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.
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.
Stands for Asynchronous Digital Subscriber Line and turns your existing telephone line into a digital connection.
(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.
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 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.
A program and database which locates files on the Internet.
The arrangement and design orchestrating the interaction of different elements of a complex communications system.
From ARPA (Advanced Research Projects Agency) and network. An early experimental network.
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.
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.
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.
An operator of a PBX console or telephone switchboard.
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.
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.
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.
Message-bearing 64 Kbps digital channel specified in the ISDN standards. B channels are used for digital transmission of high speed data and video.
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.
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.
One of seven regional bell operation companies (RBOC's) that assumed ownership of the Bell operating companies following AT&T's breakup.
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.
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
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.
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.
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).
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.
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.
A feature allowing the user to put one caller on hold while other calls are made or answered.
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.
A feature allowing a call to be transferred to another phone
A feature that provides audible or visual indicators to let a single-line-phone user know that she has another call waiting for her.
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.
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.
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.
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).
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.
Card Information Services. A PCMCIA setup protocol.
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.
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.
Cellular Digital Packet Radio.
In communications and networking, a fixed-size packet of data. In cellular telephone systems, a geographic area.
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.
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).
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.
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.
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.
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.
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.
A government-regulated private company offering telecommunications services or communications facilities to the general public.
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.
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.
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.
Clear To Send. This is when the modem lets the other computer know that it can send information to the other computer.
The method of flow control that uses the CTS and RTS signals. It is built into the hardware, not software.
Data Access Arrangement. A device used to connect modems to the switched telephone network.
(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.
Data Circuit Terminating Equipment. Sets up and maintains a data connection link over a communications medium. For example, a modem.
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.
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.
The signaling and data transmission channel (specified in ISDN standards) used to transmit network control signals for setting up phone calls.
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.
A system using discrete numbers to represent data. In computer systems, these are the numbers 0 and 1 (for binary).
Equipment used to set up pathways between users for transmission of digital signals.
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.
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.
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.
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
Electrically Erasable Programmable Read-Only Memory.
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. The ability of a modem to notice errors in transmission, and to resend incorrect data.
European Telecommunications Standards Institute.
European Conference on Computers, Freedom, and Privacy.
European Strategic Program for Research in Information Technologies.
A popular local area data communications network, originally developed by Xerox Corp., which accepts transmissions from computers and terminals.
Transmission lines, switches and other physical components used to provide telephone service.
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.
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
Computer security that attempts to keep crackers out.
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.
A communications system or channel capable of simultaneous transmission in two directions. See Duplex.
A network element interconnecting two otherwise incompatible networks, network nodes, subnetworks or devices.
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.
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.
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.
A communications channel allowing alternating transmission in two directions, but not in both directions simultaneously.
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.
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.
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.
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.
The International Standards Organisation, the body responsible for setting world technical standards. It is based in Geneva, Switzerland.
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.
Last edited by devilsoul; 27th Apr 2011 at 16:50.
A socket, hole or opening mounted on a wall, switchboard or panel, into which a plug connector can be inserted to complete a connection.
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.
The communications channel, usually a physical line, between the subscriber's location and his local central office. Also known as the subscriber loop.
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.
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.
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.
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.
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.
A GUI (Graphical User Interface) for accessing the hypertext WWW (World Wide Web) on the Internet.
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.
Memorandum of Understanding, the GSM body that overseas GSM standards and implementation around the world. It comprises operators and some manufacturers.
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.
A communications channel capable of serving several devices, or users, at once
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.
An abbreviated form of the word multiplexer.