AC15
A signalling system used for linking two pieces of telecommunications equipment (e.g. two telephone systems) over a distance. See also DC5.

Account Code
A way of attaching a "tag" to a call record. This might be used to indicate that the call is to be charged to a particular account or to indicate the outcome of a call (a sale was made, a brochure requested etc.) Call Management systems can then produce reports listing all calls with the same account codes. Account codes can be attached to incoming and outgoing calls, and it can be made mandatory for an extension user to enter an account code before a call is made.

ACD
Automatic Call Distribution. Allows all incoming calls to be distributed equally amongst a group of people. Typically used in a call centre where operators (agents) log in to make or receive calls. ACD systems provide facilities for monitoring the agents performance and the performance of the Call Centre as a whole. An incoming call will be automatically routed to the first available agent, whether that is an agent who has been free the longest, or an agent that has just become free.

ADSL
Asymmetric Digital Subscriber Line. High bandwidth network connection for faster data transfer (connection generally allowing more bandwidth downloading than uploading). Increases efficiency and reduces costs. See Broadband.

Alpha Tagging
The assignment of an alpha-numeric name to a facility. For example when called by an extension your phone can display the name of the caller rather than the extension number. When an incoming DDI call is received a name can be shown which relates to the number that was dialled, enabling one person to answer calls in a variety of different ways, e.g. in the names of different companies.

Analogue Device
A device that can be attached to an ordinary analogue telephone line, such as a telephone, fax machine, cordless phone, answering machine, modem etc.

ARS
Automatic Route Selection. A technique where the telephone system looks at the digits being dialled to make an outside call and automatically routes the call via an alternate route. Best possible cost efficiencies for outgoing or inter site calls. See also LCR.

Auto-Attendant
A voicemail feature that allows callers to be automatically transferred to extensions or departments by dialling digits. A tone dialling phone is normally required to do this.

Bandwidth
The speed at which a circuit can carry data. The more bandwidth, the faster the data transfer, the lower the costs.

Basic Rate
Abbreviated to BRI (basic rate interface) or ISDN2. An ISDN circuit providing 2 x 64 kbit/sec bearer channels for use by data or speech and one 16 kbit/sec control channel. Two independent calls can be carried at the same time on one BRI circuit.

Battery Back-up
See UPS.

Bell
See Loud Ringing Bell.

BLF
Busy Lamp Field. Visual indication of the status of lines or extensions through LEDs.

Bluetooth
Wireless communication protocol for several devices to communicate on a common format. Your mobile phone could transfer data to your keyset, PDA, PC or Printer etc. Similar to infra-red.

BRI
See Basic Rate.

Broadband
BT's brand of Asymmetric Digital Subscriber Line see ADSL.

Bulletin Board
An electronic version of a notice board. Users can access the bulletin board to obtain information. When applied to voicemail systems it indicates a system of menus that allow the caller to navigate to the information he wants, for example to find out what films are showing at a cinema.

Call Barring
The prevention of calls to certain destinations, e.g. overseas calls or calls to premium rate numbers may be barred.

Call Forwarding
Also known as call diversion. By dialling a code an extension user can divert incoming calls to another destination. The destination may be another extension, a group of extensions, the operator, or an external number, for example a mobile phone. Different types of diversion are usually possible, e.g. Diversion of All calls, Diversion on Busy, Diversion on no reply.

Call Logging
Data recorded about calls made or received through a telephone system. This data can then be used for reporting. See Call Management. See also Station Message Detail Recording.

Call Management
The use of specialist software to analyse and report on call records which are output from a telephone system and recorded on computer disk. The results can identify misuse, allocate costs to departments and verify the adequacy of resources.

Call Park
A call can be parked by one user and then retrieved by another. Particularly useful when loudspeaker announcements are made, e.g. "Telephone call. Joe Smith dial 811". If Joe goes to any phone and dials 811 he will get the call that has been parked there for him.

Carrier Telephone
Service provider eg. BT, Cable and Wireless, NTL etc.

Cat 5
Abbreviation for Category 5. Strictly speaking this is a specification for the transmission performance of a data cable. However it is commonly used to describe a building cabling system that allows the user to easily route voice and data circuits to any wall socket. It is designed to be network independent and to allow different computer and telephone systems to co-exist on the same cabling.

CCU
Central Control Unit. The box or cabinet housing the central equipment that controls the telephone system.

Centrex A generic name for a feature offered by some Public Network Operators. Users have individual direct exchange lines but calls between users are free of charge and calls can be transferred between users. A limited set of features is provided to give something that approximates to a virtual telephone system. BT brands for this service are Featureline and Featurenet.

CLI
Calling Line Identity is the capture of the caller's number. There are two types of CLI, a Network CLI is used by network operators to identify the source of the call. It is available whether or not the caller is ex-directory but is never passed on to the called party. The user CLI is passed on to the called party, providing that the caller has not withheld it. By default it is the same as the network CLI but can be changed by the caller's equipment. For example in a firm a salesman might want his direct dial number to go out but the Managing Director might want his secretary's number to go out when he makes a call. CLI is used for the "1471" service where you dial 1471 to find out who called and can also be used to display the number on a phone or computer. CLI is not available on some networks (particularly from overseas) and is usually an optional feature from the network provider (the subscriber has to pay to receive it).

CLIP
Calling Line Identity Presentation. A service that provides a called party with the Calling Line ID of the caller. Usually a paid-for option. See also Connected Line Presentation.

CLIR
Calling Line Identification Restriction. Would stop your own CLI being presented to the called party.

COLP
Connected Line Presentation. A service which provides the caller with the identity of the person he has connected to. For example you may dial 01234 567890 but that number may be diverted to another. COLP will provide you with the identity of the person you have actually connected to. The identity is typically the telephone number of the connected party. This is a paid-for service from the network provider and compatible equipment is required to make use of it.

Conferencing
The joining together of more than two telephone users in a single call. Typically a call will be established between two persons, one will then hold the call, call a third party and then press a button to join all three parties in one call.

Contact Centre
A progression of the call centre merging customer calls with other media such as internet and email in conjunction with CRM applications. A unified approach to customer contact improving customer service levels leading to increased customer acquisition, satisfaction and retention.

Convergence
The merging of voice and data hardware solutions such as the server based PBX. More efficiency and cost benefits becoming available through convergence. In addition Voice switched Over IP is driven by convergent technology.

CPS Carrier Pre-selection.
Carrier Pre-Selection uses network access technology, so voice 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 point of entry (the local exchange) to the public voice network.

CRM
Customer Relationship Management. A software application to deliver a single view of the customer.

CTI
Computer and Telephony Integration. The exchange of information between computers and telephone systems eg. when a call comes in the telephone could pass to the computer the telephone number of the person calling. This can deliver "Screen Popping" - the presentation of database information based on an incoming caller's CLI. Information is commonly passed between telephone and computer systems using an Application Program Interface (API) of which the two most common are TAPI (Telephony API) and TSAPI (Telephony System API). CTI is commonly divided into First Party CTI, where a telephone and a computer are directly connected, and Third Party CTI, where the telephone system and the computer network communicate through a telephony server, with no direct physical connection between the telephone and the user's computer.

Custom Service Mode
Used in voicemail to indicate a service where the caller hears a menu of choices from which he can choose by pressing buttons on his phone. These choices might transfer him to an extension, group of extensions, or the operator, enable him to leave a message or listen to information, or may offer him other menus.

DC5
A signalling system used to communicate between two adjacent pieces of telecommunications equipment, for example between a telephone system and a router or multiplexer or between two co-located telephone systems. For communication over longer distances DC5 can be converted to AC15. See also AC15

DDI
Direct Dialling Inwards enabling outside callers to call directly to a user's extension. Normally available on ISDN lines. A company may have 10 lines and 100 telephone numbers. When any of the telephone numbers are dialled by an incoming caller the call is put on to any line that is free. At the same time the dialled number is passed to the telephone system. The phone system uses this to route the call to the intended recipient. Typically used to provide direct dial numbers for extension users, fax machines, departments or groups of extensions. This is much more efficient than the older method of using different sets of lines for different numbers because all lines can be used for all numbers and so less lines need to be rented overall to provide the same level of service. Also decreases the number of calls that have to be answered and transferred by an operator.

DECT
Digital Enhanced Cordless Telephony. A technology that provides greater clarity and smaller handsets for cordless phones. There is a common standard called GAP (General Access Protocol) that allows handsets and base stations from different manufacturers to work together.

Delayed Ringing
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.

Dial-up
A communications link that connects a terminal and a computer via the Public Switched Telephone Network (PSTN).

DISA
Direct Inward Station Access. Provides callers with single-digit access to extensions or ring groups.

DPNSS
Digital Private Network Signaling System. Developed in the early 1980s, a protocol to support connection between telecom equipment from different vendors digital equipment. See also QSIG.

DSS
Direct Station Selector. A unit that fits alongside a telephone to turn it into an operator console. Typically containing a large number of programmable buttons that can be used to call and to indicate the status of extensions (stations).

DSL
Similar to ADSL, but allows the same amount of bandwidth in both directions.

E+M
Another name for DC5

Extension Lock
A facility to prevent unauthorised phone use. An extension can be locked by entering a code and unlocked by entering a password. When locked the phone is subject to call barring, perhaps restricting it to internal and emergency service calls only.

GAP
General Access Protocol - see DECT.

Group Ringing
A group of extensions is rung by dialling a number. The group may be set as a ring group, in which case all of 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.

GSM
Global Satellite Mobile. Improved call security and quality.

GUI
Graphical User Interface. A program interface, such as Microsoft Windows, that takes advantage of the computer's graphics capabilities to make the program easier to use. Well-designed graphical user interfaces can free the user from learning complex command languages. A GUI will usually feature basic components such as a pointing device (mouse or trackball) to allow you to select objects, icons (small pictures) that represent commands, a desktop area, where icons are grouped, and a menu for the user to select a command from.

Hunt Groups
A means of finding a free extension to take a call. Calls are directed to a Hunt Group and will search for a free extension to take the call. Various hunting types are available, First Free or Terminal Hunting will search for the first free extension in the group, so this person gets most of the calls. Circular or UCD (Uniform Call Distribution) Hunting will share calls equally over the group.

IP
Internet Protocol. Access to standard global communications protocol.

IP Address
A series of characters that uniquely identifies the terminal equipment which is the origin or destination of data being transmitted.

ISP
Internet Service Provider. Allows you to connect to the Internet.

ISDN
The Integrated Services Digital Network. An internationally agreed method of providing digital communication over the Public Switched Telephone Network (PSTN). Enables the benefits of DDI, CLI, Trunk-to-Trunk Transfer and faster data transfer. See also Basic Rate (ISDN2) and Primary Rate (ISDN30).

ISDN2
See Basic Rate.

ISDN30
See Primary Rate.

Keyphone
A telephone for use with a particular make and model of telephone system which incorporates features allowing it to communicate with the telephone system and display information, typically by means of lights, buttons and visual displays.

Keysystem
A telephone system designed for all extensions to answer incoming calls. The distribution of all incoming calls across a business or team.

LAN
Local Area Network. Enables PCs to communicate data between each other and common devices or servers also connected to the network.

LCD
Liquid Crystal Display. A display panel found on many phones capable of showing text prompts or messages.

LED
Light Emitting Diode. A semi-conductor device used as an indicator lamp. Typically these are incorporated into buttons allowing visual indication of calls, voicemail messages and status of other lines and extensions - see BLF.

LCR
Least Cost Routing. A technique where the telephone system modifies the digits dialled by a user making an outside call in order to route the call via a low-cost carrier. Typically the routing decision is based on what number has been dialled and it is often possible to have several carriers configured on the same telephone system to take advantage of the cheapest route to any destination. See also Automatic Route Selection (ARS). Typically ARS incorporates and builds on the capabilities of LCR.

Least Cost Routing
See LCR.

Live Call Screening
A facility available on some voicemail systems which allows someone who has diverted his calls to voicemail to listen to a caller leaving a message and pick up the call if he wants to.

Loud Ringing Bell
An audio warning device to alert someone that a call is ringing. It may simply be an extension bell to a telephone or it could be a set of bells around the building so that anyone can pick up the incoming call.

Mailbox
A reference to the location where voicemail messages for a particular user are stored.

MAPI
Microsoft Application Protocol Interface. Protocol designed to ensure all Microsoft applications can communicate with other applications in a standard and documented format.

Meter Pulse Detection (MPD)
A BT service for their analogue lines, to allow a subscriber to accurately establish the charge of a telephone call. To a subscriber, it was a Meter Pulse received by monitoring equipment down their telephone line. To BT, it was a Charge Unit recorded on the subscriber's meter in the local BT exchange. During a call, the first pulse would be transmitted the moment the call connected. Subsequent pulses would be transmitted at time intervals thereafter, the interval depending upon the telephone number dialled and the time of day. Hence, the more expensive the call, the shorter the time interval (and therefore the more Meter Pulses), and vice-versa. No new supply or additional supply of Meter Pulsing has been provided since the end of December 1998.

MSN
Multiple Subscriber Numbering. An optional feature of ISDN2 lines allowing up to 10 telephone numbers to be assigned to a single line so that devices connected to that line can be called individually. Can be used to produce a limited version of DDI.

Music on Hold
An audio signal that is played to a caller on hold to reassure him that he has not been cut off. Typically music, it may be interspersed with advertising messages or could be simply a reassuring beep played every few seconds.

Network
The equipment and transmission facilities for communication between computer systems.

Night Service
Most telephone systems have at least two operating modes, Day Service and Night Service. These are typically used to route incoming calls to a different destination and to apply call barring to prevent unauthorised use of the phones by security or cleaning staff.

Overflow Group
See Delayed Ringing.

Parallel Port
Port in a PC used for the connection of external equipment such as a printer, scanner etc. See also serial port.

Patch panel
Cabling connection point. This is typically the part of a structured network cabling system (cat 5) that enables switching of services either voice or data to RJ45 sockets.

PBX / PABX
Private Branch Exchange / Private Automated Branch Exchange. Allows central control of incoming call via a single operator.

PMS
Property Management System. Hotel / Motel "Front of House" software package.

POT
Plain Ordinary Telephone. Used to distinguish an ordinary analogue telephone from a keyphone. Also known as an SLT (single line telephone).

PRI
Primary Rate Interface. See Primary Rate.

Primary Rate
An ISDN circuit providing (in Europe) up to 30 x 64 kbit/sec bearer channels for use by data or speech and two 16 kbit/sec control channels. Up to 30 independent calls can be carried at the same time on one Primary Rate.

PSTN
Public Switched Telephone Network. Everyone connected to standard communications platform.

Pulse Dialling Also known as LD (loop-disconnect) dialling. A method of dialling where the telephone is alternately disconnected and connected to signal to the exchange. For example if a digit 5 is dialled this could be signalled by sending 5 disconnection pulses. The frequency and length of the pulses and the number of pulses for each digit can vary from country to country. This dialling method is now mostly superseded by tone dialling.

QSIG
Q signalling standard. A standard dial up protocol designed to give feature transparency between systems at different sites across the PSTN. Allows products from different vendors to work together. See also DPNSS.

Router
Routes data traffic. Can be used to connect LANs together or as a single connection point between a LAN and an ISP.

SBUS
The digital connection from a telephone system to a PC. Provides the ability to utilise ISDN lines for voice and data traffic.

Screen Popping
The initialising and presentation of database information selected using the CLI. Reduces the time spent searching for customer service history etc.

Serial Port
Port in a PC used for the connection of external equipment such as an external modem. Also used for connection of call-logging, CTI, etc. See also parallel port.

SLT
Single Line Telephone. See POT.

SMDR
Station Message Detail Recording. See Call Logging.

Switch
See PBX / PABX.

TAPI
Telephony Application Program Interface. A standard devised by Microsoft Corporation for communication between a computer terminal (workstation) and a telephone extension. There are several versions of the TAPI standard and various options within the standard so it should not be assumed that all the features of one TAPI compliant device will be available on any other TAPI compliant device. See also TSAPI.

TCP / IP
Transmission Control Protocol / Internet Protocol. Set of layered protocols that enable shared applications among PCs in a high speed communications environment.

TDM
Time Division Multiplexing. Traditional telephony technology employed to connect two parties in a call via a PBX.

Tone Dialling
Also known as MF (multi-frequency) or DTMF (dual tone multi-frequency). A dialling method which generates audio tones when digits are dialled. These tones are sent down the line and can be detected by telephone systems or other devices.

Trunk
A telephone exchange line to receive and make calls.

Trunk-to-Trunk Transfer
A facility which allows an incoming call received on one line to be transferred to someone on another line, i.e. both callers are external to the telephone system. Typical uses include transferring an incoming caller to someone's mobile phone.

TSAPI
Telephony System Application Program Interface. A standard devised by Novell Corporation for communication between a network server and a telephone exchange. Because it is working at a system level this offers more flexibility than TAPI but is also more complex to implement.
Two-Way Record A facility of voicemail systems and answering machines which allows both sides of a telephone conversation to be recorded for later playback.

Unified Messaging
A messaging platform that allows management of voice, fax and email from a single user interface (PC). Improves efficiency as all messages are presented from the one place to the user.

UPS
Uninterruptible Power Supply. Provides continuous power source to the telephone system in the event of a mains power fail. Also referred to as Battery Back-up.

UTP
Unshielded Twisted Pair. A type of cable. Commonly (and imprecisely) used to differentiate from computer cables using co-axial cable such as 10 Base 2, Thin Ethernet, Thinnet, Thick Ethernet, Thin Ethernet or IBM Twinax.

Voicemail
A voicemail system typically provides a central "answering machine" for users of a telephone system. The user diverts his calls to the voicemail system, which will play a personalised message to a caller and allow him to leave a message for the extension user. Most voicemail systems also provide options for routing callers to departments or extensions and for giving out information to callers.

VOIP
Voice Over Internet Protocol. Allows voice calls to be switched over any data carrying network reducing fixed infrastructure costs.

VPN
Virtual Private Network. Provides users with inter site communications, which could be implemented over fixed circuit connections but also via dial up connection. This has many cost benefits to the user as the need for fixed line voice circuits may be removed.

WAN
Wide Area Network. Improves cost and efficiency as PC users in different sites may all access the same information as if they were all connected locally on the one local area network.

WAP
Wireless Access Protocol. A means of accessing the Internet using a mobile phone.

WOC
Windows Operator Console. PC based operator terminal. Allows the user to see the status of lines and extensions on their PC screen and answer and transfer calls with the click of a mouse.

XDP
eXtra Device Port - an analogue port in the back of some keysets, which can be used as either a 'double' of the existing extension number (ie for an analogue DECT) or as a totally different extension number (ie for an analogue modem.)