ACD (Automatic Call Distributor) - a system that handles incoming call traffic, sending calls to the first available station within predefined groups. If all stations are busy then a recorded message is played and the call is put in queue until a station becomes available.

Analog - a transmission method using continuous electrical signals, varying in amplitude or frequency in response to changes of sound, light, position, etc. impressed on a transducer in the sending unit. The opposite of analog is DIGITAL.

Architecture - the arrangement and design orchestrating the interaction of different elements of a complex communications system. (See also OPEN ARCHITECTURE)

Asynchronous - A transmission method in which information is transferred one discrete character at a time and is delineated by a start and stop indicator at the beginning and end of the character. The opposite of asynchronous is SYNCHRONOUS transmission.

ATM (Asynchronous transfer mode) - Not the money machine! This is an international CCITT standard for high-speed [broadband] packet-switched networks that operates at digital transmission speeds above 1.544 Mbps. This communications protocol specifies how diverse kinds of traffic are transformed into standardized packets which can be managed uniformly within the network.

Attendant - an operator of a PBX console or telephone switchboard.

Bandwidth - The relative range of frequencies that can be passed without distortion by a transmission medium. Greater bandwidths mean a higher information carrying capacity of the transmission circuit. Bandwidth, usually measured in Hertz, is assessed as the number of bits that can be transferred per second.

B channel - Message-bearing 64 Kbps digital channel specified in the ISDN standards. B channels are used for digital transmission of high speed data and video.

Bell Atlantic - One of seven regional bell operation companies (RBOC's) that assumed ownership of the Bell operating companies following AT&T's breakup.

Bell System - Prior to Jan. 1, 1984, an aggregate term for AT&T encompassing 24 Bell operating companies providing local exchange phone service, the AT&T Long Lines Division providing long distance connections, an equipment manufacturing arm known as Western Electric, and a research and development arm known as Bell Laboratories. The Bell System was broken up by the AT&T divestiture.

B-ISDN (Broadband integrated services digital network) - An evolving CCITT international standard for the second generation of integrated services digital networks. Broadband ISDN services will be carried on fiber-optic networks that employ packet switching in a standardized fashion to integrate voice, data, monochrome, and color facsimile images and one-way and two-way monochrome and color video for local and long distance transmission.

Bit - The smallest unit of digital information utilized by electronic or optical information processing, storage, or transmission systems. Bit is short for binary digit. Binary technology is based on the representation of data with 0's and 1's, whose combinations form a protocol medium for all data transmission.

Byte - The smallest unit of information that a computer system can locate within its data storage or memory. A byte consists of eight bits and represents an amount of information roughly equivalent to a single printed or typewritten character.

Call Forwarding - A feature permitting the user to program a phone to ring at an alternate location; call forwarding may be in effect at all times or just when a particular phone is busy or doesn't answer.

Call Hold - A feature allowing the user to put one caller on hold while other calls are made or answered.

Call Park - A feature allowing a call for a busy extension to be put into a hold-like state until someone at that extension or another extension becomes free to answer it. The call is brought out of "park" by dialing a special code.

Call Transfer - A feature allowing a call to be transferred to another phone

Call Waiting - A feature that provides audible or visual indicators to let a single-line-phone user know that she has another call waiting for her.

Caller ID - A telephone company service allowing the subscriber to view the phone number and/or name of the calling party on a display device before answering the phone. Caller ID usually requires some kind of hardware phone interface to provide the displayed information.

Camp-on - In PBX and hybrid environments, a method of putting an incoming or outgoing call intended for a busy extension or line into a hold-like state where it remains until a line becomes available.

Card - A flat piece of rigid material bearing electronic components and the printed circuitry that interconnects them. Cards typically have one point where connections to other cards or components are made.

CCITT (Consultative Committee on International Telegraph and Telephone - the principle international standards-writing body for digital telecom networks (ISDN).

CO (Central Office) - A facility of a telecommunications common carrier where calls are switched. In local area exchanges, central offices switch calls within and between the 10,000-line exchange groups that can be addressed uniquely by the area code and first three digits of a phone number.

Closed System - A computer or communications system whose technical specifications are withheld from distributors, users and other third parties. Closed systems are available only from the manufacturer and its authorized dealers; cloning of closed systems is not tolerated. Buyers of a closed system are limited to the applications programs that the system manufacturer chooses to develop or support. Also known as a proprietary system.

Codec (Coder/Decoder) - a device that transforms analog input into a digitally coded output and transforms digital signals into analog output. They are most commonly found in videoconferencing systems because of videoconferencing's intensive ISDN usage.

Common Carrier - A government-regulated private company offering telecommunications services or communications facilities to the general public.

Conference Call - A telephone call among three or more parties. The sound quality of conference calls is typically degraded by a loss of sound over the telephone lines unless bridged and amplified before re-transmission.

Data Compression - Techniques to reduce the amount of computer memory space or transmission resources required to handle a given quantity of data usually achieved through the application of mathematic algorithms to the data transformation process.

dB - Abbreviation for decibel. The decibel is the standard unit of measure for expressing the amount of signal power gained or lost in the course of a transmission.

D Channel - The signaling and data transmission channel (specified in ISDN standards) used to transmit network control signals for setting up phone calls.

Dedicated Line - A communications circuit or channel provided for the exclusive use of a particular subscriber - also known as a private line.

DID (Direct Inward Dialing) - When a call is received over the DID circuit it is preceded by a packet of information containing the number that was dialed. The on premises phone system decodes this information and routes the call to the extension that has been programmed to coincide with the number dialed. The benefit to the consumer is a pooled access group for incoming calls so that dedicated lines are not required to provide numerous individual telephones with direct access availability.

Digital Switch - Equipment used to set up pathways between users for transmission of digital signals.

DTMF (Dual Tone Multi Frequency Signaling) - Most commonly associated with AT&T's Touch-Tone trade name.

Duplex - Simultaneous transmission in both directions, sometimes referred to as full duplex to differentiate it from half duplex, which is alternating transmission in each direction. Transmission in only one direction is called simplex transmission.

800 Service - A telecommunications service for businesses that allows calls to be made to a specific location at no charge to the calling party. Use of the "800" service access code denotes that calls are to be billed to the receiving party.

Encoder/Decoder - A device used to transform signals from an originating terminal into groups of digital pulses representing letters, numerals, or specific symbols, and transform incoming digital pulses into the form required by the receiving terminal.

Ethernet - A popular local area data communications network, originally developed by Xerox Corp., which accepts transmissions from computers and terminals.

Facilities - Transmission lines, switches and other physical components used to provide telephone service.

Fax - A method of transmitting graphics or text documents over a telecommunications facility. The image is scanned at the transmitter and reconstructed at the receiver to be duplicated on paper.

Fiber Optics - Technology based on thin filaments of glass or other transparent materials used as the medium for transmitting coded light pulses that represent data, image and sound. Fiber optic technology offers extremely high transmission speeds.

Full Duplex - A communications system or channel capable of simultaneous transmission in two directions. See Duplex.

Gateway - A network element interconnecting two otherwise incompatible networks, network nodes, subnetworks or devices.

Half Duplex - A communications channel allowing alternating transmission in two directions, but not in both directions simultaneously.

Hybrid - A combination of two or more technologies or a multiline business telephone system combining the manual line selection of a key system and the automatic line selection of a PBX system.

Interconnect - A company or vendor selling customer premises equipment, generally PBXs and other types of office telephone systems. An interconnect company is typically an independent distributor of products from more than one manufacturer.

ISDN (Integrated Services Digital Network) - Switched network providing end - to -end digital connectivity for simultaneous transmission of voice and/or data over multiple multiplexed communications channels and employing transmission and out-of-band signaling protocols that conform to internationally defined standards.

IVR (Interactive Voice Response) - A generic term for transaction systems allowing phone callers to use an ordinary tone-dialing telephone to interact with a computer through speech or dialed instructions. Each response by the caller triggers another recorded message until the transaction is completed.

Key Telephone System - A multiline telephone system offering a limited range of features; key systems are popular among smaller businesses as their main telephone system. They are also found in large businesses as a form of extension to their big primary phone system. Key systems are characterized by manual selection of outgoing lines, their small size, and relatively low price.

LAN (Local Area Network) - A transmission network encompassing a limited area, such as a single building or several buildings in close proximity; widely used to link personal computers so that they can share information and peripheral devices.

LED (Light-Emitting Diode) - A semiconductor light source that emits light in the optical frequency band or the infrared frequency band.

Local Loop - The communications channel, usually a physical line, between the subscriber's location and his local central office. Also known as the subscriber loop.

Loop Start - A method of demanding dial tone from the central office by completing an electrical pathway between the outbound and return conductors of a telephone line. Loop start is employed by single-line telephone instruments, for example.

Measured Service - Term generally associated with providing local telephone service on a usage-sensitive basis with calls priced on the basis of two or more of the following usage elements: distance, duration, frequency, and time of day. It is the opposite of flat rate pricing.

Message Rate - A form of usage-sensitive pricing for local telephone service where usage charges are figured by counting the calls and multiplying the number of calls made by the established per-call charge. An alternative to flat-rate and measured pricing.

Modem (Modulator-Demodulator ) - An electronic device that allows computers to communicate over standard telephone lines. It transforms digital signal into analog signal and transmits to another modem which then reconstructs the digital signal from the analog signal.

Multiplexed Channel - A communications channel capable of serving several devices, or users, at once

Multiplexing - An electronic or optical process that combines a large number of lower-speed transmission lines into one high-speed line by splitting the total available bandwidth of the high-speed line into narrower bands (frequency division), or by allotting a common channel to several different transmitting devices, one at a time in sequence (time division). Multiplexing devices are widely employed in networks to improve efficiency by concentrating traffic.

Mux - An abbreviated form of the word multiplexer.

Network - Any system designed to provide one or more access paths for communications between users at different geographic locations that may include designs for voice, data, facsimile images and/or video images.

Network Architecture - A set of design principles defining the protocol, functions and logical components of a network and how they should perform.

Network Interface - The physical point in a telephone subscriber's home or place of business where the telephone devices and/or inside wiring of the subscriber are connected to the transmission lines of the local telephone service provider.

OEM (Original Equipment Manufacturer) - The manufacturer of equipment that is resold by another vendor who usually substitute their name for that of the manufacturer on the product.

Off-Hook - A telephone set in use - the handset is removed from its cradle, thus sending an electrical signal to the central office that a circuit needs to be opened.

Off-Line - The condition where a terminal or device capable of active connection with the facilities of a computer or communications network is in the disconnected or idle state.

1A2 - Widely-used type of electromechanical key system that were introduced by the Bell System in 1938 and reached their technological peak in the mid-1960's.

On-Hook - The normal state of the phone in which the handset rests in the cradle and the circuit to the central office conducts no electrical signal.

On-Line - The condition where a terminal or device capable of active connection with the facilities of a communications network or computer is in the active or connected state; a unit functioning under the continual control of a computer.

Open Standard - A computer or communications standard whose technical specifications are readily available to equipment manufacturers and other parties that want to incorporate the standard into their products or systems.

Open System - A computer or communications system whose technical specifications are readily available to distributors, users and other third parties that want to add value to the system by developing their own customized versions for use or resale. Open systems are widely cloned.

Operating System - A special program in the communications CPU or computer that controls the integration of operating devices and enables the running of specific applications software - which is software developed to perform specific jobs.

Packet - a group of binary digits switched as a whole - for instance, a file transfer over a packet switched network would require many steps. These steps are: 1) the data file would be broken down into smaller "packets" of information 2) each packet of information is assigned a code that enables it to be sent to the correct location and, once at that location, for the network to reassemble the packets of information into their original form.

Packet Switched Network - A digital data transmission network that uses packet switching technology.

Packet Switching - a digital data transmission method that divides messages and files into standard-size pieces - called packets - that are switched across networks individually and then reassembled at their destination.

Paging - A service designed to deliver numeric or alphanumeric messaging to a person whose location is uncertain - paging services make use of radio communications.

PBX (Private Branch Exchange) - A device, installed on the customer's premises, that enables switching of multiple incoming and outgoing lines between multiple internal phones. In addition, the typical PBX provides for the selection of outside lines per user defined criteria.

Port - An interface location on a computer or communications system that provides a point of access for peripheral equipment, such as printers, voice mail, C.O. Lines, etc.

POTS Lines (Plain Old Telephone Service Lines) - Basic telephone lines whose primary purpose is the transmission of human speech.

Private Line - A telephone line that is linked directly to a user and is used exclusively by that user.

Private Network - A network that is designed for use exclusively by a person or organization and usually does not have points of access from users external to the company.

Programming Language - A group of symbols that represent to the computer a set of statements or directions giving the computer or communications system detailed instructions about what operations it is to perform.

Proprietary System - See closed system.

Protocol - A format or set of rules and conventions that control the format and relative timing of message transmission between two points on a computer network.

Public Switched Network - A switching system that provides switching and transmission facilities to many customers.

Queue - A "holding room" for data or voice communications that are waiting to be processed by either the system or human intervention.

RBOC (Regional Bell Operating Corporation) - One of seven regional companies created by the AT&T divestiture to take over ownership and operation of the Bell companies within their region.

Real Time - A transmission or data processing operational mode in which the data is entered in an interactive (two-way communicating) session; an application where response to input is fast enough to affect later data input.

Redundancy - Having back-up systems available to provide continuous service in the case of a failure in the main system

Remote Access - Sending and receiving data to and from a computer through communications links such as phone lines.

Remote Call Forwarding - Similar to call forwarding. Calls from a local telephone number can be forwarded to long distance number (in another city for example) without the caller be charged for long distance fees.

Serial Transmission - Sending pulses (information) one right after another. The opposite would be a parallel transmission.

SMDR (Station Message Detail Reporting) - Information recorded by a computer attached to the phone system, providing cost accounting information such as the number of calls, both local and long distance, made from an extension during a certain time period.

Speed Dial - A feature on PBX phones allowing users to dial programmed numbers by simply pressing one button (or entering a two or three digit code).

Station - Simply another word for telephone. For example, the telephone station may be one of many extensions on a PBX system.

Station Hunting - A feature allowing an incoming call to a busy phone to be routed to the next idle phone in a pre-determined group of phones.

Switched Line - A circuit which is routed through a circuit switched network.

Switching - Connecting the caller to the called party.

Synchronous Transmission - Transmissions of data at a fixed rate, eliminating the need for start and stop bits, because the receiver and transmitter work at the same rate.

TCP/IP (Transmission Control Protocol/Internet Program) - Protocols linking dissimilar computers across networks. TCP/IP was developed by the Department of Defense

TDMA (Time Division Multiple Access) - Multiple conversations are separated by dividing bandwidths into finite frequencies., where each call is assigned a transmission timeslot.

Telecommunications - Process of converting sounds and data into electrical impulses that can be transmitted (See Telephony).

Telecommuting - Using a communications link to perform work, rather than actually commuting to an office to do work.

Teleconference - A conference which links people by audio and/or video through telecommunications.

Telemarketing -Using the telephone as a primary means of initiating and making sales of products or services.

Telephony - The process of converting sounds into electrical impulses for transmission over a connecting medium such as wires, fiber optics or microwave.

Terminal - The point of connection between a telephone line and an operative device. Also, sometimes terminal refers to the operative device, such as a computer terminal.

Tie Line - A telephone line which is dedicated to connecting two points and which requires a minimum human intervention to achieve communication.

Token Ring -A method of controlling which of several work stations in a Local Area Network is transmitting at a particular time.

Toll Restriction - A method of controlling which employees, if any, have access to telephone lines for which a toll may be charged to the employer.

T-1 - A digital transmission link capable of handling 1.544 Mega bits per second.

Trunk - The line of communication between switching systems.

T-3 - 28 T-1 lines (See T-1).

Turnkey - A ready-to-go telephone system installed by the vendor, including both hardware and software.

Twin-Axial Cable - Two commonly insulated conductors, covered by a metallic shield and enclosed in a cable sheath.

Twisted Pair - Two copper wires twisted around each other. The twists vary in length and reduce induction.

Videoconferencing - Video teleconferencing (See teleconferencing).

Voice Digitization - Coverting analog signals (voice) into binary bits for storage and transmission.

Voice Response - A computer allowing users interaction via touchtone telephone. Users navaigate the system with the help of digitally read menus.

WAN (Wide Area Network) - A network that extends LANs to other LANs, typically over a wide geographical area using communications lines provided by a common-carrier.

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