Telecommunications Glossary

AC15

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

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. A means of managing large volumes of calls. 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.

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 which 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. For example a user in London may dial the DDI number of someone in the Aberdeen Office. The phone system recognises that there is a tie-line to the Aberdeen office over which calls are free and automatically re-routes the call over the free circuit. See also LCR

Auto-Attendant

A voicemail feature that allows callers to be automatically transferred to extensions or departments by dialling digits.

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

All of our systems have internal batteries to retain programming in the event of a failure of the mains electricity supply, however the system will not operate without mains power. We can provide battery back-up power to keep the system working without mains power as an option.

BRI - see Basic Rate

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 cellphone. Different types of diversion are usually possible, e.g. Diversion of All calls, Diversion on Busy, Diversion on no reply.

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.

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 which 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 which 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. A number representing the originator of a call. 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 ID Presentation.

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.

CTI

Computer and Telephony Integration. The exchange of information between computers and telephone systems. For example, when a call comes in the telephone could pass to the computer the telephone number of the person calling. This could be used to perform a look-up in the customer database and display the caller's record before the call is answered. 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.

DDI

Direct Dialling In. 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.

DECT

Digital Enhanced Cordless Telephony. A technology which provides greater clarity and smaller handsets for cordless phones. There is a common standard called GAP (General Access Protocol) which 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.

DSS

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

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.

Hunting

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.

ISDN

The Integrated Services Digital Network. An internationally agreed method of providing digital communication over the Public Switched Telephone Network (PSTN). See also ISDN2 and 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.

LCD

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

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 rout to any destination. See also Automatic Route Selection (ARS). Typically ARS incorporates and builds on the capabilities of LCR. 

Least Cost Routing

see LCR

LED

Light Emitting Diode. A semi-conductor device used as an indicator lamp. Typically these are incorporated into buttons and show red or green.

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. 

MSN

Multiple Subscriber Numbering. An optional feature of ISDN2 lines allowing up to 10 telephone numbers to be assigned top 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.

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.

Parallel Port

In computing, a character is represented by a binary number (byte), typically made up of eight binary digits (bits). A parallel port is a connector where information is made available and can be read one whole character (or byte) at a time. See also serial port.

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.

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

A means of signalling between telephone systems using a 2 Mbit/sec digital link, allowing up to 30 simultaneous calls on one circuit.

Serial Port

In computing, a character is represented by a binary number (byte), typically made up of eight binary digits (bits). A serial port is a connector where information is made available and can be read one binary digit (or bit) at a time. Therefore 8 bits need to be read in order to obtain each character. See also parallel port.

SLT

See POT

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.

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 line connecting a telephone system to another telephone system or to the Public Switched Telephone Network (PSTN).

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.

Voice over IP (VoIP)

A method of transmitting speech using Internet Protocol (IP). IP is a method of  transmitting data that is used not only in the public Internet but also in private computer networks. The speech signal is digitised and transmitted over the network as data. At the receiving end it is turned back into analogue speech. 

Voicemail

A voicemail system typically provides 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.

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.

WAP

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

XDP

eXtra Device Port. A term used on the Panasonic KX-TD range of digital telephone systems. Each extension port on the system will support a digital keyphone and an analogue phone at the same time and on the same extension number. For example a keyphone will sit on the desk with a cordless phone alongside. Either can be used. They both have the same extension number. When XDP working is enabled in programming they become separate extensions with different numbers, allowing for example the user to be talking on the phone while using a modem to get his e-mail. When XDP is enabled separate sockets can be wired for the digital and the analogue ports, allowing the system size to be doubled. For example a 32 extension system could have 32 digital extensions as well as 32 analogue extensions, all independent of each other using XDP working.