Telecommunications Dictionary & Terms

This is a list of telecommunications definitions for words such as CDMA, cellular, EDI, fiber optic, gsm, TDMA, packet switching, PCS - and many more telecommunication acronyms or phrases. See also our Telecommunications Glossary and our Technical Archive Index, and do e-mail us with any suggestions for additions to this dictionary.

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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.

Acoustic Coupler

This is a special cradle in which you place the handset of a phone. This is connected to a modem, and the modem accesses the phone line through this coupler. Modern modems connect directly to the phone line.

AMPS

(Advanced Mobile Phone Service) The analog cellular mobile phone system in North and South America and more than 35 other countries. It uses the FDMA transmission technology. AMPS is the cellular equivalent of POTS.

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. Analogue data often comes from measurements, like a sine wave. The opposite of analog is DIGITAL.

ANSI

ANSI graphics is a set of cursor control codes which originated on the VT100 smart terminal. Many BBS's use these codes to help improve the sending of characters to communications programs. It uses the escape character, followed by other characters, which allows movement of the cursor on the screen, a change of color, and more.

Archie

A program and database which locates files on the Internet.

Architecture

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

ARPANET

From ARPA (Advanced Research Projects Agency) and network. An early experimental network.

ASCII

American Standard Code of Information Interchange. It uses 7 bits to represent all uppercase and lowercase characters, as well as numbers, punctuation marks, and other characters. ASCII often uses 8 bits in the form of bytes and ignores the first bit.

ASCII transfer

When a text file is sent directly as it is, without any special codes.

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. This way, if there is line noise, the modem can find out right away where the next byte should start. The opposite of asynchronous is SYNCHRONOUS transmission.

AT command

Any instructions sent to a modem that begin with "AT".

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.

Auto Reliable

The ability of a modem to be able to communicate both with modems that do have error-control and/or data compression, and those that do not.

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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.

The difference between the upper and lower limits of a band. A range of radio, audio, or other frequencies. Since it is so limited, a modem must carefully change data into sounds that "fit" within this range. Similar to frequency spectrum. Bandwidth of a voice channel is 3000Hz-300Hz which equals 2700Hz. Telephone lines have a bandwidth from 300 hertz to 3400 hertz.

BASIC

Beginners All-purpose Symbolic Instruction Code. It is a programming language. It is called symbolic because it allows programmers to use symbols to represent numbers and information. In algebra, these symbols are called variables.

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.

Balun

Balanced/unbalanced. A device which connects a balanced (two-wire) line, such as a phone line, to an unbalanced (coaxial) line, like cable. The two-wire line is called balanced because the currents in each wire are equal and in opposite directions.

Baud

A term referring to the speed at which modems communicate. Technically, it is the number of changes in an electronic signal per second. Since the number of changes used to be the same as the number of bits sent or received per second, bps and baud are often used interchangeably. However, there is a difference, which is very often confused. For example, many 1200bps modems were advertised as 1200 baud, even though they operate at 600 baud. They send out 2 bits 600 times a second, which means that it is 600 baud. However, since it is so often misunderstood, you can assume that when you see "baud" it means bits per second, unless it is stated otherwise. The term comes from the scientist J. M. E. Baudot.

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.

BFT

Binary File Transfer

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. See also 8-N-1 in # section.

BPS

Bits Per Second. The transmission speed of most modems is measured in baud or bps. Bps is literally the number of bits sent by the modem every second.

Block size

When used with either error control or data compression protocols, refers to the number of characters to be sent at one time. If error control is used, the codes are sent immediately following this block. Typical block sizes are 64, 128, 192, or 256 characters. Small block sizes are better when the line quality is bad (such as for long distance calls), while large block sizes are better during good connections (such as for local calls).

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.

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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.

Card Services

DOS and Windows 3.1x users must have Card Services enabled to use their computer's PCMCIA slot(s). They will automatically allocate a Communications Port (COM 1 to 5) when the Option modem is plugged in. The Option modem can then be accessed by communications programs via the Windows 95-assigned COM port. Windows 95 users DO NOT need to install Card Service as it is built into Windows 95. Notebook users using DOS/Windows 3.1 usually have the Card Services software bundled with their purchase. Option modems come packaged with a PC Card Installation disk that has an install program for these Card Services.

CCITT (Consultative Committee on International Telegraph and Telephone

The principle international standards-writing body for digital telecom networks (ISDN).

Carrier Detect

The information as to whether or not the modem senses a carrier, like a fixed-line dialling tone or a data/fax services enabled on a GSM subscription.

CIS

Card Information Services. A PCMCIA setup protocol.

CDMA

Short for Code-Division Multiple Access, a digital cellular technology that uses spread-spectrum techniques. Unlike competing systems, such as GSM, that use time-division multiplexing (TDM), CDMA does not assign a specific frequency to each user. Instead, every channel uses the full available spectrum. Individual conversations are encoded with a pseudo-random digital sequence. CDMA was developed by Qualcomm, Inc.

CDPD

Short for Cellular Digital Packet Data, a data transmission technology developed for use on cellular phone frequencies. CDPD uses unused cellular channels (in the 800- to 900-MHz range) to transmit data in packets. This technology offers data transfer rates of up to 19.2 Kbps, quicker call set up, and better error correction than using modems on an analog cellular channel.

CDPR

Cellular Digital Packet Radio.

Cell

In communications and networking, a fixed-size packet of data.

In cellular telephone systems, a geographic area.

Cellular

Refers to communications systems, especially the Advance Mobile Phone Service (AMPS), that divide a geographic region into sections, called cells. The purpose of this division is to make the most use out of a limited number of transmission frequencies.

Each connection, or conversation, requires its own dedicated frequency, and the total number of available frequencies is about 1,000. To support more than 1,000 simultaneous conversations, cellular systems allocate a set number of frequencies for each cell. Two cells can use the same frequency for different conversations so long as the cells are not adjacent to each other.

For digital communications, several competing cellular systems exist, including GSM and CDMA.

Checksum

A number that represents a larger group of numbers in order to check for errors in data transmission. It is commonly used when downloading a program, as well as in error control protocols. The checksum is the result of a mathematical equation, such as adding all the numbers in a block together (although it is usually more complex than that).

Chip Set

A group of important IC chips on a modem (or other computer peripheral) that are all made by the same manufacturer. While there are many companies that make modems, there are only a few that make the chips for them. Because the chip manufacturer is making the chips for many companies, they produce more chips, and the price of the chips is lower than if each company produced their own. This decreases the price of the modems on the market.

CLIP

Caller Line ID Presentation. A code that is sent over the phone lines in some areas when a person makes a phone call. This code includes the phone number of the person making the call. Some modems are able to understand this signal, and let you know who is calling you before you answer the phone.

CMOS

Complementary Metal Oxide Semiconductor. A chip which uses small amounts of electricity. It is used typically on battery-powered computers and to save configuration information on other computers when they are turned off.

CLIR

Caller Line ID Restriction. The ability to block someone who you're calling from seeing your number.

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.

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.

Communciations Program

A program that controls a modem, and has features that allow the user to do such things as upload, download, etc. It is similar to a terminal program but more sophisticated. An example is Trumpet WinSock for connecting to the Internet, and Windows HyperTerminal.

Compress

To make data take up less space. Archiving programs do this, which means that files will take less time to transfer with modems. Many modems now have the ability to automatically compress the information they send and receive.

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.

CTS

Clear To Send. This is when the modem lets the other computer know that it can send information to the other computer.

CTS/RTS

The method of flow control that uses the CTS and RTS signals. It is built into the hardware, not software.

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DAA

Data Access Arrangement. A device used to connect modems to the switched telephone network.

D-AMPS

(Digital-Advanced Mobile Phone Service) The digital equivalent of the analog cellular phone service. Using the TDMA digital technology, analog cellphone systems can be upgraded to D-AMPS.

DCE

Data Circuit Terminating Equipment. Sets up and maintains a data connection link over a communications medium. For example, a modem.

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.

Data Transmission rate

The speed at which data travels. For example, data may be sent at 115,200bps. Same as transmission rate, transmission speed, data rate.

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

A system using discrete numbers to represent data. In computer systems, these are the numbers 0 and 1 (for binary).

Digital Switch

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

DSR

Data Set Ready. This indicates that the modem is on, and ready to accept input from the computer (either commands or data to be sent over the phone line).

DTMF (Dual Tone Multi Frequency Signaling)

Most commonly associated with AT&T's Touch-Tone trade name.

DTR

Data Terminal Ready. The DTR signal is sent from the computer to the modem, to let the modem know that the computer is ready to communicate.

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.

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EDI

Short for Electronic Data Interchange, the transfer of data between different companies using networks, such as the Internet. As more and more companies get connected to the Internet, EDI is becoming increasingly important as an easy mechanism for companies to buy, sell, and trade information. ANSI has approved a set of EDI standards known as the X12 standards

EEPROM

Electrically Erasable Programmable Read-Only Memory.

EFF

Electronic Frontier Foundation. An organization promoting civil rights in cyberspace. It is leading the fight against the US government's Clipper Chip.

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.

Error Correction

Error Correction. The ability of a modem to notice errors in transmission, and to resend incorrect data.

ETSI

European Telecommunications Standards Institute.

ECFP

European Conference on Computers, Freedom, and Privacy.

ESPRIT

European Strategic Program for Research in Information Technologies.

Ethernet

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

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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 optic

A technology that uses glass (or plastic) threads (fibers) to transmit data. A fiber optic cable consists of a bundle of glass threads, each of which is capable of transmitting messages modulated onto light waves. Fiber optics has several advantages over traditional metal communications lines:
Fiber optic cables have a much greater bandwidth than metal cables. This means that they can carry more data. Fiber optic cables are less susceptible than metal cables to interference. Fiber optic cables are much thinner and lighter than metal wires. Data can be transmitted digitally (the natural form for computer data) rather than analogically.

The main disadvantage of fiber optics is that the cables are expensive to install. In addition, they are more fragile than wire and are difficult to split. Fiber optics. Fiber optics: is a particularly popular technology for local-area networks. In addition, telephone companies are steadily replacing traditional telephone lines with fiber optic cables. In the future, almost all communications will employ

Firewall

Computer security that attempts to keep crackers out.

Flow control

A method of controlling when information is sent. One method is Xon/Xoff, where a BBS will send information until your computer sends an Xoff (CTRL-S). It will resume sending information when you send an Xon.

Full Duplex

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

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Gateway

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

GMSK

The method of modulation used by GSM is Gaussian Minimum Shift Keying (GMSK), with a BT value of 0.3 at a gross data rate of 270 kb/s.

Group III Fax

The standard controlling fax communication.

GPRS

General Packet Radio Service is a standard for wireless communications which runs at speeds up to 150 kilobits per second, compared with current GSM (Global System for Mobile Communications) systems' 9.6 kilobits.

GPRS, which supports a wide range of bandwidths, is an efficient use of limited bandwidth and is particularly suited for sending and receiving small bursts of data, such as e-mail and Web browsing, as well as large volumes of data.

GSM

Short for Global System for Mobile Communications, one of the leading digital cellular systems. GSM uses narrowband TDMA, which allows eight simultaneous calls on the same radio frequency.

GSM was first introduced in 1991. As of the end of 1997, GSM service was available in more than 100 countries and has become the de facto standard in Europe and Asia.

GSM South Africa was one of the first to implement Phase 2 of GSM.

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Half Duplex

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

Handover

What occurs when a cell phone used in a car moves out of the range of one cell and needs to connect to the next available cell. The preceding cell then hands over the connection to the stronger cell.

Hayes AT Command set

This is the set of commands used to operate Hayes modems and Hayes compatible modems. Almost all of the commands start with AT.

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.

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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.

IMT 2000

An effort similar to UMTS is underway in ITU under the name of FPLMTS (Future Public Land Mobile Telecommunication System) lately remamed to the more catchy IMT-2000 (International Mobile Telecommunication 2000). It is expected that UMTS and IMT-2000 will be compatible so as to provide global roaming but it is too early yet to say whether this goal will eventually be achieved.

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.

ISO

The International Standards Organisation, the body responsible for setting world technical standards. It is based in Geneva, Switzerland.

ITU

International Telecommunications Union, based in Geneva, Switzerland.

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.

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Jack

A socket, hole or opening mounted on a wall, switchboard or panel, into which a plug connector can be inserted to complete a connection.

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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.

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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.

Lotus

Famous for the Lotus 1-2-3 spreadsheet of the 1980's, and more recently for it's Notes Groupware system. Bought by IBM in 1995.

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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.

Microsoft

The world's largest developer and publisher of software based in Redmond, Seattle, USA. Headed by William (Bill) Gates, the richest (non-royal) person on this planet.

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.

Mosaic

A GUI (Graphical User Interface) for accessing the hypertext WWW (World Wide Web) on the Internet.

MNP

Microcom Networking Protocol. Error control and data compression techniques, created by Microcom, that many newer modems use. They are built into the modem, unlike software error correction in file transfer protocols. There are different MNP levels. Levels 1-4 are error control protocols, and level 5 is a data compression protocol that can compress data to about 50% of its original size. A modem with MNP-5 also has MNP-4. MNP 1-4 is also included in the ITU V.42 error correction system.

MoU

Memorandum of Understanding, the GSM body that overseas GSM standards and implementation around the world. It comprises operators and some manufacturers.

Modem

A MOdulator DEModulator computer peripheral which allows a computer to communicate over telephone lines. This is the heart of computer telecommunications. The main factor that differentiates modems is their speed, measured in bps. Analogue modems talk to one another by converting digital info from the computer into tones called PSK’s. An ordinary analogue modem cannot be physically connected to a GSM phone because networks will not carry PSK tones.

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.

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N-AMPS

(Narrow-bandwidth AMPS) A version of the analog cellular mobile phone system that uses a narrower bandwidth.

NCAIR

National Center for Automated Information Research.

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.

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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.

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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

Refers to protocols in which messages are divided into packets before they are sent. Each packet is then transmitted individually and can even follow different routes to its destination. Once all the packets forming a message arrive at the destination, they are recompiled into the original message.

Most modern Wide Area Network (WAN) protocols, including TCP/IP, X.25, and Frame Relay, are based on packet-switching technologies. In contrast, normal telephone service is based on a circuit-switching technology, in which a dedicated line is allocated for transmission between two parties. Circuit-switching is ideal when data must be transmitted quickly and must arrive in the same order in which it's sent. This is the case with most real-time data, such as live audio and video. Packet switching is more efficient and robust for data that can withstand some delays in transmission, such as e-mail messages and Web pages.

Paging

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

Parity Bit

Most modems have the capability to send an extra bit for every byte sent, which is used to help sense errors. This is called the parity bit. It can be set to no parity, mark parity, space parity, odd parity or even parity. Most BBS's do not use a parity bit.

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.

PBX (2)

Short for private branch exchange, a private telephone network used within an enterprise. Users of the PBX share a certain number of outside lines for making telephone calls external to the PBX.

Most medium-sized and larger companies use a PBX because it's much less expensive than connecting an external telephone line to every telephone in the organization. In addition, it's easier to call someone within a PBX because the number you need to dial is typically just 3 or 4 digits.

A new variation on the PBX theme is the centrex, which is a PBX with all switching occurring at a local telephone office instead of at the company's premises.

PC Cards

Previously known as PCMCIA cards, these are credit card devices used in notebooks and desktop readers for inter alia, data/fax, storage, GPS puposes.

PCS

Short for Personal Communications Service, the U.S. Federal Communications Commission (FCC) term used to describe a set of digital cellular technologies being deployed in the U.S. PCS includes CDMA (also called IS-95), GSM, and North American TDMA (also called IS-136). Two of the most important distinguishing features of PCS systems are:

1. They are completely digital
2. They operate at the 1900 MHz frequency range

PKZIP

The program which will create an archive with the extension "ZIP". It is one of the most popular archive programs.

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.

PSTN

Public Switched Telephone Network. This is the regular phone lines that just about everybody uses.

Public Switched Network

A switching system that provides switching and transmission facilities to many customers.

Pulse Dialing

A method that some phones use to dial numbers. It involves a series of "clicks." Most modems support this type of dialing, which is the only type available in some remote areas. The other method of dialing is tone dialing.

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Queue

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

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RACE

Research and Development in Advanced Communication in Europe.

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.

Reset

A modem can be reset. This will change any options (such as parity and speed) to the values that they have when the modem is first used. This can be useful if you change some values for the modem and aren't sure what they do, and then you find that the modem won't work. Resetting the modem will fix everything for you.

RLP - Radio Link Protocol

Non-transparent data uses a special ensure robust GSM-specific error correction technique called RLP for transmission. Both MTN and Vodacom GSM networks support both techniques.

RPE-LPE

Regular Pulse Excitation - Long Term Prediction, the speech coding used by GSM.

RTS

Request To Send. This is when the computer tells the modem that it wants to send information to the other computer. It is only used in half duplex mode.

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Serial Transmission

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

SIM

Subscriber Identity Module. This is a Smart Card installed in every GSM handset. Within the GSM application the three primary roles of the SIM are access control to the network (authentication & ciphering), service personalisation (SMS, advice of charge, etc.), network branding and advertising (graphics printed on SIM card). The new generation of Phase 2+ SIMs will enable services such as virtual cash, mobile banking, ticket reservations etc.

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.

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T-1

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

T-3

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

TCP/IP (Transmission Control Protocol/Internet Program)

Protocols linking dissimilar computers across networks. TCP/IP was developed by the Department of Defense

TDM

Short for Time Division Multiplexing, a type of multiplexing that combines data streams by assigning each stream a different time slot in a set. TDM repeatedly transmits a fixed sequence of time slots over a single transmission channel. Within T-Carrier systems, such as T-1 and T-3, TDM combines Pulse Code Modulated (PCM) streams created for each conversation or data stream.

TDMA

Sort for Time Division Multiple Access, a technology for delivering digital wireless service using time-division multiplexing (TDM). TDMA works by dividing a radio frequency into time slots and then allocating slots to multiple calls. In this way, a single frequency can support multiple, simultaneous data channels. TDMA is used by the GSM digital cellular system.

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.

Telkom (South Africa)

Telkom is the parastatal fixed-line network operator in South Africa. Option modems are approved for use on the telkom network and 25 other networks around the world.

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.

Tone Dialing

This is a method that a phone or modem can use to dial a phone number. It uses one audible tone per digit to be dialed.

Transmit Level

The "loudness" level of the sound leaving a modem to go over the phone lines. It is measured indBm's. It should be different at different frequencies, since certain frequencies have more loss over the phone line than others.

Trunk

The line of communication between switching systems.

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.

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UART

Universal Asynchronous Receiver/Transmitter. This is a device in a computer or modem that will change serial data (the way data comes in over the phone line) to parallel, and vice versa. (See more details below in # section)

UMTS

Universal Mobile Telecommunication System - UMTS is a third generation mobile communication system currently being developed in Europe. UMTS related activities are lead by research conducted within the RACE II program and standardisation activities within the Europian Telecommunication Standards Institute (ETSI).

Some requirements
1. To support existing mobile services and fixed telecommunications services up to 2Mbit/s.
2. To support unique mobile services such as navigation, vehicle location, and road traffic information services, which will become increasingly important in a pan-European market.
3. To allow the UMTS terminal to be used anywhere, in the home, the office, and in the public environment, both in rural areas and city centres.
4. To offer a range of mobile terminals from a low cost pocket telephone (to be used by almost anyone anywhere) to sophisticated terminals to provide advanced video and data services.

Click here to read more

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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.

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W3

World Wide Web.

WWW

World Wide Web. A hypertext system set up on the Internet.

Waffle

A DOS program to perform UUCICO.

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.

WAP

The Wireless Application Protocol is a secure specification that allows users to access information instantly via handheld wireless devices such as mobile phones, pagers, two-way radios, smartphones and communicators.

WAP supports most wireless networks. These include CDPD, CDMA, GSM, PDC, PHS, TDMA, FLEX, ReFLEX, iDEN, TETRA, DECT, DataTAC, and Mobitex.

WAP is supported by all operating systems. Ones specifically engineered for handheld devices include PalmOS, EPOC, Windows CE, FLEXOS, OS/9, and JavaOS.

WAPs that use displays and access the Internet run what are called microbrowsers--browsers with small file sizes that can accommodate the low memory constraints of handheld devices and the the low-bandwidth constraints of a wireless-handheld network.

Although WAP supports HTML and XML, the WML language (an XML application) is specifically devised for small screens and one-hand navigation without a keyboard. WML is scalable from two-line text displays up through graphic screens found on items such as smart phones and communicators. WAP also supports WMLScript. It is similar to JavaScript, but makes minimal demands on memory and CPU power because it does not contain many of the unnecessary functions found in other scripting languages. Because WAP is fairly new, it is not a formal standard yet. It is still an initiative that was started by Unwired Planet, Motorola, Nokia, and Ericsson.

Winsock

A Windows subroutine library that provides access to the Internet TCP/IP.

WINSOCK.DLL

The actual file containing Winsock.

WOSA

(Windows Open Service Architecture) A framework of open-ended interfaces allowing Microsoft Windows and applications running under it to integrate with enterprise computing environments. It includes APIs for messaging (MAPI), standard access to databases (ODBC) and extensions to financial services.

Workflow automation The flow of documents around an organization in a prescribed order (workflow) can be automated, delivering an hierarchical and controlled form of workgroup computing. Workgroup computing - Method of organizing a business around productive teams using computer support to enable cooperative working and to eliminate time/space restrictions. An extension of conventional LAN working.

Workstation Term used freely to mean a PC, node, terminal or high-end desktop processor (for CAD/CAM and similar intensive applications) - in short, a device that has data input and output and operated by a user.

Wrap Redundancy measure in IBM token ring LANs. Trunk cabling used in token ring TCUs contains two data paths: a main and back-up (normally unused). If the trunk cable is faulty, the physical disconnection of the connector at a TCU causes the signal from the main path to wrap onto the back-up and maintain the loop.

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Xmodem

A file transfer protocol developed by Ward Christensen around 1977. It is fairly slow by today's standards, but was the first widespread file transfer protocol. It uses blocks of 128 bytes, and after each block is sent, it sends a 1 byte checksum to check for errors. If an error is encountered, the block will be re-sent. Almost every communications program offers this protocol.

Xmodem/CRC

The same as Xmodem, but it has a 16-bit CRC instead of the checksum, which makes it more reliable (it catches more errors).

Xoff

The CTRL-S character. This is often used to pause information that is being sent. The information will be continued when an CTRL-Q is received.

Xon

The CTRL-Q character. This will sometimes continue paused information.

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y-mount

A variation of the basic altitude over azimuth antenna mount, with the primary axis parallel to the Earth's surface for improved zenith tracking, such as might be used in telescope mounts and satellite. See also y-mount.

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ZIP

The file extension which refers to archives that were created by the program PKZIP. You need the program PKUNZIP to get the files out of the archive.

Zmodem

A file transfer protocol which is known for its speed, as well as the ability to transfer information about the files which it sends. It has crash recovery and auto-download features, and can use a 32 bit CRC, which makes it almost error-free.

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8-N-1

The most common modem format. "8N1" describes the way that your computer and the remote are connected. The first digit is normally 7 or 8, the number of data bits. The second character is a letter describing the parity (N for None, M for Mark, S for Space, O for Odd, and E for Even). The last number is the number of stop bits. Data is sent as follows: Start bit (0) 7 or 8 bits of data (parity bit, if used) stop bit (1) (gap bits, if used)

10BASE-T

An ethernet connection that uses UTP (unshielded twisted-pair) wiring.

16550 UART

This is the UART used with most newer computers and high speed modems. There are several variations, but they all include one main feature: they include buffering, so that if data comes in or is sent faster than the computer/modem can accept it, the UART will hold the data (up to 16 bytes) until the computer/modem is ready for it. (See UART).

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