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Telecoms Glossary

The following Glossary in no way covers all the new language and acronyms that are associated with VoIP technologies, but it may get you a step closer to understanding some of the jargon you may encounter.

Analog (analogue)

An analog system is considered to be the traditional telephone system, and it works by converting sounds or video signals into electrical vibrations so they can be transmitted or reproduced.

Analogue Telephone Adapter (ATA)

This allows you to use your existing, traditional handset even though you have a VoIP connection by converting your VoIP signal into a standard telephone signal.

Area Code

Usually a 3 digit number, found in front of a telephone number which provides Goegraphic representation or segregation of the line or user.



Asymmetric Digital Subscriber Line (ADSL)

A high-speed broadband Internet connection utilizing copper wire to transmit data over the phone lines between ADSL modems / routers. It has a faster download speed than upload speed, which makes it different from DSL connections.


The amount of time it takes a specific volume of data to be sent from one computer to another utilizing a certain connection. The higher the bandwidth, the faster data is accessible. Bandwidth is measured in bits per second.


The general term for any Internet connection that transmits and receives data at a rate of 100kbps or higher.

Call Forwarding

Call Forwarding allows you to re-direct or forward all calls to an alternate number. Calls can typically be forwarded to any other number - mobile, international, etc.

Call Waiting

Call Waiting is a service that allows you to receive more than 1 call at a time, but with the 2nd caller being put on hold with an alert tone being heard by the user and caller.

Caller Identification (ID)

Caller Identification, aka CLI is the activation and display number of the calling party. CLI allows you to see the number from which you are being called.


Capacity refers to the maximum load which a platform or system can function.

CDR Call Detail Record

Details about a specific call that includes duration, origination, destination, and billable information, as well as other pertinent information.


Circuit-switched is a type of network where a physical path is obtained and dedicated for a single connection between two points in the network, for the duration of the connection between these two points. Ordinary phone services are circuit-switched.

Class of Service

Class of Service


Normally used in reference to converting analog signals to digital or digital signals to analog. It can be used in conjunction with compression software to compress and decompress these signals to varying degrees.

Contention Ratio

Contention Ratio

Customer Premises Equipment (CPE)

Customer Premise Equipment (CPE) refers to telecommunications hardware devices located on the clients premises. This equipment might include Internet routers, VoIP gateways, telephones, etc. CPE can be owned by the provider or the customer.

Data Packet

All data transmitted over the Internet uses the same basic technology. When this data is transmitted, it is sent in blocks of digital data called packets.

DDI Direct Dialling Inward

A service that allows an enterprise to allocate individual phone numbers to each person within its PBX system.

DSL Digital Subscriber Line

Phone technology that allows a broadband internet digital connection to be carried over existing copper phone lines, while still allowing the phone service carry analog signals over the same line.

DTMF Dual Tone Multi-frequency

Also known as Touchtone, it is the signal generated when you press a telephone's touch keys that is sent to the telephone company. These signals are actually two tones of a specific frequency designed so that a voice cannot duplicate them. The ability for interactive telephone menus to work correctly across different networks and phone systems is due to the fact that DTMF tones are standardized and are uniquely linked to a number (and # or *) on the telephone keypad.


A VoIP gateway is a gateway device that uses Internet Protocols to transmit and receive voice communications (VoIP)

I-ECNS Licence

Individual ECNS Licence – The ECNS licence comes in two variants, Individual and Class. The Class Licence restricts the Licensee to a geographical area, whereas the Individual Licence enables the Licensee to operate countrywide. The ECNS licence allows the licensee to provide ECNS services to its customers.


Inter-Asterisk eXchange Protocol, (pronounced "eeks") (now commonly meaning IAX2)
An Asterisk communications protocol for setting up interactive user sessions (both audio and/or video) and supports any type of codec.


Independent Communications Authority of South Africa. This is the regulatory body responsible for oversight of the telecommunications industry.

Interconnect Agreement

An Interconnect Agreement is the process for physically connecting the networks of different carriers.

The charges which one telecommunications operator charges another for terminating calls on its network may be symmetric (operators pay equal amounts to each other) or asymmetric (one operator, usually the incumbent, pays less than the other operator).

The rates to interconnect providers is currently governed and dictated by ICASA.


The Internet is a global system of inter-connected computer networks that use the Internet protocol (TCP/IP) to serve several billion users.

Internet Protocol

The Internet Protocol (IP) is the method or protocol by which data is sent from one computer to another on the Internet.

Internet Service Provider (ISP)

An Internet service provider (ISP, also called Internet access provider) is a business or organization that offers users access to the Internet and related services.

IP Telephony (Internet Protocol telephony):

An IP telephone system uses packet-switched Voice over IP (VoIP), or Internet telephony, to transmit telephone calls over the Internet as opposed to the circuit-switched telephony used by the traditional Public Switched Telephone Network (PSTN). Also known as VoIP phone systems, IP telephone systems typically comprise a VoIP private branch exchange (an IP PBX) and desktop VoIP phones (IP Phones) that connect to a VoIP service provider via a Local Area Network (LAN).


As data load increases and decreases, routers on the Internet can create slightly different times that individual packets take to travel from one point to another point. This variation in time is known as jitter.

Kilo-bits per second (Kbps)

Kilobits per second (Kbps) is a unit of measurement for data transfer speeds


Latency is a measure of time delay experienced in a system, the precise definition of which depends on the system and the time being measured.

Local Area Network (LAN)

A LAN (local area network) supplies networking capability to a group of computers in close proximity to each other.

Mega-bits per second (Mbps)

Mbps stands for megabits per second and refers to the speed of data transfer.


Multi Protocol Label Switching

Number Portability

Number portability (NP) refers to the ability to transfer either an existing fixed-line or mobile telephone number assigned by a local exchange carrier (LEC) and reassign it to another carrier.


Point of Presence. A point-of-presence (POP) is an artificial demarcation point or interface point between communications entities


Point of Presence

PSTN Public Switched Telephone Service

The combination of local, long-distance and international carriers that make up the worldwide telephone network.

Public Switched Telephone Network (PSTN)

Traditional phone system that uses a copper wire network to carry analog voice data. Also called a ‘landline network.’


Quality of Service. A measure of the level of service quality provided by a telecommunications provider or device. If a router, for example, can provide QoS functionality, it can be programmed or tuned to deliver voice packets ahead of data packets and provide a better voice quality.


Quality of Service


A router is a device connected to at least two networks that determines the next network point to forward a packet to. The decision of which way to send each information packet is based on it's current understanding of the networks that it is connected to.

SIP Session Initiation Protocol

is a signaling protocol for Internet conferencing, telephony, and instant messaging. It is a request-response protocol, dealing with requests from clients and responses from servers. initiating an interactive user session.

SIP Session Initiation Protocol Trunking

is the use of VoIP to facilitate the connection of typically a PBX to the Internet, where the Internet replaces the conventional telephone trunk, allowing a business to communicate with traditional PSTN telephone subscribers worldwide by connecting to an ITSP (Internet Telephony Service Provider).


A softphone (software telephone) is an application program that enables voice over Internet Protocol (VoIP) telephone calls from computing devices such as Laptops and Smart Phones.


A network switch is a hardware device that joins multiple computers together.


A recognized standard for sending fax transmissions over an IP network in real time mode.


Value Added Network Services. A term used to refer to other alternative, telecommunications service providers that provide telephony services to the telecommunications market.

VoIP Voice over Internet Protocol

The transmission of voice over the Internet as digital packets rather than the traditional circuit-committed protocols of the PSTN.


Virtual Private Network


WiMAX is a telecommunications technology aimed at providing wireless data over long distances in a variety of ways, including point-to-point links and full mobile cellular type access. WiMAX allows a user, for example, to browse the Internet on a laptop computer without physically connecting the laptop to a wall jack.


References the transmission of information (data, voice etc) over electromagnetic waves rather than over a wire connection.