Glossary
A | B | C | D | E | F | G | H | I | J | K | L | M | N | O | P | Q | R | S | T | U | V | W | X | Y | Z
A
ACD
Automatic Call Distribution (i.e.: directing a call to the most appropriate call handler in the shortest possible time, attempting to ensure that the caller is satisfied, that incoming call queues are managed effectively and that the call handling resources are efficiently and effectively used).
ADSL
Asymmetric Digital Subscriber Line (ADSL) is a form of DSL, a data communications technology that enables faster data transmission over copper telephone lines. ADSL provides high downstream and low upstream.
ADSL provides high downstream and low upstream.
ADSL2
ADSL2 extends the capability of basic ADSL, both in terms of speed and features.
ADSL MAX
ADSL Max is not a new type of ADSL. It is a marketing phrase that is been used for a new range of products from BT.
ADSL PLUS
Unlike standard ADSL, which is a contented service (2:1, 5:1, 10:1, 20:1 and 50:1), ADSL PLUS is a uncontended service i.e. 1:1.
AES
Advanced Encryption Standard (i.e.: a symmetric 128-bit block cipher data encryption algorithm).
ALG
Application Layer Gateway. A component that provides VoIP-specific firewall capabilities.
Analogue
An analogue signal is a variable signal in terms of time and amplitude.
Analogue line
A PSTN line.
ATA
Analogue Telephone Adapter. An ATA is a device which acts as a hardware interface between a PSTN analogue telephone system and a digital network or IP telephony service.
Auto-attendant
A voicemail feature that allows callers to be automatically transferred to extensions or departments by dialling digits.
B
Bandwidth
In digital systems bandwidth is data rate (e.g.: of channel capacity or network throughput) measured in bits or kilobytes per second.
Battery Back-up
See UPS.
Breakout
When making a VoIP call, when the receiver is on a non-VoIP line, the call must breakout of the VoIP network, typically via an ITSP.
BRI
Basic Rate Interface ISDN service. See ISDN2.
Broadband
Broadband is a general term that is used to describe high bandwidth internet services. It actually applies to any service that has a 256 kbps or faster download speed.
C
Call Barring
The prevention of calls to certain destinations, e.g. overseas calls or calls to premium rate numbers.
CDR
Call Detail Record.
Call Forwarding
Also known as call diversion. By dialling a code, a user can divert incoming calls to another destination. The destination may be another extension, a group of extensions, the operator, or an external number e.g. a mobile phone. Different types of diversion are usually possible, e.g. Diversion of All calls, Diversion on Busy, Diversion on no reply.
Call Hunting
A calling feature for inbound calls that will “roll past” a busy signal or try multiple numbers until the call is answered.
Call Logging
Data recorded about calls made or received through a telephone system.
Call Management
The use of specialist software to analyse and report on call records which are output from a telephone system.
Call Park
A call can be parked by one user and then retrieved by another.
CAT5
An Ethernet cable standard. CAT5 cables contain 4 twisted pairs of copper wire, support 100 Mbps bandwidth and is limited to a maximum recommended run lengths of 100m (328 feet).
CAT5e
An enhanced version of CAT5 variation that supports increased bandwidth. CAT5e cabling is backward-compatible with standard CAT5 cabling.
CAT6
A higher quality version of CAT5 / CAT5e that supports increased bandwidth of up to 1000 Mbps.
CODEC
A Codec digitizes and compresses a voice signal. The most common are G.711 and G.729.
Contention Ratio
The potential maximum demand related to the actual bandwidth. The higher the contention ratio (e.g.:50:1), the greater the number of users that may be trying to use the actual bandwidth at any one time, and therefore, the lower the effective bandwidth offered. Lower convention ratios are better (e.g.:10:1, 5:1).
Convergence
A technological environment in which any combination of voice, video and data using any combination of fixed and mobile services, may be accessed from any location via any device.
CRM
Customer Relationship Management. Usually regarding computer-based applications for managing client information.
CTI
Computer-Telephony Integration. Allows interactions on a telephone and a computer to be integrated or co-ordinated.
D
DDI
Direct Dialling In. A method of directly dialling the person you require even though they may work in a large organisation served by a switchboard.
DHCP
Dynamic Host Configuration Protocol. A protocol that lets one device on a local network, known as a DHCP server, assign (and re-use) temporary IP addresses to the other network devices, typically computers.
DiffServ
Differentiated Services (i.e.: a mechanism for classifying, managing network traffic and providing QoS; it prioritises IP voice and data traffic to help preserve voice quality, even when network traffic is heavy).
DMZ
(A local area network) De-militarised Zone. A computer or device on an internally protected LAN that is placed outside the firewall but which is still available to the LAN.
DNS
Domain Name Server. Typically the IP address of an ISP’s server; a DNS translates the names of websites into their underlying IP addresses.
DSCP
Differentiated Services (DiffServ) Code Point. The use of a part of an IP header to indicate data traffic importance.
DSL
Digital Subscriber Line. This is is a family of technologies that enables copper telephone lines to carry data-streams at high-speeds. Also known as xDSL, the ‘x’ is simply a placeholder which can be replaced to denote different DSL technologies, such as ADSL.
DSLAM
Digital Subscriber Line Access Multiplexer. Equipment located in a local exchange that aggregates the connections of broadband users into one or more link onto the main internet infrastructure.
E
E1
Echo occurs when some proportion of either user’s call is echoed back.
Echo
A high-bandwidth digital transmission link with a capacity of 2.048 Mbps, used predominantly within ISDN services within Europe. E1 is split into 32 channels each capable of carrying a single voice conversation or data stream.
Ethernet
Ethernet is the most widely-installed local area network (LAN) technology. Most new computers have this capability pre-installed or can be upgraded to take advantage of this connection method. Ethernet is also available on the WAN with leased line technology.
F
Firewall
A security system that prevents computers on a network from communicating directly with computers on another network. Instead, all communication is routed through a proxy server, which determines whether a particular message or file may pass to or from the host.
Follow Me
A call feature that allows calls to find you wherever you are, ringing multiple phones all at once.
FTP
File Transfer Protocol. A standard protocol for sending files between computers via a TCP/IP network / Internet.
FXO
Foreign Exchange Office. A device / card that connects to the PSTN and is the interface offered on a standard telephone. In VoIP, such a device is used to connect an IP PBX system to standard analogue telephone line(s).
FXS
Foreign Exchange Station. A device / card that connects to an ‘end-user’ device such as a fax machine or analogue telephone. In VoIP, such a device is used to connect analogue device(s) such as modems or faxes to IP PBX systems.
G
Group Ringing
A group of extensions is called 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.
GUI
Graphical user interface.
H
Hosting / Hosted
The process of using a ‘virtual’ space in which the user can place their applications and files.
Hunt Group
A group of users allocated to a particular group (e.g.: sales, accounts) to allow for automated distribution (ACD) of incoming calls.
I
IP
Internet Protocol.
IP Telephony
The process of making and receiving voice transmissions over any IP network. IP networks include the Internet, office LANs, and private data networks between corporate offices. Also referred to as VoIP.
ISDN
Integrated Services Digital Network is a type of circuit switched telephone network system designed to allow digital transmission of voice and data over ordinary telephone copper wires, resulting in better quality and higher speeds than available with standard PSTN analogue systems. Typically in the UK, there are two levels of ISDN service: the Basic Rate Interface (BRI) also known as ISDN2 which is intended for the home and small enterprise, and the Primary Rate Interface (PRI) also known as ISDN30, for larger users. ISDN channels can be used flexibly for voice or data and reassigned when necessary to meet special needs (such as videoconferences) and are connected directly to the telephone exchange.
ISDN2
Also known as a BRI, ISDN2 is a 2-channel ISDN Service consisting of 2 x ‘B-channels’ (and 1 x ‘D-channel’) allowing up to 128 Kbps service in total, usually segregated into 2 voice channels.
ISDN30
Also known as PRI. PRI channels are carried on a ‘T-carrier’ (T1) line in the USA, Canada and Japan or on ‘E-carrier’ (E1) line in the UK and other countries. E-carrier ISDN30 is a 30-channel ISDN Service consisting of 30 ‘B-channels’ (and one ‘D-channel’) allowing up to 1.544 Mbps service in total, usually segregated into 30 voice channels. [USA, Canada and Japan ‘T-carrier’ PRI service consists of 23 ‘B-channels’ (and 1 x 64 D-channel) allowing up to 2.048 Mbps service in total, usually segregated into 23 voice channels.]
ISP
Internet Service Provider. A provision for internet connnectivity.
ITSP
Internet Telephony Service Provider (i.e.: a provider of telephony services, such as providing a ‘break out’ conversion of IP calls to normal PSTN calls, via the internet).
J
Jitter
Refers to non-uniform delays that can cause voice data packets to arrive and be processed out of sequence.
K
Kbps
The speed of data transmission measured as the number of thousands of data bits per second.
L
LAN
Local Area Network.
Landline
A landline or main line is a telephone line which travels through a solid medium, either metal wire or optical fibre. This is distinguished from a mobile cellular line, where the medium used is the airwaves.
Latency
This is any delay associated with the time taken for a packet of information (data or voice) to travel from its source to its destination. In digital systems this is the time delay due to analogue to digital conversions, processing, data transmissions and the processing of protocols.
Layer 2
The data link layer of the open systems communication model.
In VoIP terms this is often referred to as providing QoS via VLAN’s whereby a data VLAN is segregated from a voice VLAN, keeping each VLAN’s traffic separated as if they were on a separate physical infrastructure.
Layer 3
The network layer of the open systems communication model.
In VoIP terms this is often referred to as providing QoS via DiffServ whereby ‘marking’ of data takes place using DSCP’s based upon the type of traffic received
Leased Line
A leased line is a symmetric telecommunications line connecting two locations. It is a dedicated non-public line with constant synchronous bandwidth and latency
LES
LAN Extension Services (i.e.: a leased line)
M
MACs
Moves, Adds, Change (and Deletes).
Mbps
The speed of data transmission measured as the number of millions of data bits per second.
Modem
A modem allows your computer to exchange data over the internet. The device converts digital bits into analogue signals (modulates them), so they can be sent over the phone line, cable, satellite link, etc.. When signals come down the line, the device converts them back into digital code (demodulates them) so the computer can use the data.
MOS
Mean opinion score. A measurement of the subjective quality of human speech, represented as a rating index.
MPLS
Multiprotocol Label Switching. MPLS networks simplify and improve IP data exchange and help avoid link failures, congestion, and bottlenecks, minimising latency and packet loss.
N
NAT
Network Address Translation. This is where an internet IP address is translated into a local network address. This is essential if a group of networked computers are sharing the same internet connection and the web content is being distributed to them by a router.
Network
A system that transmits any combination of voice, video and /or data between computers. The network includes the network operating system in the client and server machines, the cables connecting them and all supporting hardware in between such as routers and switches.
NTP
Network Time Protocol. A protocol used to synchronise computer and device clocks over the Internet.
P
Packet
A packet is the fundamental unit of information carriage in all modern computer networks that use packet switching.
Packet Loss
On rare occasions, packet loss will occur in which a portion of the data sent does not arrive at the location intended to receive it. In other words, something goes wrong between the sender and receiver during the call.
Packet Switching
Packet Switching refers to the way that your information will be packaged and then sent over the network. Basically, the pieces are broken up, transmitted separately and put back together on the other end of the transmission.
PBX
A Private Branch eXchange is a telephone exchange that is owned by a private business.
PoE
Power over Ethernet. PoE devices, typically network switches, transmit DC power to the connected devices (e.g.: IP telephone handsets) by carrying power in unused Ethernet network cable wires. PoE enables devices to be installed where there is no AC power outlet and has the advantage that no separate power supply unit or wall power socket is needed. Connected devices that do not make use of PoE may still be connected safely to PoE switches.
POTS
Plain old telephone service. The typical, familiar model of a single phone line and a single phone number.
Presence
Is an indication of the current state of a user, such as ‘Available’, ‘Not Available’, ‘Busy’ or ‘In a Meeting’
PRI
Primary Rate Interface ISDN service. See ISDN30.
PSTN
Public Switched Telephone Network (i.e.: a non-digital standard telephone line).
PWAN
Private Wide Area Network. PWAN’s allow communication between offices / remote workers to be private and secure, in essence emulating the functionality of a LAN but over disparate geographical locations.
Q
QoS
Quality of service. The ability of a network to provide different priority to different applications, users, or data flows and to guarantee a certain level of performance to a data flow. The goal of QoS is to provide guarantees on the ability of a network to deliver predictable results. Elements of network performance within the scope of QoS often include availability (uptime), bandwidth (throughput), latency (delay), and error rate.
R
RAID
Redundant Array of Independent Disks. A category of disk drives whereby two or more drives are used in combination for fault tolerance and performance.
Router
A device that routes data between networks using IP addressing. Typically, a router connects multiple networks together such as a LAN to the Internet.
S
SBC
Session Border Controller. An interface to a network firewall that facilities the secure hand-off of voice packets from one IP network to another. In an enterprise network a SBC controls the communications session as it crosses the border of the LAN. A session in refers to a call, border refers to a point of demarcation between one part of a network and another.
SDSL
Symmetric Digital Subscriber Line. The main difference between ADSL and SDSL is that SDSL has the same upstream data rate as downstream.
Server
A computer that provides services to other computers, or the software that runs on it. Application server is a server dedicated to running certain software applications. A database server provides database services.
SIP
Session Initiation Protocol. The open standard for IP telephone calls.
Softphone
Softphone IP telephony software that lets users send and receive calls from non-dedicated hardware, such as a PC or Pocket PC device. It is typically used with a headset and microphone.
Splitter
A splitter is a special DSL filter that stops your broadband internet signal interfering with your voice signals (for ADSL).
Switch
In networking terms, a switch is a network device that is the central point of connection for computers and other devices in a computer network.
T
T1
A high-bandwidth digital transmission link with a capacity of 1.544 Mbps, used predominantly in North America Canada and Japan. T1 is split into 24 channels each capable of carrying a single voice conversation or data stream.
TAPI
Telephony Application Programming Interface (i.e.: a programming interface that allows Windows client applications to access voice service).
TFTP
Trivial File Transfer Protocol. A version of FTP that does not make of user authentication (passwords).
U
UPS
Uninterruptable Power Supply.
V
VAR
Value Added Reseller. Also called “VAR’s”, or simply “resellers”. Retailers / manufacturers typically add little value to a product, if any at all, and often only channel-sell to VAR’s instead of directly to businesses in order for the VAR to add the required value that they cannot or do not wish to do themselves. The ‘value add’ can come from a wide range of professional services such as consultancy, requirements capture, implementation, customisation, training and support. The VoIP industry is ‘channel based’ and relies heavily on VAR’s.
Voicemail
A voicemail system typically provides a 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.
VLAN
Virtual Local Area Network. A group of computers or devices on a network, regardless of their physical location, which have been configured such that they behave as if they were on a separate – or ‘virtual’ – LAN.
VoIP
Voice over Internet Protocol. The process of making and receiving voice transmissions over any IP network. IP networks include the Internet, office LANs, and private data networks between corporate offices. Also referred to as IP Telephony.
VPN
Virtual Private Network (i.e.: a communications network ‘tunnelled through’ another network, usually dedicated for a specific network use where data is segregated for different user communities over an underlying network with strong security features).
W
WAN
Wide Area Network. A network that spans a large geographic area.
WES
Wholesale Extension Services (i.e.: a leased line). WES provides a high-speed, permanent, point-to-point circuit, offering secure and reliable bandwidth nationally for the transmission of data, voice and video.
WEES
Wholesale End To End Ethernet Service.
X
xDSL
Digital Subscriber Line. This is a family of technologies that enables copper telephone lines to carry data-streams at high-speeds. Also known as xDSL, the ‘x’ is simply a placeholder which can be replaced to denote different DSL technologies, such as ADSL and VDSL.
