud
In simple terms, cloud just equates to the internet. With cloud telephony, this means using the internet instead of traditional copper wire to transmit voice communications; in computing terms, cloud means accessing and storing software programs and data over the internet instead of using your PC/MAC hard drive.
Conferencing
Connecting three or more people in a single phone conversation.
Cord
Can refer to the curly cable that goes from the phone to the handset or to ‘line cord’ – the flat cable that runs between a wall socket and the phone.
CTI
Computer Telephony Integration. The ability to connect a computer to a telephone or business communications system.
Data port
Or more simply ‘port’ – a point of access to a computerised system for transmitting or receiving data. Basically it’s a socket.
DDI
Direct Dial Inward – dialling a specific number to reach a specific person or department even though the call actually goes through a switchboard or PBX (In America and Japan this is called DID, Direct Inward Dial).
DECT
Digital Enhanced Cordless Telephony – a standard for cordless voice (and data) transmission using radio waves. Users can make and receive internal and external calls from anywhere on the premises if they are in range of any of the strategically positioned ‘base stations’.
Default
The original settings of a programme or some other configurable system. Same as ‘factory settings’.
Dial tone
The tone that is heard when accessing an outside line.
Digital
Digital technology means that sound is transmitted as bits of data rather than audio waves, and in theory this has many advantages – much clearer transmissions, for instance.
DISA
Direct Inward System Access. A person can call into the phone system and access its features without operator assistance. This can include making long distance calls or just calling another extension.
DSS
Direct Station Select. This function (typically a set of buttons) allows the operator to call or transfer a call to a particular extension with a single keypress.
DTMF
Dual Tone Multi Frequency. Tones that are heard when dialling on an outside line or single line phone.
Extension
A unique number that identifies a phone – in practice, each telephone in a phone system.
Gateway
A facility that connects networked computers to the telephone system.
Handsfree
Some phones (‘speakerphones’) have a built-in microphone and loudspeaker so that you can talk on the phone without picking up the handset.
Hookswitch
The mechanical or electrical switch that terminates a call. The handset usually depresses the hookswitch when it is returned to the cradle.
Hosted
Telephone services that are ‘hosted’ within virtual data centres and accessed via the cloud using broadband internet or mobile 3G/4G/5G data services.
Intercom
Sometimes abbreviated to ICM. Internal communication using the phones.
ISDN
Integrated Services Digital Network. An all-digital network that runs as an alternative to the standard analogue system, providing multiple channels per line and high-quality voice and data connections at a premium price. All ISDN services are due to be terminated globally before the end of 2025, and replaced by cloud communication platforms such as SIP.
IVR
Interactive Voice Response. The ability to direct callers to a specific application on the system by inviting them to speak or press touch-tone buttons on the phone.
Jack
Or modular jack. The socket into which a telephone can be plugged. The most common types of jack – and therefore the most common styles of plug and socket – are RJ11, RJ45, and BT431.
Key set
A telephone with buttons that can be used for call holding, auto-dialling, line pick-up and other features.
Key system
A small type of phone system. Key systems typically use buttons or keys to access different outside lines.
KSU
Key service unit. The main cabinet that holds all of the switching electronics of a business phone system.
Last number redial
Or LNR. Hit the button and the phone will redial the last number you tried.
Least cost routing
Or LCR. This feature automatically chooses the least expensive phone line to the destination.
Line cord
The cable that goes from the wall socket to a phone.
Lines
Connections to the outside phone network. The number of lines determines the number of incoming and outgoing calls that can simultaneously occur.
Live call screening
Allows a user to monitor incoming calls as they are being recorded in their voice mailbox.
MDF
Main distribution frame. The panel where cables from the KSU are terminated.
Message waiting
An indication on the phone (a lamp or a displayed message) that there’s a message for the owner of the phone.
Modem
A device which converts digital signals (from a computer) into analogue form (for transmission over the telephone network). At the other end of the link another modem performs the reverse process.
Music on hold
Background music or messages heard when someone is put on hold.
OPX
Off-Premises Extension. A telephone located away from the phone system but still accessible from it – so an incoming call could be routed to your number whether or not the phone was physically located in the building.
PBX/PABX
Private Branch Exchange/Private Automated Branch Exchange. A switch used inside a private business as opposed to one serving the general public. Typically you have to dial 9 to get an outside line with a PBX telephone system.
PSTN
Public Switched Telephone Network. This encompasses analogue telephone lines typically located within domestic homes and business premises using copper wire; older ADSL internet services are also delivered using these lines. All PSTN services are due to be terminated globally before the end of 2025, and replaced by cloud communication platforms such as SIP.
Reset
Unplugging or turning off the power to a device, before reconnecting to power up again.
Screen popping
A facility in some CTI where a call arrives at a user’s desktop and the caller’s details are automatically retrieved from a database to ‘pop up’ on the recipient’s screen.
SIP trunks
Session Initiation Protocol. These are virtual VoIP telephone lines usually hosted in the cloud and connected to a telephone system via a broadband or leased line internet connection.
SoGEA
Single Order Generic Ethernet Access. Up until now, to deliver broadband to a home or office, you needed to have a traditional analogue phone line installed. SoGEA broadband doesn’t run over a phone line, SoGEA is a dedicated line that delivers a broadband internet connection.
TAPI
The telephony interface provided by Microsoft.
Touch tone
The tones that are generated when dialling out or pressing a number on the dial pad.
Two-way recording
The ability to record your phone conversation.
Two-way transfer
Permits an extension user to record a conversation in another person’s mailbox.
UC/UCaaS
Unified Communications or Unified Communications as a Service. This is the very latest in cloud hosted telephony solutions, and allows businesses and call centres to utilise a blend of voice, video, live chat, email and even social media messaging to provide a unified, cohesive communications experience with their customers.
Voicemail
A facility that answers calls and allows the caller to leave a message. It may also enable an internal caller to send inter-office messages to multiple recipients. Most systems allow employees to retrieve their messages from other phones both inside and outside the office.
VoIP
Voice over IP (Internet Protocol) is the latest buzz in the telecoms world. This technology allows telephone call traffic to be routed over the data network within an office and even between office locations using either leased lines or broadband/ADSL internet for free calls.
