Jargon Buster

We have tried to make our website as clear as possible.  However the telephone world is full of technical information and confusing terminology.  Click on an item below for a brief description.

ACD – Automatic Call Distributor

The mechanism by which telephone calls are distributed to ‘agents’, typically within a call centre environment. A software application that runs on a PBX to provide call centre functionality.

ADSL – Asynchronous Digital Subscriber Line

Allows data transmission along standard telephone wires. ADSL has a higher data download speed than it has upload, ranging from 256k/s to 24mb/s.

ASR – Automated Speech Recognition

The ASR function allows the caller to speak simple commands into the auto attendant system (iAB) to progress the call, e.g. “YES” or “NO”, “one”, “two”, ”three” etc.

BSC – Base Station Controller

A device (or software) that controls the BTSs within a GSM network. Within Private Mobile Networks one BSC can control and manage the signalling and voice channels for 100 BTSs.

BTS – Base Tranceiver Station

A GSM antenna – this is responsible for transmitting and receiving the specific GSM frequency for a particular network. This could be in the form of a picocell for Private Mobile Networks but would also apply, on a much larger scale with a large GSM mast, to Vodafone, Orange etc.

Call Management

A general term used to describe the process of determining the manner in which telephone calls are handled and their ultimate destination. Usually used with respect to incoming calls, i.e. calls received by an organisation.

CLI – Calling Line Identity

CLI is a telephone service that transmits a caller’s number to the called party’s telephone. Where available, CLI can also provide a name associated with the calling telephone number.

CoDec – Coder Decoder

Codecs encode a data stream or signal for transmission, storage or encryption, or decode it for viewing or editing.

CPE – Customer Premise Equipment

Usually refers to a telephony system (PBX) that physically exists at the customer’s premises. The alternative is a hosted service.

CRM – Customer Relationship Management

A business philosophy that involves anticipating, understanding and responding to customer needs whilst maximising profits.

DDI – Direct Dial Inbound

A service whereby a call made to a DDI number can be routed directly to an internal extension without intervention by a switchboard operator.

DECT – Digital Enhanced Cordless Telecommunications

DECT (Digital Enhanced Cordless Telecommunications) is a digital wireless telephone technology, DECT uses time division multiple access (TDMA) to transmit radio signals to phones. Whereas GSM is optimized for mobile travel over large areas, DECT is designed especially for a smaller area with a large number of users, such as in cities and corporate complexes. A user can have a telephone equipped for both GSM and DECT (this is known as a dual-mode phone) and they can operate seamlessly.

DPNSS – Digital Private Network Signalling System

A standard protocol used to connect PBXs together (including systems from different manufacturers) to form a large corporate telephone system.

DSL – Digital Subscriber Line

Allows data transmission along standard telephone wires. Using a higher frequency than normal voice traffic, DSL comes in two flavours. ADSL (Asynchronous DSL) has a higher data download speed than it has upload, ranging from 256k/s to 24mb/s. SDSL (Synchronous DSL) is used less frequently and allows the same transmission speed for both upload and download.

DTMF Tones – Dual Tone Multi-Frequency

The term used to describe the process used in push button telephones for transmitting information based on which key is pressed. Each key generates a sound using a different pair of frequencies.

EDGE – Enhanced Data rates for GSM Evolution

EDGE is a digital mobile phone technology that allows increased data transmission rates and improved data transmission reliability. EDGE can be used for any packet switched application, such as an internet connection.

FMC – Fixed Mobile Convergence

FMC marries together the best aspects of fixed and mobile services and simultaneously alleviates the negative associations of disparate telephony services. FMC means access to traditional fixed-line services on the mobile handset, making internal and external communications more efficient, and employees more productive and responsive.

FXO Gateway

An FXO (Foreign eXchange Office) is the interface that connects to the Public Switched Telephone Network’s (PSTN) central office. In an IP environment FXO is the interface on the gateway that allows connectivity between VOIP systems and specifically analog devices such as POTS handsets or fax machines or a PSTN phone line.


In a communications network, a network node equipped for interfacing with another network that uses different protocols.

GPRS – General Packet Radio Service

General Packet Radio Services (GPRS) is a packet-based wireless communication service that promises data rates from 56 up to 114 Kbps and continuous connection to the Internet for mobile phone and computer users. The higher data rates allow users to take part in video conferences and interact with multimedia Web sites and similar applications using mobile handheld devices as well as notebook computers. GPRS is based on Global System for Mobile (GSM) communication and complements existing services such circuit-switched cellular phone connections and the Short Message Service (SMS).

GSM Network

Global System for Mobile communications – the standard for digital cellular phone services across the UK, Europe and many other countries.

Hardware Platform

The physical electronic system comprising one or more computers (usually referred to as servers) on which software is run to provide the service or solution required.

Hosted Service

In the context of telephony, the term refers to the provision of a telephony service where the functions normally fulfilled by a PBX on the customers premises (see CPE) are provided by a system housed remotely, owned and managed by a service provider. The hosted service will be shared between a large number of customers.

Hybrid Architectures

A solution comprising a mix of different technologies, e.g. PBXs (based on TDM) and IP-PBXs (based on the Internet Protocol).

IMEI – International Mobile Equipment Identity

IMEI is a number unique to every GSM mobile phone. The IMEI number is used by the GSM network to identify valid devices and therefore can be used to stop a stolen, or blocked, phone from accessing the network. It is usually found printed on the phone underneath the battery or accessed by dialing *#06# on your mobile phone.

IMSI – International Mobile Subscriber Identity

IMSI is a unique number associated with all GSM network mobile phone users. It is stored in the SIM card inside the phone and is sent by the phone to the network.


A telephone switching system that uses a signalling system based on the Internet Protocol as opposed to traditional PBXs that are based on a Time Division Multiplex (TDM) protocol.

IP Telephony

A telephone system that operates over a data network using the Internet Protocol.

IPEI – International Personal Equipment Identity

The IPEI (International Portable Equipment Identity) is a unique 13-digit serial number, embedded into every DECT phone.

ISDN – Integrated Services Digital Network

The key feature of the ISDN is that it integrates speech and data on the same lines, adding features that were not available in the ‘classic’ telephone system.

IVR – Interactive Voice Response

A system where a caller uses their telephone keypad to respond to computer generated voice prompts. The simplest form of IVR system is an Auto Attendant where the caller’s keypad choices determine the ultimate destination of their call. In the more complex form of IVR, the telephone system is connected to one or more external database. A typical example here is telephone banking, where callers are able to find out the balance in their account or even transfer funds from one account to another.

Macro Network

A Macro network usually refers to the larger national (or global) GSM networks such as Vodafone, O2, etc. A micro network is a smaller, private GSM network.

MSC – Mobile Switching Centre

A device (or software) that controls the BSCs and other components with a cellular network. It has overall responsibility for cell handover and end-to-end connection of calls.

MPLS – Multi Protocol Label Switching

A mechanism that allows different types of traffic along a data network. Along with other transmission mechanisms, it delivers packets of information between nodes on a network, sharing bandwidth with other network users and protocols.

Multi-Vendor Architectures

A solution that incorporates functional elements from different manufacturers, e.g. a corporate telephony system comprising inter-connected PBXs from different vendors.

PBX – Private Branch eXchange

The switching system within an organisation that connects calls between internal telephones or between internal telephones and external phones connected via the Public Switched Telephone Network. Also referred to as a PABX (Private Automatic Branch eXchange) but, since all present day switching systems are automatic, the terms are now used interchangeably.

PoE – Power over Ethernet

Power over Ethernet technology is a system to transmit electrical power, along with data, to remote devices over standard twisted-pair cable in an Ethernet network. This technology is useful for powering IP telephones, wireless LAN access points and other appliances where it would be inconvenient, expensive or infeasible to have a separate power supply.

POTS – Plain Old Telephone System

POTS is a term which describes the voice-grade telephone service that remains the basic form of residential and small business service connection to the telephone network in most parts of the world. Sometimes known as Post Office Telephone System.

PMR – Private Mobile Radio

PMR stands for Private (or professional) Mobile Radiocommunication. In parallel to public mobile communications, usually known under the GSM standard in Europe, PMR systems address mobile communication needs of professional users including police, civil protection, customs, utilities, transports,airports, private security.

PSTN – Public Switched Telephone Network

Public Switched Telephone Network, refers to the international telephone system based on copper wires carrying analog voice data. This is in contrast to newer telephone networks base on digital technologies, such as ISDN, IP, ATM and FDDI.

Telephone service carried by the PSTN is often called plain old telephone service (POTS).


An ISDN-based European signalling protocol standard similar to the UK-based DPNSS standard.

QoS – Quality of Service

Quality of Service is the ability to provide different priority to different applications, users, or data flows, or to guarantee a certain level of performance to a data flow.

SALT – Speech Application Language Tags

Speech Application Language Tags – similar to VoiceXML but used to add speech/telephony capabilities to web-based applications.

Servers / Preconfigured Servers

A computer system that, typically, runs some software to perform a specific task or set of tasks. See also Hardware Platform.

SDSL – Synchronous Digital Subscriber Line

Allows data transmission along standard telephone wires. SDSL allows the same transmission speed for both upload and download.

SIM – Subscriber Identity Module

SIM cards securely store the service-subscriber key or IMSI (see above) used to identify a subscriber. The use of SIM cards is mandatory in GSM devices.

SIP – Session Initiation Protocol

SIP is a signalling protocol used for establishing sessions in an IP network. A session could be a simple two-way telephone call or it could be a collaborative multi-media conference session.

SIP Handsets

A SIP handset is a device that uses SIP as its method of transmitting and receiving voice traffic, such as a SNOM phone.

SMS – Short Message Service

SMS is a communications protocol allowing the interchange of short text messages (up to 160 characters) between mobile telephone devices.

SMSC – Short Message Service Center

SMSC is a network element in the mobile telephone network which delivers SMS messages. It is one of the components of the PMN system enabling the sending and receiving of SMS messages.

SRST – Survivable Remote Site Telephony

A backup solution where a call is maintained at a remote site even when the PBX at the main site is not available.


In the context of telephony systems, sometimes used to mean a PBX or IP-PBX (see separate entries).

TDM – Time Division Multiplex

A technique for handling a number of voice or data signals over a common medium, e.g. a single wire, by sending a small portion of each signal, one after the other, in quick succession.

TTS – Text-to-Speech

A technology that converts textual information, held in digital form, into computer-synthesised speech used, i.e. to inform callers of their current balance in telephone banking systems.

Unified Messaging

A solution that brings together different types of electronic messages (e.g. voice, fax, video, email) into a single mailbox or inbox, making it more convenient for the user to access.

URL – Uniform Resource Locator

The address of a page on a website, e.g. www.teleware.com is the URL of the home page on the TeleWare website.

Wrap Up

A period of time at the end of a telephone call for the ‘agent’ to write notes, complete paperwork, compose themselves, etc before being presented with another call. This is commonly used in call centre environments.

Virtual Team

In this context, virtual is used to describe a geographically dispersed group of people who, nevertheless, work together as a team.

Voice Continuity

The concept of ensuring that a telephone call can be made and received under any circumstance and is immune to abnormal conditions.

VoiceXML Services

Services based on the Voice eXtensible Markup Language. VoiceXML is a standard computer software language used to develop voice-user interfaces based around advanced techniques such as voice recognition and text-to-speech.

VoIP – Voice over IP

VoIP (Voice over Internet Protocol) is the transmission of voice traffic over IP-based networks. This could be publically, over the internet or privately over a managed IP network.

VPN – Virtual Private Network

A process whereby software is used to create what appears as a private network running over a public network. VPNs are typically used to extend an organisations internal computer network to off-site locations such as branch offices and to home-based employees.

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