VoIP Definitions - An A-Z Guide

VoIP Home Phone Service

The A-Z of VoIP Definitions :

A- VoIP Definitions

ADSL (Asymmetric Digital Subscriber Line) – a form of data communications technology that allows fast data transmission over copper lines. The term ‘asymmetric’ refers to the fact that the data flow is greater in one direction than the other. This isn’t a problem for consumers who are mainly receiving data from the internet.

Analogue transmission - Every sound is in analogue format. Analogue transmission was a means of transmitting voice over a network in its ‘wave-form’. In early days this was passed through amplifiers as the sound faded over distances, though this also produced noise on the line. This has been largely replaced by digital transmission.

ASR (Answer Seizure Ratio) – a ratio that is used to assess the reliability of calls to a particular destination. It is calculated by taking the total number of calls answered to that destination/network (Answer) and dividing it by the total number of calls that were physically sent (Seizures) *100. Although many factors (such as the far end receiving person being out of the house) can distort this ratio, it gives a good indication of the effectiveness of links to that network or country.

ATM - Asynchronous Transfer Mode – a connection based relay network protocol, whereby data is encoded into small fixed-size cells, as opposed to variable sized packets used in IP networks. The connection between the two endpoints is made and confirmed before any data is sent.

Backbone - A general word used to describe the core of a network, ie the main trunk routes running between different points, from which all other smaller routes originate.

Bandwidth - Bandwidth is a term used to describe the rate or speed of data flow over a network. It is also used to refer to the physical capacity between two points.

BGP (Border Gateway Protocol) - is the key routing protocol of the Internet, which makes decisions on routing based on the path, network policies and rule-sets. It works by maintaining a database of IP networks on which it makes its routing decisions.

Broadband - A general term referring to bandwidth which is capable of handling a wide range of frequencies. In the case of ADSL, this is described as broadband over a telephone line via a modem. Find out more about broadband

CDR - Call Display Records are a set of information about a telephone call that can be stored and analysed by the Service Provider. They may contain information such as the time, calling party, number called, length of the call, etc. They form the basic data used by Service Providers to bill their customers, and can also be used to help analyse network performance.

CLI - Caller Line Identity (CLI) is the piece of information that displays on your telephone the number of the person calling. Some telephone systems are unable to pass this information. However, the majority of customers are now demanding that CLI is available as a requirement.

Compression - This is technology that ‘squeezes’ data together by removing any unused or inefficient portions, in order to minimize the bandwidth taken up when a call is sent to its destination. There are various forms of compression – it is generally regarded that the higher the compression ratio, ie how many times the data is squeezed, the more loss of quality occurs.

Codec - This is a device capable of performing Coding and Decoding on a data stream or signal. In the case of a VoIP call, the Codec will encode the call packets and then decode it at the other end in order that a stream of voice can be heard.

Digital transmission - A form of transmission where signals are converted into 1’s and 0’s in order to be sent over a network. This means there is less of a problem with noise on the line, and the transmission of the voice is more efficient than in an analogue network.

DTMF - Dual-Tone Multi-Frequency is a signaling type which is used for signaling over the line in the voice frequency band to the switching centre. In modern terms, it is known as Touch Tone, a form of dialing by pressing a series of numbers.

Echo cancellers – a device used to remove the echo found on a phone line as a result of delay. It can be the result of the length of the circuit being used for the call, or delay in the packets arriving at their destination in the case of VoIP. In effect, echo cancellers should be used on any long distance calls, or calls over IP or on mobile networks.

Endpoint - Any piece of equipment that sits on one end of a communication connection. For example, an endpoint may be a telephone, a PC, or a Media Gateway.

Ethernet - A broad name for the networking technology used between computers and other devices on the same Local Area Network (LAN). It has been standardized as the IEEE 802.3.

EGP (Exterior Gateway Protocol) – an early routing protocol for the internet which is a type called a path vector protocol. Border Gateway Protocol (BGP) has become the more accepted standard for routing traffic over the internet.

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