Understanding Phone System Jargon

The world of business telephone systems is awash with acronyms and jargon. To this end, we have produced this exhaustive list of all the terms that you might come across whilst viewing our site or researching your telephone system.

ACD	Automatic Call Distribution
	A system which distributes large volumes of incoming telephone calls uniformly from a queue to agent positions. The calls may be distributed to the agents on a priority basis via a variety of definable criteria
ACI	Advanced Connectivity Interface
ALI	Analogue Link Interface
API	Application Programmers Interface
	A software specification encompassing instructions and information to enable the writing of applications which are independent of the equipment they are being used with.
APNSS	Analogue Private Network Signalling System
	An analogue version of DPNSS.
Applet	Small application (software)
ASSF	Analogue System Supported Featurephone
ATM	Asynchronous Transfer Mode
	A transmission and switching technique capable of supporting voice, video and data (multimedia) communications. It is unique in that each piece of information is addressed and is of the same length. This allows very high-speed communications
BHCA	Busy Hour Call Attempts
BRAIF	Basic Rate Access Interface
	Realitis DX/iSDX interface card for access to basic rate ISDN trunks and terminals.
Break in	The ability to dial directly into a local PBX and then across a private network of PBX systems from an external exchange line.
Break out	The ability to dial across a private network and to then access an exchange line at a suitable terminal PBX in order to enable the call to be charged at the "local rate"
BRI	Basic Rate Interface
	Access to the ISDN service at 144Kbps provided as two B data channels of 64Kbps and one D control channel of 16Kbps (2B+D).
Busy hour	The continuous 60 minute period during any measurable period when the calls handled by the system is at maximum.
CAI	Common Air interface
	An interface for CT2 digital cordless communications, developed in the UK and adopted by the DTI and as a European standard. CAI allows the interworking of CT2 handsets and base stations from different vendors.
Call centre	A Call centre is a business function, usually comprising a set of ACD agent groups, dedicated to servicing transactions over the telephone.
CallPath	A standard for CTI closely, but not exclusively, associated with IBM. Realitis ACD supports CallPath
Callscan	Callscan is the product name of the management information system for the Realitis ACD. Callscan has 2 models available, single-user and multi-user
CAS	Channel Associated Signalling
	A transmission protocol in which data for each channel is passed in specific time-slots.
CAT	Computer Assisted Telephony
	See CTI
CCS	Common Channel Signalling
	The use of a dedicated channel for the transfer of signalling information relating to a number of other channels.
CCS	Cent Call Seconds
	A unit of traffic intensity equal to the average number of calls per hour assuming a mean holding time of 100 seconds. Therefore, 36 CCS are equivalent to 1 erlang. Also known as Hundred Call Seconds (HCS).
CDS	Caller Display Service
	BT's method of delivering calling line identity into the home and small businesses.
CIL	Call Information Logging
	Automatic recording of telephone calls made on a PBX system with details of call (e.g. date, time, extension number, and duration), for use in call accounting or billing.
CIT	Computer Integrated Telephony
	See CTI
Class of service	Class of service defines the telephone facilities available to extension users.
CLI	Calling Line Identification
	Information passed through the public or private telephone network which provides an indication of the calling party's telephone number to the PBX and which can be displayed at any system specific display terminal on Realitis DX.
Conference call	A call including more than two parties. A conference may be initiated by an agent or from another source.
CSTA	Computer Supported Telecommunications Applications
	A standard for the protocols used across the link between computer and PBX. Originated in Europe by ECMA. Also used as a general term for the CTI area. See CTI
CT2	Cordless Telephone (second generation)
	A world-wide standard for digital cordless telephony. As established in the UK, CT2 uses 4MHz of channel frequency between 864.150 MHz and 868.05MHz.
CTI	Computer Telephone Integration
	The ability to inter-work the call centre or ACD with other computer systems. This interrelationship between computers and telephony has many names including CSTA, CAT, CIT and iCAT
DASS	Digital Access Signalling System
	A UK-only public network standard developed by BT and its suppliers. Current version is DASS2
DCC	Delta Channel Controller
	A device to control the internal Realitis DX/iSDX CCS highway.
DDI	Direct Dial Inwards
	Enables the Realitis DX to receive dialled numbers directly from the trunk interface.
DLI	Digital Link Interface
	A digital trunk interface on Realitis DX supporting signalling protocols such as DPNSS, DASS2 and ISDN primary rate.
DN	Directory Number
	The number listed to be dialled by customers for connection to a particular answering point. Each agent position or telephone within a network may have a unique directory number.
DND	Do Not Disturb
Dongle	A software protection device.
DPNSS	Digital Private Network Signalling System
	A private networking standard developed by BT and other PBX suppliers which allows full feature access to be provided between PBXs in private networks.
DSS	Direct Station Select
	A button on a terminal which can be used to directly dial a person or extension associated with that button.
DTMF	Dual Tone Multifrequency
	Signalling which is the basis for the operation of pushbutton telephone sets. Dialled numbers are transmitted as tones rather than electronic pulses. This is particularly useful for access to supplementary services (e.g. voice mail and banking)
ECMA	A European association for standardising information and communications systems.
EMC	Electromagnetic Compatibility
	A measure of a system's ability to operate without its efficiency being impaired by interference from other systems, and without affecting the operation of other systems.
ETS	European Telecommunications Standard
	A standard published by ETSI. N.B. I-ETS is an Interim European Telecoms Standard.
ETSI	European Telecommunications Standards Institute
	The body responsible for the development of telecommunication standards that will be ratified by the EU for use within the European Community
EuroISDN	A name for ISDN as defined by the relevant European ETSI standards
FTP	File Transfer Protocol
	Simple message based protocol used to exchange file information between UNIX-based computer systems.
Gateway	A method of interpreting differing protocols between disparate computer and/or telephone systems is often required. This conversation and interpretation can be performed on a gateway. Gateways are common to support CTI and some CTI functions for the Realitis DX such as iCAT and CallPath are implemented as gateways.
HCS	Hundred Call Seconds
	See CCS.
Hybrid	Term generally used for a business communications system providing PBX and/or key system functionality. The term is also used for any device which provides more than one mode of working.
iCAT	Integrated Computer Assisted Telephony
	A range of computer telephone interface (CTI) products supported by Realitis ACD.
IPX/SPX	Protocol used by Novell Netware
ISB	Inter Shelf Bus
	The ISB carries control signals within Realitis DX.
ISDN	Integrated Services Digital Network
	A fully digital communications facility providing transmission of voice, data and video across public or private networks. Access to the service is at basic rate (see BRI) or primary rate (see PRI).
ISO	International Standards Organisation
	Technical agency of the United Nations concerned with international standardisation in a broad range of industries.
ITU	International Telecoms Union
	Telecoms agency of the United Nations concerned with international standardisation in a broad range of industries.
IVR	Interactive Voice Response
	Systems which enable callers to conduct transactions, store or retrieve information. The interface may be by voice recognition and/or DTMF.
Keysystem workingGroup	Terminals can be members of more than one group. Each terminal can have its own key and lamp layout. Unused keys are available for user definition. Keys and lamps can be configured to give access to incoming trunks.
LAN	Local Area Network
	A network designed to provide facilities for user communications within a defined building or plant and which does not necessarily use public service facilities or standards.
Leased line	A dedicated circuit, supplied by the PTT or other licensed operator, which permanently connects two or more user locations and is for the sole use of the subscriber.
MAPI	Messaging Application Programming Interface
	A Microsoft Windows interface.
MDF	Main Distribution Frame
	A wiring arrangement that connects outside lines on one side and internal lines from exchange equipment on the other.
MDSC	Modular Digital Shelf Controller
	Part of the Realitis DX processor subsystem.
Media card	The media card is used for memory backup on Realitis DX systems.
MIS	Management Information System
	The software and hardware required to manage the ACD operation. The MIS for Realitis ACD is Callscan. Callscan provides a number of real time, sophisticated displays, giving 'real time' information required to manage the ACD operation or call centre effectively. The MIS also stores call records to provide historical data in report form.
MMI	Man Machine Interface
	Any procedure which allows a human operator to access and operate a system.
Modem	A device that modulates and demodulates signals transmitted over communications facilities. It is used to allow digital signals to be sent over analogue lines.
MSIF	Modular Shelf Interface
	Used to control communications between the processor and telephony interfaces on Realitis DX.
MTBF	Mean Time Between Failure
	The period of time that a system or device can be expected to work before a disabling fault occurs.
MTTR	Mean Time To Repair
	The average time required to return a faulty device or system to service.
Multiline group working	Each terminal can be a member of only one multiline group.
	All the terminals in that group must have the same key and lamp layout.
Multimedia	A combination of two or more media (i.e. voice, data, still image, video)
multiplexer	A device that enables more than one signal to be sent simultaneously over one physical channel.
Network	A network provides users with communications links between different geographical locations
Night service	The period outside normal working hours when the call centre is either directing or overflowing calls to another answering point.
NMS	Network Management System
	A system which monitors networked PBXs or keysystems and provides the network manager with information on traffic levels and congestion, fault management and call accounting.
Node	An intelligent routing point on the telephone network, for example an ACD or PBX.
NT1	First customer premise device on a two-wire ISDN circuit coming in from the ISDN central office.
OCA	Open communications architecture
	Siemens's strategy for the future, providing a framework for existing and future Siemens Telecommunications products. OCA frees the customer from the constraints of proprietary architectures and, by harnessing the power of technology, unlocks the full potential of telecommunications.
ODBC	Open Database Connectivity
	A Microsoft standard which allows databases created by various relational and non-relational database programs to be accessed by a common interface.
OSI	Open Systems Interconnection.
	ISO's reference model for a seven-layer network architecture used for the definition of network protocol standards
Packet switching	A data communications technique where the data is broken down into fixed-length units (packets) which are then transmitted to their destination through the fastest route. The receiving station ensures that all units are received and are in proper sequence before forwarding the data to an addressee.
PBX	Private Branch Exchange
	A telephone system where incoming calls are mainly answered by an attendant who offers those calls to the required extension. (May also be called PABX).
PCMCIA	Personal computer memory card international association
Point and click	A process whereby the user moves their mouse until the pointer on the screen reaches the desired button or control on the screen. The mouse is clicked to initiate the activity associated with that button or control
POT	Plain Ordinary Telephone
PRI	Primary Rate Interface
	Access to the ISDN service at 2.048Mbps in Europe (known as 30B+D) and 1.544Mbps in the US, Japan and Canada (known as 23B+D).
Private circuits	Dedicated telecommunications links between nodes.
Private network	A communication network designed and operated for the exclusive use of a particular organisation or group of organisations.
PSTN	Public Switched Telephone Network
	The public telephone system, including telephone, local and trunk lines, and exchanges.
PSU	Power Supply Unit
PTO	Public Telecommunications Operator
	An organisation licensed to run a public telecommunications system.
PTT	Postal, Telegraph and Telephone Organisation
	A government department responsible for and with authority over postal, telegraph and telephone operations.
PWA	Printed Wired Assembly
QSIG	A PBX networking protocol produced by ECMA in line with ETSI and ITU ISDN recommendations.
RAID	Redundant Array of Inexpensive Disks
	Several disk drives are placed into a single housing. Data is written over the disk drives in such a way that if one or more of the drives are lost, none of the data will be lost.
RISC	Reduced Instruction Set Computer
RNR	Ring no reply
SBC	Screen Based Console
	The computer based Realitis DX attendant console incorporating interactive on-screen directory system.
SCSA	Signal Computing System Architecture
	An architecture which describes how both hardware and software building blocks work together. It is a common set of standards that telecommunications systems manufacturers can use to create computer telephony systems.
SCSI	Small Computer System Interface
Service level	The service level is a definition of perceived customer satisfaction. Service level is usually measured as the percentage of calls answered successfully within a predefined period of ringing.
Short code dialling	The ability to make calls from a predetermined list by using a simple abbreviated instruction.
SPI	Service Providers Interface
SQL	Structured Query Language
	Database language invented by IBM and used for creating, maintaining and viewing database
TA	Terminal Adapter
	Allows existing non-ISDN terminals to operate on ISDN lines. It provides conversion between a non ISDN terminal device and the ISDN user/network interface
Tandem	An exchange used to switch network traffic between other nodes.
TAC	Trunk Access Class
TAPI	Telephony Applications Programmers Interface
	A standard for CTI developed by Microsoft and Intel associated with PC based computer systems. It is an open standard which permits the direct control of a telephone from a windows based application.
TCP/IP	Transport Control Protocol/Internet Protocol
TE1	Terminal Equipment Type 1
	ISDN-compatible terminals. A TE1 can be an ISDN telephone, a personal computer capable of working with ISDN, a video-phone etc any device that can attach to and work with ISDN.
TELNET	Network terminal emulation protocol. Simple protocol to allow programs to exchange ASCII and control characters over network interfaces, as though the data were being produced/displayed by a normal terminal.
Terminal	Any device capable of sending or receiving information over a communication channel.
Tie Line	A permanent communications link between 2 or more PBXs provided by a PTT/PTO.
TJF	Test Jack Frame
	See MDF
Trunk	An individual circuit, provided by either a public network operator or via a private network capable of carrying an individual telephone call (either incoming or outgoing).
Trunk performance	A measurement of the efficiency and utilisation of a particular trunk.
TS	Trunk Select
	A button on a terminal which can be pressed to answer incoming trunk calls on that button.
TSAPI	Telephony Services Applications Programmers Interface
	The equivalent of TAPI in a Novell environment where control of the telephone is initiated over the LAN rather than by direct connection to the telephone.
UPI	Universal Peripheral Interface
	Part of the Realitis DX processor subsystem
UPI	Universal Peripheral Interface
	Part of the Realitis DX processor subsystem
V Series	ITU recommendations covering data transmission over telephone circuits
V.24	Standard serial port (equivalent to RS-232C)
VAN	Value Added Network
	Network built using the communications offerings of traditional common carriers, but connected to computers that permit new types of telecoms tariffs to be offered.
Video-conferencing	Communication using systems which support image, voice and data transfer over digital circuits. Videoconferencing systems can take the form of large, dedicated units for group meetings or can be integrated with desktop PCs.
VIM	Vendor Independent Messaging
VIOCA	Visually Impaired Operator Console Attachment
Voice messaging system	Hardware and software products that operate with most PBX, hybrid or key systems allowing users to send, receive and redirect voice messages through office telephone systems and computers. Also called voice mail.
Voice processing system	Hardware and software products that encompass voice messaging, voice recognition, voice response and any applications that deal with the processing of voice communications.
Voice recognition	A system that translates human voice into computer commands. Also known as speech recognition.
Voice response system	A computer connected device that can selectively link sentences of stored words to create an appropriate spoken message.
VPN	Virtual Private Network
	The provision of facilities normally associated with a private telecoms network over the shared lines, exchanges, and switches of a public network.
X series	ITU recommendations covering data transmission over digital circuits. e.g. X.25, X.75