Terminology Guide

Automatic Call Distributor: A device or system that distributes incoming calls to a specific group of terminals that agents use. It is often part of a computer telephony integration (CTI) system. The system consists of hardware for the terminals and switches, phonelines, and software for the routing strategy. The routing strategy is a rule-based set of instructions that tells the ACD how calls are handled inside the system.

Asymmetric Digital Subscriber Line: A form of DSL, a data communications technology that enables faster data transmission over copper telephone lines than a conventional voice band modem can provide. It does this by utilizing frequencies that are not used by a voice telephone call.

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 This has largely been replaced by digital transmission.

Automatic Number Identification: Phone number of the calling party. Used for billing and lookup purposes. (keep) ATA Analog Telephony Adapter: A device used to connect one or more standard analog telephones to a digital and/or non-standard telephone system such as a Voice Over IP based network.

Asynchronous Transfer Mode is a means of digital communications that is capable of very high speeds; suitable for transmission of images or voice or video as well as data.

The rate of data flow over a network or the physical capacity between two points Bandwidth .

Refers to bandwidth or a signaling method that handles a wide range of frequencies.

Cable Modem
A form of broadband service that runs over the consumer's cable television network transport line to provide access to the internet.

Phone number of the calling party as presented to the call recipient.

Call Detail Records: A list of data about a telephone call that can be stored and analyzed by the service provider. Data provided includes: time, caller name, number called and, length of call. They form the basic information used by service providers to bill their customers and can also be used to assist in evaluating network performance.

A PBX-like service providing switching from the service provider site instead of at the customer's premise. Unlike PBX, Centrex supports multi-location offices easily. Centrex eliminates the need for separate exchange lines delivered to a site; extensions, called Centrex lines, are delivered directly from the local exchange to the user.

Centrex Data
A service providing relatively low speed data services utilizing circuit-switched telephony network. Although overshadowed by most data networks, Centrex Data offers very flexible and wide-reaching network configurations since connections can be made almost anywhere within the reach of a telephone network.

Name of the calling party as presented to the call recipient.

A program or device capable of decoding and encoding a digital data stream or signals. With VoIP calls, the codec will encode the packets and then decode it at the other end in line that a stream of voice can be heard.

The process of ‘squeezing’ 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. Compression comes in different forms, the higher the compression ratio (i.e. how many times the data is squeezed), the more loss of quality occurs.

Customer Premise Equipment. Any equipment located on the customer's side of a demarcation point (the point that distinguishes where the service provider's equipment ends and where the customer's begins).

The demarcation point is the point at which the telephone company network ends and connects with the wiring at the customer premises.

Dynamic Host Configuration Protocol: A set of rules used by communications devices (computer, routers or network adapters) to allow the device request and obtain an IP address from a server whish has a list of addresses available for assignment.

Direct Inward Dialing (also called DDI in Europe): A feature offered by telephone companies for use with their customers PBX system. The telephone company (telco) assigns a range of numbers all connected to their customer’s PBX. As calls are presented to the PBX, the number dialed by the caller is also given, so the PBX can route calls to the desired person within the organization.

Digital Subscriber Line (DSL) A common form of broadband service that converts a normal phone line into a high speed internet connection.

Digital Transmission
A form of transmission whereby signals are transformed into 1’s and 0’s to be sent over a network. This creates a reduced amount of noise on the line and transmission of the voice is more efficient that in an analog network.

Domain Name System: Internet system used to translate names into IP (Internet Protocol) addresses.

Dual-Tone Multi-Frequency: Telephone signaling also known as “touch tone”.

E911 An enhanced form of the standard number for emergency telephone calls made over the traditional PSTN in North America. E911 automatically provides, to the 911 call center agent, the caller's contact information, including name, address, and telephone number.

Endpoint Any piece of equipment that sits on one end of a communication gateway.

Refers to networking technology, used between computers and other devices on the same Local Area Network (LAN).

Find Me/ Follow Me
Find Me/Follow Me is a feature that routes incoming calls to a user no matter where he or she roams or what type of device is being used (home, business or mobile phone). This “presence” feature, which rings multiple phones simultaneously, is offered by many IP PBXs and some hosted services. The feature is typically activated by pressing a soft key.

Firewall A firewall is a dedicated appliance, or software running on another computer, which inspects network traffic passing through it, and denies or permits passage based on a set of rules..

Frame Relay
A process of transmitting data over a digital network economically and efficiently, in a series of frames.

The Find Me List (FML) is the list you use to set up how inbound callers may reach you. A key component of Digitel Systems’sFind Me/Follow Me feature. It allows you to designate the numbers where you can be reached (in order), when away from your desk. This feature allows you to be available to callers, regardless of your physical location – a must have for road warriors, remote employees and/or anyone who spends time out of the office.

IP Centrex
Centrex – Central Exchange - is a type of switching that works from a central headquarters rather than from the customers’ location.

IP Gateway
Also known as Media Gateway. Translates data from one telecommunication network, in order for it to pass on a different type of network.

IP Phone
A device used to make a Voice Over IP call.

Internet Protocol Private Branch Exchange: A telephone switch (See “PBX”) located on a customer’s premises that utilize VoIP to manage and deliver calls.

IP Soft Phone: Software the enables a computer to function as a VoIP telephone.

Internet Relay Chat: A form of real-time Internet chat or synchronous conferencing. It is mainly designed for group (many-to-many) communication in discussion forums called channels, but also allows one-to-one communication and data transfers via private message.

Internet Service Provider: A company that offers access to the internet through its facilities.

Internet Telephone Service Provider: A company providing connectivity to PSTN for communication with mobile and fixed phones.

Interactive Voice Response: Allows a computer to detect voice and touch tones using a normal phone call. The IVR system can respond with pre-recorded or dynamically generated audio to further direct callers on how to proceed. IVR systems can be used to control almost any function where the interface can be broken down into a series of simple menu choices. Once constructed, IVR systems generally scale well to handle large call volumes.

A sudden and unwanted variation in the characteristics of a signal. This causes a distortion in the sound noticeable by the person being called.

Local Area Network: A series of machines all connected onto the same mini-network covering a small geographic location like a house, office or group of buildings.

LNP (Local Number Portability) – The ability to keep your existing phone number or range of phone numbers. When you purchase VoIP services, make sure your service provider can support LNP, so that you don’t have to change your phone numbers. Providers that support LNP let you keep your existing phone numbers when you move to VoIP.

Multi Location Site: Refers to a customer with multiple locations, such as retail stores, franchises, work-from-anywhere employees, etc.

Mean Opinion Score: The leading subjective measurement of voice quality.

Message Waiting Indicator: The red light for voicemails on your desk phone.

Network Access Device: Describes subscriber equipment required to make a connection to a WAN from a LAN. The NAD normally includes a router, modem and a monitored power supply. Most NAD’s have the ability to report power failures and automatically reconnect themselves back to the network when disconnected. The purpose of a NAD is to reroute calls through a network to provide the best rates for the call destination. Also referred to as dialer or least cost router.

Network Address Translation: Involves re-writing the source and/or destination address of IP packets as they pass through a router or firewall. Most systems using NAT do so in order to enable multiple hosts on a private network to access the Internet using a single public IP address (see gateway).

Packet: A bundle of data, usually in binary form, organized in a specific way for transmission.

Packet Switching: Sending data in packets through a network to a remote location. The data are subdivided into individual packets of data, each with a unique identification and individual destination address. This way each packet can take a different route and may arrive in a different order than it was shipped. The packet ID allows the reassembling of date in the proper sequence.

On-net: In VoIP telephony, refers to calls carried on the customer's network. On-net calls for most telephony plans are free.


Packet Loss
Occurs when one or more packets does not arrive at its final destination. This causes a noticeable gap in the flow of voice – seems like the person talking is missing parts of their speech.

Phone Adapter — An ATA takes the current analog signal your phone provides, converts it into a digital signal and vice versa. An ATA can be used to convert just one phone to a digital phone or to convert an entire house’s phone jacks into a digital phone system.

Phone Jack — A socket connector used to connect telephones in a building to a phone line. A phone jack uses a RJ-11 connection.

Private Branch Exchange: A telephone switch (also known as a PABX, or private automatic branch exchange) located on a customer’s premise that primarily establish voice-grade circuits — over tie lines to a telephone company central office (CO) — between individual users and the public switched telephone network. The PBX also provides switching within the customer premises local area, and usually offers numerous enhanced features, including least-cost routing and call detail recording.

Plain Old Telephone Service: The standard telephone service that most homes use. The POTS network is also called the PSTN.

Public Switched Telephone Network: The traditional network for transporting voice traffic, as opposed to an IP network. Mostly refers to standard analog phone.

Quality of Service. The ability of a network (including applications, hosts, and infrastructure devices) to deliver traffic with minimum delay and maximum availability.

Session Initiation Protocol: An application-layer control (signaling) protocol for creating, modifying, and terminating sessions with one or more participants. These sessions include Internet telephone calls, multimedia distribution and multimedia conferences.

SIP Trunk
SIP trunk is a service offered by an ITSP that permits businesses that have a PBX installed to use VoIP also outside the enterprise network by using the same connection as the Internet connection. There are three components necessary to successfully deploy SIP trunks a PBX with a SIP-enabled trunk side, an enterprise edge device understanding SIP and an ITSP.

Switch — A device owned by your telephone provider connecting two telephone lines together. Often long distance calls are routed through a series of switches until it reaches its end destination. Each time a call is routed through a switch, the owner of the switch charges a rental fee for use on their switch.

Time Division Multiplexing: A type of digital transmission for telephone calls. It is used for most circuit-switch modes of communication with a fixed number of channels and constant bandwidth per channel. (keep)

Toll-free Number

A data circuit running at approximately 1.544 Mbit/s (roughly 60 times more data than a normal residential modem). T2 and T3 circuits carry multiple T1 channels multiplexed, resulting in transmission rates of 6.312 and 44.736 Mbits, respectively.

Designed protocol for VoIP fax. Provides greater resiliency to latency and jitter, more tolerant to packet loss

A Uniform Resource Locator is a type of Uniform Resource Identifier (URI) that specifies where an identified resource is available and the mechanism for retrieving it. In popular language a URL is also referred to as a Web address

Voice Over IP
A network service that supports carrying telephone calls over packetized networks.