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Jargon Buster

The telecoms world is full of Jargon, quickly find the meaning behind all those acronyms here...
0-9 | A | B | C | D | E | F | G | H | I | J | K | L | M | N | O | P | Q | R | S | T | U | V | W | XYZ


1 Eared

A headset with one earpiece. See Monaural for definition.

2 Eared

A headset with two earpieces. See Binaural for definition.


2.5mm plugs are standard round plugs. Commonly used on mobile and cordless phones as well as a few business telephones.


3.5mm plugs are standard round plugs. Less commonly used than the 2.5mm plugs, these are used on some business telephones.


A2DP is a Bluetooth profile and is short for "Advanced Audio Distribution Profile". This profile defines how audio multimedia can be streamed from one device to another over a Bluetooth connection. A2DP is also known as "Bluetooth Audio Streaming".


AA is an acronym for ‘Auto Attendant’. Please see Auto Attendant for definition.


ACD is an acronym for ‘Automatic Call Distribution’. Please refer to ‘Call Hunt’ for more information.


This stands for an ‘Advanced Connectivity Interface’. This term simply refers to all modern telecommunications systems.

Acoustic Clarity

Acoustic Clarity is Polycom's patented Duplex technology, which enables a more natural conversation.

Acoustic Shock Protection

Acoustic Shock Protection (ASP) is the prevention of harm to hearing caused by acoustic shock, which is simply sudden & unexpected loud noises experienced via the telephone. Devices with this feature limit noise to 85dB. ASP is a voice circuit breaker that uses Digital Signal Processing (DSP) to protect users from these sounds.


ActiveGard is the Sennheiser Trademark name for 'Acoustic Shock Protection'. See Acoustic Shock Protection for more info.


ADA is shorthand for the ‘Americans with Disabilities Act’. ADA-approved phones ensure accessibility for disabled individuals, through the inclusion of large buttons, visual and amplified ringers, and/or Braille.


ADF is shorthand for the ‘Automatic Document Feeder’. This is commonly found in fax machines and printers and is used to feed the machine with documents for printing.


ADSL stands for “Asymmertic Digital Subscriber Line”. ADSL is a data communications technology that allows for fast data transfer over telephone lines. In ADSL, bit rate and bandwidth are said to be Asymmetric, which means it is more focused towards the customer premises (downstream) rather than the reverse (upstream).


AEC, short for Acoustic Echo Cancellation, is a technology used to stop acoustic feedback between a speaker and a microphone in loud-speaking audio systems such as speakerphones, conference phones, hands-free mobile devices and voice controlled systems.


An amplifier is a device that ampifies sound. In essence, it makes things louder. Amplifiers are commonly used with telephones as they are able to boost the sound emanating from the telephone to the headset. Modern headset amplifiers are also digital which enables them to do other fancy things such as providing Acoustic Shock Protection.

Analogue System Supported Featurephone

These BT peripherals (often referred to as ‘ASSF’) are multi-line, or ACD, terminals which can handle many calls .


Analogue telephones and conference phones are simple 2 wire devices that can be used on a standard BT home line. Many analogue devices are compatible with digital and IP systems but will require the correct extension. You will need to contact network / IT team to find out which extensions you require.


ANC is short for Active Noise Cancellation. ANC is a method for reducing unwanted ambient noise.


ANR stands for "Active Noise Reduction". An ANR headset has a microphone inside the ear cup that picks up ambient noises. Sound is passed through electronics which produce a mirror image of the ambient sound at a non damaging decibel.


AOM stands for 'Add On Module'. An Add On Module is a module that can be added to a telephone to add additional functionality such as a large number of programmable keys to be used as shortcuts.


This stands for ‘Application Programming Interface’, a software-based interface which allows one program to interact with another.


This stands for ‘Analogue Private Network Signalling System’. An APNSS is the analogue version of DPNSS, a private networking standard.


APT stands for "Analogue Proprietary Telephone". This is an analogue telephone that is designed for use with a specific system or manufacture.


"ARMS" is short for 'Automatic Remote Monitoring Service'. ARMS enables full automated monitoring to allow generation of reports. Faults such as a damaged handset or telephone knocked over will trigger a call to the management computer.


ASP is short foo 'Acoustic Shock Protection'. Please see Acoustic Shock Protection for more information.


This means ‘Analogue System Supported Featurephone’. Please see Analogue System Supported Featurephone.


ATC is an acronym for ‘Audio Tele-Conference’. Please refer to ‘Conferencing’ for more information.


Attenuation is the noise level that is removed from your environment, allowing you to work safely in high noise areas. More scientifically, it's the process of losing noise energy. There are three levels of protection:
Low attenuation Low Attenuation
Allows you to work in areas of exposure to noise levels between 87db(A) and 98db(A).
medium attenuation Medium Attenuation
Allows you to work in areas of exposure to noise levels between 94db(A) and 105db(A).
High attenuation High Attenuation
Allows you to work in areas of exposure to noise levels between 95db(A) and 110db(A).


ATEX approved equipment has been specially designed and tested to work in explosive and dangerous atmospheres.


For telephony, ATM is an acronym for ‘Asynchronous Transfer Mode’. This is standardised digital transmission technology that can transfer all information types very quickly through a single network.

Auto Dial

Auto dial is the name given to electronic hardware and software that dials numbers automatically. Once calls are answered, either a recorded message will play (this is sometimes known as ‘robocalling’ or ‘voice broadcasting’), or a human operator will interact with the called party.

Auto Attendant

Also referred to as an ‘AA’ or ‘virtual receptionist’, auto-attendant automatically transfers callers to certain extensions without the need for human intervention. The majority of AAs provide a simply menu of options for callers to choose from – pushing ‘1’ may take a caller through to a billing department, for example, while ‘2’ may transfer them to customer services.

Automatic Call Back

This computer-telephony feature gives those who ring a call centre (or other business premises) during a busy period the option to be called back later. Instead of a caller spending a frustrating length of time in a call queue, automatic call back will store the incoming number and dial it as soon as an operator becomes free.

Beam Forming Microphone Array

A product with multiple microphones can be aligned in an array to form a directional beam pattern. This enables the product to be more sensitive to sound coming from one or more directions.


Please refer to ‘Busy Hour Call Completion’.


Binaural is used to describe a headset with two ear ear pieces.


Bluetooth is a wireless technology standard usually associated with mobile phones. Bluetooth benefits from high levels of security, but is only effective over short distances.


BLF stands for 'Busy Lamp Field'. A Busy lamp field is a row of programmable keys that indicate whether a colleagues phone line is busy or not, usually by the use of a colour LED.

Busy Hour

This is the hour of the day that a telecommunication system handles the most calls.

Busy Hour Call Completion

Also referred to as BHCC, this measurement represents the maximum number of calls a telecommunications systems can handle during a business’ ‘Busy Hour’.


BRI stands for “Basic Rate Interface”. A BRI is an ISDN (Integrated Services Digital Network) configuration.


Call Forwarding

This feature allows calls made from one number to be easily forwarded to another. This feature is useful for putting callers through to appropriate individuals and/or departments.

Call Hold

This telephone feature allows operators to pause a call, while they seek additional information for the caller, or activate another feature (Call Pickup, for example).

Call Hunt

Call hunting is a method of distributing phone calls from a single telephone number to different extensions sharing the same line. Supported by many PBX systems and available from a number of service providers, call hunting uses an algorithm to direct calls to free lines efficiently. Call hunt is also known as Automatic Call Distribution (ACD).

Call Park

This telephone feature allows an operator to place a call on hold from one terminal, and send it to an unused extension number so the call can be answered from elsewhere. For example, a department of a supermarket might be called from head office and told they have “a call waiting on 452” – the department would then dial 452 to attend to the call.

Call Pickup

This feature allows employees to answer ringing phones they hear located at unattended terminals, simply by lifting their own respective handset. Caller ID Also known as calling line identification (CLID), calling number identification (CNID), calling line identification presentation (CLIP) and calling number delivery (CND), caller ID functionality is present on a variety of analogue and digital phone systems. It allows a name (if available) associated with a number to be transmitted to the called party during ringing (and vice versa), which is then displayed on a telephone’s built-in screen, or another device.


CAS – or ‘Channel Associated Signalling’ – is a type of digital signalling which uses routing information to send audio and other data to its destination.


This stands for ‘Computer Assisted Telephony’, which simply refers to telephone systems which make use of computer technology. CAT is also referred to as ‘CTI’ and ‘CIT’.


CAT-Iq is an acronym of 'Cordless Advanced Technology – internet and quality'. CAT-Iq was designed to be fully backward compatible with DECT and allows IP voice to operate within the DECT framework, which enables high quality Widebad VoIP.


CIL means ‘Call Information Logging’, a feature which automatically records information about calls made from, and received by, a terminal or extension.


CIT stands for ‘Computer Integrated Telephony’, another way of referring to ‘CAT’ (Computer Assisted Telephony).


CircleFlex is a Sennheiser trademark. It refers to a technology that allows the ear cups to rotate the ear pads in order to adjust automatically to your head for greater comfort.

Class of Service

Class of service is a traffic management method which groups similar data types (email, audio etc.) together as ‘classes’, each of which can be given its own service priority level, to ensure business deals with queries of the highest priority first.


This stands for ‘Calling Line Identification’. See ‘Caller ID’ for more information.


This is an acronym for ‘Calling Line Identification Presentation’. Please see ‘Caller ID’ for more information.


CMOS is short for "Complimentary Metal Oxide Semiconductor". A CMOS conductor is an electronic chip that converts photons to electrons for digital processing. CMOS are used to create images in Digital CCTV cameras, digital video cameras and digital cameras.



CND is an acronym for ‘Calling Number Delivery’. Please refer to ‘Caller ID’ for more information.


CNID is shorthand for ‘Calling Number Identification’. Please refer to ‘Caller ID’ for more information.

Computer Telephone Integration

Please see ‘CTI’ for more information.

Connection Cord

A Connection Cord is the lead that connects your wired headset to your telephone. They are specific to the manufacturer of your headset, and there are a large number of variations to deal with the numerous choice of telephones available. You can use one of our handy connectivity guides to help you find the right connection cord.


Sometimes referred to as ATC (Audio Tele-Conferencing), conferencing functionality allows a caller to call and include more than one party within a phone call.


CTI stands for ‘Computer Telephone Integration’. CTI is the shorthand for describing systems in which telephone and computer technology is integrated to work to together.


DDI (Direct Dial Inwards) allows operators to call extensions directly, without routing through a switchboard first. Using DDI, a business is able to offer personalised telephone numbers for specific members of its staff, without the need for physical PBX lines for each connection.


DECT stands for 'Digital Enhanced Cordless Telecommunications'. Please see Digital Enhanced Cordless Telecommunications.


Dynamic Host Configuration Protocol Or “DHCP” is a Standardized protocol used on IP networks for dynamically distributing network configuration parameters, such as IP addresses for interfaces and services.


Digital Enhanced Cordless Telecommunications

Digital Enhanced Cordless Telecommunications is a digital communication standard which allows cordless telecommunication equipment to gain access to a fixed telecommunication network. At it's most basic level, it allows your cordless telephone or headset to use your telephone line.

Digital Signal Processing

Digital Signal Processing is a process where sounds, such as voice and audio, are digitalised in order that that they can be manipulated before being outputted.

DSS (Direct Station Select)

A method of using a button or softkey on a telephone station (such as a PBX extension) to select another specific extension or station to communicate with.


DN means ‘Direct Number’. This is a specific number assigned to any particular calling point (a department or individual, for example), negating caller interaction with a switchboard.


DND is shorthand for ‘Do Not Disturb’. When switched on, this phone setting will mute or redirect calls to a different, selected terminal.


DNR stands for Dynamic Noise Reduction. DNR removes unwanted background noise and mobile interference to ensure a high quality call.


This is a portable device that typically plugs into a parallel, or USB, port. Dongles grant access to wireless broadband or the use of protected software.


The DPNSS – or ‘Digital Private Network Signalling System’ – protocol is a private networking standard which provides access to all of a telephone system’s features across multiple PBXs in a single private network.


DPT is short for "Digital Proprietary Telephone". This is a telephone designed for use with a specific system or manufacture.


DSP is an acronym of 'Digital Signal Processing'. Please see Digital Signal Processing for for information.


This is an acronym for ‘Direct Station Select’. When pushed, this button will directly dial the number which has been assigned to it.


DTMF– or ‘Dual Tone Multi-frequency’ – refers to signals which are sent to other telecommunication devices (such as a switchboard) when buttons on a telephone are pushed. In the UK, the most common DTMF is ‘Touch-Tone’.

Dual Mode

Dual Mode refers to Mitel telephones being able to support both SIP and MiNET Protocols. This makes the phones more versatile.


Duplex refers the ability for two connected parties to be able to talk simultaneously. Both parties can transmit at the same time. In a conference call for example, both parties can talk at the same time without it affecting the quality of a call. When this is not possible, this is referred to as simplex.

DXDP (Digital eXtra Device Port)

DXDP is short for Digital eXtra Device Port. The DXDP allows you to add a second digital telephone to increase your system capacity without the need for additional circuit modules, jacks or wiring.

Dynamic Noise Reduction

"Dynamic Noise Reduction" or "DNR" is an unpatented technology that allows up to 10db of noise reduction from any audio signal.

Ear Cushion

An Ear Cushion is the soft cushion that sits between the headset earpad and your ear. These are usually either made of soft foam or soft leather. They come in many shapes such as circular and triangular, as well a doughnut shaped.


EHS is an acronym for 'Electronic Hook Switch'. Please see Electronic Hook Switch for more information.

Electronic Hook Switch

Electronic Hook Switch is a cable used to connect a telephone to the base unit of a cordless telephone. This cable allows users to remotely answer the telephone if they are away from their desks. It replaces the slightly cruder handset lifter.


FXO Port

FXO stands for "Foreign eXchange Office". FXO and FSX are the name of ports used by Analogue telephone lines. AN FXO interface is the port that receives the analogue line.

FXS Port

FXS stands for "Foreign eXchange Subscriber". FSX and FXO are the name of ports used by Analogue telephone lines. An FSX interface is the port that delivers the analogue line to the subscriber.


In regards to telecommunications, an ‘extension’ is simply the name given to each additional telephone set connected to one, single line.


GAP is short for "Generic Access Profile". GAP compatibility allows handsets the be registered with GAP compatible base stations and will allow you to make and receive calls. Other telephony functions may be limited and mixing manufactures is not recommended.

Gigabit Ethernet

Gigabit Ethernet describes the rate of transfer of frames / data at a speed of 1,000,000,000 bits per second as defined by the IEEE 802.3-2008 standard


GSM Stands for "Global System for Mobile Communications". GSM was developed to as a replacement for first generation (1G) analog cellular networks.

HAC Handset

HAC means ‘Hearing Aid Compatible’. HAC handsets (and other HAC technologies) do not interfere with hearing aids worn by anyone in close proximity – non-HAC models will often cause humming or whining noises in the ears of hearing aid wearers.

Handset lifter

A handset lifter is a device that sits on your telephone directly below the handset. This device connects to the base unit of a cordless telephone and when activated by the headset, it will lift the handset of the telephone so that your call is answered and transferred to the headset.


Hardphones are conventional telephone sets, which do not comprise additional software. Also see ‘Softphone’.

HD Voice

HD Voice is the trademark name for Plantronics Wideband audio. Please see Wideband.


HDSP Stands for "High Definition Sound Performance". HDSP is a Siemens invention that enables you to make Wideband calls over the internet (VoIP) when using a Siemens Gigaset handset.

Headset Port

A headset port is a dedicated socket on your telephone to which you can connect a telephone headset. Please use our helpful buyers guide to telephone headsets.


HFA or HiPath Feature Access operating mode combines the advantages of an IP based work station with the comprehensive feature set of an HiPath communications platform. HFA workpoints are connected to the LAN which is connected to a PBX by a gateway. By changing the phone software, a switch from HFA to SIP is possible.


HFAB is short hand for “Hands Free Answer Back”. This allows a speakerphone user to talk to an internal caller without lifting the handset. It can also used to monitor a room.


HyperText Markup Language (HTML) is the main language for displaying code on to your web browser as a user friendly web page.

Hybrid System

To learn about hybrid business telephone systems, contact us

Icon Buttons (Global)

Icon Buttons are soft and hard keys on your phone that have had the TEXT replaced with images. So instead of saying "Headset" there is an image of a headset. This is becoming more common as manufacturers, keen to sell in different countries, homogenize the manufacture of their products for these different markets, and reduce costs.


IP, which stands for 'Internet Protocol', manages the transfer of packets of data between IP address and is usually associated with TCP.


iPAQ refers to a Pocket PC and personal digital assistant as first termed by Compaq.


To learn about IPBX business telephone systems, please contact us


Internet Protocol Security (IPsec) is a protocol designed to enable secure IP communications by encrypting each IP packet of a communication session.

Ingress Protection (IP Rating)

Products that have an IP rating will be able to operate in hazardous environments and will be protected against, depending on the IP rating, the intrusion of solid objects such as hands, fingers, accidental contact, dust and water in enclosed electrical enclosures.

Here are a few examples:
IP54 Protected from water spray from any direction
IP65 Protected from low pressure water jets in any direction
IP66 Protected from high pressure water jets in any direction
IP67 Protected against immersion up to 1metre in depth
IP68 Protected against long term immersion up to a specific pressure


"IVR" is short for Interactive Voice Response. IVR is a technology that allows a computer to interact with humans though the use of voice and DTMF tones in via a keyboard. In telecommunications, IVR enables enables customer to interact with a company's host system via speech recognition or by a keypad, after which services can be inquired about through the IVR dialogue. IVR systems can respond with pre-recorded or dynamically generated audio to assist users of how to proceed.


ISDN stands for “Integrated Services for Digital Network”. This is a set of communication standards for simultaneous digital transmission of voice, video, data, and other network services over the traditional circuits of the public switched telephone network.


A jog dial is a type of knob, ring, wheel, or dial which allows the user to shuttle or “jog” through media such as directories, call lists etc.

Key System

To learn about key systems, please contact us


KSU is shorthand for ‘key system unit’ (also simply known a ‘key system’), a form of telephone system which is not connected to a PBX.


LAN is shorthand for Local Area Network. LAN is a computer network which allows computers in a small area to be interlinked E.g. Office building, school, computer laboratory.


LCD stands for 'Liquid Crystal Display'. This is a flat panel display that uses the modulation property of liquid crystals with light.


Light weight Directory Access Protocol or LDAP is an application protocol that lets you access a directory server and all the information stored there.


A telephone ‘line’ refers to a wire that carries telephone and telegraph signals.


"LIM" is short hand for "Line Interface Module. It is a device that allows you to add analog lines to a Mitel IP Phone.


"MEMS" stands for Micro Electro Mechanical System. MEMS is a technology of microscopic devices, particularly those with moving parts. MEMS are made up of components between 1 and 100 micrometers in size.


Microsoft Teams

Microsoft Teams is a unified communication and collaboration platform that combines persistent workplace chat, video meetings, file storage, and application integration.


MIMO, in networking, stands for Multiple-Input Multiple-Output, MIMO is a wireless technology that uses multiple transmitters and receivers to transfer more data at the same time. All wireless devices with 802.11n support MIMO.


MIDI or "Musical Instrument Digital Interface" is a file format without audio signal or media. Instead it holds information about musical note like pitch , intensity, volume and vibrato.

Microsoft Lync

Microsoft Lync is an instant messaging client used with Microsoft Lync Servers. There are many USB headset on the market that are Microsoft Lync optimised, and will benefit from additional features if used on a Microsoft Lync optimised servers and software.

Microsoft Office Communicator

Microsoft Office Communicator is the former name for 'Microsoft Lync'. See Microsoft Lync for more information.


MiNET is a proprietary protocol from Mitel that carries keystroke information from a telephone to a control server mainly used on Mitel IP telephones.


MOC is an acronym of 'Microsoft Office Communicator' which is now known as 'Microsoft Lync'.

Modem Port

A modem port allows quick and convenient connection when sharing your telephone line with a computer.


This stands for Music on Hold.


Monaural is used to describe a headset with one ear piece.


An MP3 or "MPEG-1 Audio Layer 3" is file format for loosely compressed storage of audio data.


MU-MIMO stands for "Multi-User, Multiple Input, Multiple Output". MU-MIMO was created to support environments where multiple users are trying to access a wireless network simultaneously. MU-MIMO is sometimes referred to as Next-Gen AC or AC Wave 2. Standards older that 802.11ac (including 802.11b, g and n) do not support MU-MIMO

Music on Hold

Music on hold (MOH) refers to music played to callers while they are on hold, or in a telephone queue. The music fills the silence the caller would otherwise be subjected to.


MWI or 'Message Waiting Indicator' refers to an LED light which informs the user he has one or more messages waiting on his phone or network.


NC is an abbreviation of 'Noise Cancelling'. Please see Noise Cancelling for more information.


Neckband refers to the position headset is worn when in use. The neckband wearing style is worn around the neck.


NFC stands for "Near Field Communication". NFC is a set of standards for smartphones and similar devices to establish radio communication with each other. These connections are established by simply touching them together or bringing them into proximity, usually no more than a few inches.


Noise Cancelling

Noise Cancelling refers to the microphone used on a device, usually a headset. These Noise Cancelling microphones cut out the background noise in your location, which helps you be heard more easily when having a conversation over the phone.


NIB stands for "Natural Interaction Behavior" and enables face to face communication in noisy environment, without the use of an external communication radio

Off-hook Dialling

Should a phone provide off-hook dialling only, this means the operator will only be able to input and call a number should the handset be lifted.

Omni Directional Microphone

Omni-Directional Microphones can pick up sound virtually from any direction. This design can be useful when a device needs to pick ambient sound or is used in an environment where the speaker is moving. This is in contrast to a Uni-Directional microphone which can only pick up sound from a specific side or direction of the microphone.

One-touch Dialling

This feature allows frequently called numbers to be dialled with the simple push of one, pre-assigned button.

On-hook Dialling

This feature allows operators to input, and call, a number without lifting the handset of their telephone.


To learn about PBX business telephone systems, please contact us


A PDA is a 'personal digital assistant' which is a mobile electronic personal data manager.


PeakStop is Jabra's trademark name for "Acoustic Shock Protection". See Acoustic Shock Protection for more info.


PFT stands for “Power Failure Transfer Port”. When activated in the event of a commercial power failure or a low-voltage battery, PFT supplies power to equipment via the central office trunk.


PKM stands for Programmable Key Module. This is a module that can be added to a telephone to add additional functionality such as a large number of programmable keys to be used as shortcuts.

Plain Old Telephone Service

Please see ‘POTS’ for more information.


PMR is short for Private Mobile Radio. PMRs are field radio communications systems which use portable, mobile, base station and dispatch console radios.


PNR is short for "Passive Noise Reduction". A PNR headset blocks harmful noise from damaging your hearing.

PoE & PoE+

PoE or 'Power over Ethernet' refers to electrical devices being able to receive electrical power from an ethernet cable at the same time as receiving data. Can be useful in reducing the amount of cabling required around the office.
PoE provides 15.4W of power per device (IEEE 802.3at-2003 Standard)
PoE+ provides 25.5W of power per device (IEEE 802.3at-2009 Standard)


In regards to telecommunications, a ‘port’ is a specific place - usually a socket - through which one device can be connected to another.


‘POTS’ is an acronym for ‘Plain Old Telephone Service’. POTS are the low speed analogue telephone systems which continue to be used in many home settings, as well as by some small businesses.


"PPE" is short for Personal Protective Equipment and refers to clothing, helmets, googles and other garments or equipment designed to protect the wearer from injury in hazardous or dangerous environments.

Proprietary IP

Proprietary IP telephones use a language specifically written by a phone manufacturer to use on its branded Cloud PBX. The advantage of Proprietary IP is that it is generally considered to have more features than it's open source counterpart Session Internet Protocol


The public switched telephone network (PSTN) is the total of the worlds circuit based telephone network, allowing anyone in the world to connect to another. At its core, it is almost all digital, but it includes mobile as well as fixed telephones.


PSU is short hand for 'Power Supply Unit', which is the power block required on certain products to power the unit. There is a large number of products on the market that do not require these, as they can use 'Power over Ethernet' instead where phone is powered by a cat 5 cable withing the local infrastructure.


"PTZ" stands for "Pan Tilt and Zoom Camera" and is a is a camera that is capable of remote directional and zoom control.


"PTT" Is short for Push To Talk. PTT is a common feature on 2 way radios


QD stands for ‘Quick Disconnect’. Please see ‘Quick Disconnect’ for more information.


QoS in networking stands for "Quality of Service" and refers to technology that manages data traffic to reduce packet loss, latency and jitter of the network.


Quick Disconnect

Quick Disconnect is a plug that connect a wired headset to it's connection lead. they are a identical flat plugs that simply click into each other.


RADIUS stands for ‘Remote Authentication Dial-In User Service’. Please see ‘Remote Dialling’ for more information.


Pushing this button will see the last number dialled from a telephone, redialled.

Remote Dialling

Also referred to as RADIUS (Remote Authentication Dial-In User Service), this protocol allows external servers to communicate with a business’s central sever, to request access to information, systems and/or services hosted on said central server.

Remote Voicemail Pickup

This functionality allows individuals to access voicemail messages they may receive while absent from their home/work environment, from other locations. Remote voicemail access may, or may not be, via a RADIUS.


Please refer to ‘Auto Dial’.


This Shared Call Appearance (SCA) service allows a user to have several devices for the same contact number and services are shared on several phones and endpoints.


SCCP is an acronym for Skinny Client Control Protocol. SCCP is a Cisco proprietary standard for terminal control for use with VoIP. SCCP was first developed by the Selsius Corporation. The term "Skinny" refers to fact that SCCP is a simple and uncomplicated protocol that requires relatively little computer processing


Simplex refers to communication in one direction only. One device will transmit, while the other listens. On a handsfree phone for example, if both parties try to talk at the time, the line will go quiet, because the phone is unable to transmit simultaneously. To do this, you will need a Duplex device.


SIP is an acronym of 'Session Initiation Protocol' which is a communication protocol for sending voice and video over IP networks.

SFB or Microsoft Skype for Business

SFB is short for "Skype For Business". Skype for Business was formally know as Microsoft Lync (ML). "SFB" is a UC (Unified Communications) Platform that integrates common channels of business communications such as Instant messaging (IM), VoIP (Voice Over Internet Protocol), FTP, Web conferencing, Voice Mail (VM) and E-mail.


SNMP or "Simple Network Management Protocol" is an internet standard protocol for managing devices on IP networks. Common devices that support SNMP are modem racks, switches, severs, telephones, routers and printers.


SLT is short for "Single Line Telephone"


SMART is short for "Smart Monitoring And Reporting Technology". SMART is a monitoring system that detects and reports on various indicators of drive reliability, SMART technology enable anticipation of hardware failures.


SNR is short for Single Number Rating, which is a value used for comparing the level of Noise Attenuation offered by ear defenders. The SNR value allows you to quickly compare the attenuation level offered by an ear defender. You simply substract the SNR value from the average noise level recorded in Decibels (dB) to get your "working" accoustic pressure. For example:
Noise Level recorded: 110dB
SNR Rating: 32
Acoustic Pressure: 110 - 32 = 78dB. Anything under 85dB is considered safe.


A softphone is a software-based telephone, most often utilising a PC and headset, which enables emulation of a Hardphone.

Sound Card

A sound card is hardware that can be added to a PC. These sometimes come with a PC, or can be added at a later date. They allow your Computer to handle sound more effectively, as well as letting other devices, such as headset, to connect to your PC.


Soundguard is the trademark name for the Plantronics 'Acoustic Shock Protection' technology. Please see 'Acoustic Shock Protection' for more information.

SOLAS Chapter II-2

SOLAS stands for "Safety of Lives At Sea" and is a maritime treaty which requires signatory flag states to ensure that ships flagged by them comply with the minimum safety standards in construction, equipment and operation. For ships constructed on or after 1st July 2014 a minimum of two two-way portable radios for each fire party for fire fighters communication must be carried on board. The two radio units must be explosive and or intrinsically safe


A telephone comprising a microphone and loudspeaker, allowing hands-free verbal exchanges.


Speakfocus is a Sennheiser technology which focuses on the user's voice to give clear sound even in noisy conditions.

Speed Calling

This telephone feature allows operators to dial from a list of frequently used numbers using a one or two-digit pre-assigned number, to make dialling more efficient.

Switch Box

A switch box is a device that sits between a telephone and a headset. It is very similar to an amplifier except it doesn't boost the audio signal. It does allow a user to easily switch between a headset and a handset though.

Talk Time

Talk time is the amount of time a telephone (or related accessory) can be used before its battery is exhausted and requires recharging.


TAPI stands for 'Telephony Application Programming Interface'. Please see Telephony Application Programming Interface for more information.


Transmission Control Protocol (TCP) is one of the core protocols of IPa>. It checks for missing packets of data and the order of the packets between programs to ensure reliability.


TDM or Time Division multiplexing are digital telephones without a LAN interface. They are connected to PABX by PoE and the phone hardware is not compatible to SIP and HFA phone hardware.

Telephony Application Programming Interface

Telephony Application Programming Interface is a Microsoft Application Interface that allows computer telephony integration and enables your PC to use telephone services such as dialling and answering calls.


TMA or "Telephone Management Application" is a windows based software package used by Gai-Tronics products that allows you to remotely monitor the heath status of your SMART Telephones, program their functions and log and report on their stats - all over a standard telephone line.


Please refer to ‘DTMF’.


UC stands for unified communications. UC is the incorporation of real time communications services, this would include IP telephony, video conferencing, data sharing, instant messaging etc.


UHF Stands for “Ultra High Frequencies”. UHF is International Telecommunication Union designated range of radio frequency electromagnetic waves between 300 Mhz and 3GHz (3,000 Mhz), also known as the decimetre band or decimetre wave.

Ultra-Noise Cancelling

Ultra-Noise Cancelling microphones are simply more powerful 'Noise Cancelling' microphones. Please see 'Noise Cancelling' for more info.

Uni Directional

A Uni-Directional Microphone can only pick up sound with high gain from a specific side or direction of the microphone. When using a Uni-Directional microphone the user must speak directly into the correct side or their voice will not be picked up. This is in contrast to Onmi-Directional Microphones which pick up sound equally from all directions of the microphone.


USB is an industry standard for a plug/connection between a PC and electronic device. This standard allows a connection which enables data communication and power to be transferred between the 2 devices. USB stands for 'Universal Serial Bus'.

There are a few different types of USB connectors. The most common are USB Type-A which is found on most PC's and interfaces and has been around for many years. This is now being replaced by USB Type-C. These have a reversible plug, so it doesn't matter which way round you plug it in. More importantly, they can carry more power than the 5v achieved by USB Type-A, but are also closely intertwined with USB3.1, offering greater down speeds of up to 10Gbps (double the speed of USB3.0).,


VDSL stands for “Very-High-Bit-Rate Digital Subscriber Line”. VDSL is a data communications technology that provides faster data transfer than ADSL over telephone lines. VDSL offers speeds of up to 52Mbit/s downstream and 16Mbit/s upstream. VDSL2 is the 2nd generation system and can exceed 100 Mbit/s simultaneously in both upstream and downstream directions.


VHF Stands for “Very high Frequency”. VHF is the International Telecommunication Union designated range of radio frequency electromagnetic waves from 30 MHz to 300 Mhz. Frequencies below VHF and denoted “HF” or High frequency, and frequencies higher than VHF are known as “UHF” or Ultra High Frequencies.

Virtual PBX

A virtual PBX (Private Branch Exchange) is a private telephone switchboard, hosted and managed by a telephone service provider on behalf of a business.

Virtual Receptionist

Please see ‘Auto Attendant’

Video Stitching

Video Stitching is the process of combining multiple images with overlapping fields of view to produce a segmented panarama or HD image.

Voice Broadcasting

Please see ‘Auto Dial’.

Voice Clarity

Voice Clarity is the trademark name for Sennheiser HD Wideband audio. Please see Wideband.

Voice over Internet Protocol

This protocol allows human voices to be transmitted over the internet (in digital form) or other networks (in audible form), instead of via standard telephone lines.

Voice Tube

A voice tube is a usually clear open ended microphone extension that helps headset microphones better receive any speech from the user.


VoIP is an acronym for ‘Voice over Internet Protocol’. Please refer to ‘Voice over Internet Protocol’ for more information.


VOX is short for Voice operated exchange. This is a switch that operates when a sound over a certain level is detected. VOX is often used in Private Mobile radios to enable Handsfree features.


A virtual private network (VPN) creates a private network connection across a public network, such as the Internet. This enables a PC or telephone to send and receive data across an open public network as if it was connected to a private network with all the security benefits.


WAV or " Waveform Audio File" is a file format by Microsoft and IBM for uncompressed or lossless compressed storage of audio data. It is also been known as a "WAVE" file


WAP or " Wireless Access Point", also know as AP "Access Point" and "Hot spots," is a networking hardware device that W-Fi enabled devices can connect to.


WDS stands for Wireless Distribution System. A WDS is a system enabling the wireless interconnection of access points in a network. It allows for a wireless network to be expanded by using multiple access points without the traditional requirement for a wired link to connect them together.


Wideband is an audio technology that allows audio telephony to be broadcast over a greater frequency range, which results in a clearer more natural sound. Wideband is accepted to cover the frequency range of 50–7,000 Hz.


Windsafe is the registered name for the Sennheiser microphone anti wind noise technology which helps sound quality when speaking outside in blustery conditions.


Windsmart is the registered name for the Plantronics advanced anti wind noise technology with 3 layers of wind protection.


A WLAN or “Wireless Local Area Network” links two or more devices use some wireless distribution method, and usually providing a connection through an access point to the wider Internet. Most modern WLANs are based on IEEE 802.11 standards, marketed under the Wi-Fi brand name.


The Whisper Off-Hook Call Announce (WOHCA) feature allows you to call via intercom to another 7400 Series phone user who is engaged on a private call. The facility enables you to provide information to the user on your exchange, without disturbing the other caller.


XDP stands for Extra Device Port, XDP allows for other devices to be connected to certain types of telephones.


Extensible Markup Language (XML) is a computer language that defines a set of rules for handling data in a format that is readable to both computers and humans.


A Y cable is a headset splitter used for training purposes. A Y cable allows 2 headsets to be connected to one telephone. The Y cable will usually have a little switch in it that allows either one or both people to speak on the line at once. Both headsets can hear of course.

Zero Touch Provisioning

When using certain IP/SIP phones, Zero Touch Provisioning can be used to quickly and easily get full configuration without having to manually provision the phone to your network.

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