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4B/5B
The physical layer (PHY) coding scheme for FDDI.
802.1 IEEE
A set of standards for governing the OSI Data Link layer and the OSI physical layer. For example, 802.1d is the standard for bridging between the LAN standards
802.2 IEEE
Standards that govern the Logical Link Control (LLC) within the Data Link layer of the OSI model. LLC frames carry user infobetween two stations. These standards are common across the various lower level standards within the Data Link and the Physical layers.
A
adapter
A device, usually in the form of a user interface card, that physically connects an endstation to the network medium; for example, twisted pair, coaxial, fiber.
ANSI (American National Standards Institute)
Organization which coordinates, develops, and publishes standards used in the United States.
Application layer
The seventh layer in the OSI model for data communications. It defines protocols for user or application programs.
ARP (Address Resolution Protocol)
A TCP/IP protocol used to dynamically translate the IP address of a network host to its LAN hardware (MAC) address. This action is limited to LANs that support hardware broadcasts.
Assert
A signal is asserted by driving it to a logical true state. For positive-true signals this state is high logic voltage, and for negative-true signals this state is the low logic voltage.
attenuation
Signal power lost in a transmission medium as the signal travels from sender to receiver.
B
backbone
A network configuration that connects LANs into an integrated network.
bandwidth
Bandwidth typically indicates the data transmission capacity of a network through a given circuit. Generally, the greater the bandwidth, the more information can be sent through a circuit during a given amount of time.
baud
Measurement of signaling speed indicating line changes per second, where line changes can represent one or more bits. The baud is equal to bits-per-second only for line changes representing a single bit.
beacon
A special frame used by media access control to announce to the other stations that the ring is broken. The resulting action attempts to restructure the network to account for the probable fault.
bridge
An internetworking device used to connect two or more computer networks and to forward packets among the networks. Bridges operate at the Link layer of the OSI model.
Bus Latency
Elapsed time from bus master request until bus master is given control of the bus.
bypass
The ability of a station to be optically or electronically isolated from the network while maintaining the integrity of the ring.
C
CFM (Configuration Management)
That portion of the Connection Management (CMT) within the Station Management (SMT) function of an FDDI station that provides for the configuration of PHY and MAC entities within a node.
claim process
A technique used to determine which station will initialize the FDDI ring.
CMT (Connection Management)
That portion of the Station Management (SMT) function within an FDDI station that controls the insertion, removal, and connection of the PHY and MAC entities within that station.
concentrator
An FDDI node that provides attachment points (through M ports) for stations that are not connected directly to the dual ring. The concentrator is the focal point of the dual ring of trees topology.
counter-rotating ring
An arrangement where two signal paths, whose directions are opposite, exist in a ring topology.
CPU (Central Processing Unit)
A computer's main microprocessor chip.
CRC (Cyclic Redundancy Check)
An error checking procedure in which bytes at the end of a frame are used by the receiving node to detect a transmission problem.
D
DAC (Dual Attachment Concentrator
A concentrator that offers two connections to the FDDI network capable of accommodating the FDDI dual (counter-rotating) ring, and additional ports for the connection of other concentrators or FDDI stations.
DAS (Dual Attachment Station)
An FDDI station that offers two connections to the FDDI dual counter-rotating ring.
Differential Manchester encoding
A signaling method that encodes clock and data information into bit symbols. Each bit symbol is divided into two halves, where the second half is the inverse of the first half. A zero is represented by a polarity change at the start of the bit time; a one is represented by no polarity change at the start of the bit time.
DMA (Direct Memory Access)
A fast method of moving data between two processor subsystems without processor intervention.
DMA Controller
Provides control of the larger part of the system's DMA (Direct Memory Access) facility. The DMA controller responds to requests from the DMA device and provides address and control signals to the memory slaves and DMA device.
DMA Device
The DMA device is typically located on a peripheral board on the EISA or ISA bus. The DMA device initiates DMA transfers, which are controlled by signals generated by the system DMA controller. The DMA device either presents or receives data during a DMA transfer and uses several signals to inform the DMA controller of the staus of the transfer.
downstream
A term that refers to the relative position of two stations in a ring. A station is downstream of its neighbor if it receives the token after its neighbor receives the token.
dual homing
A method of cabling concentrators and stations that permits an alternate or backup path to the dual ring in case the primary connection fails. Can be used in a tree or dual ring of trees configuration.
dual ring
An FDDI network topology that uses two redundant rings to overcome fiber-optic failures between two nodes.
dual ring of trees
A topology of concentrators and nodes that cascade from concentrators on a dual ring.
E
ECM (Entity Coordination Management)
That portion of the Connection Management (CMT) within the Station Management (SMT) function of an FDDI station that provides for controlling bypass relays, signaling to PCM (Physical Connection Management) that the medium is available, and coordinating trace functions.
encapsulating bridge
A proprietary hardware device that encapsulates packets into specialized frames, usually by adding a header and a trailer to the frame.
encode
The act of changing data into a series of electrical or optical pulses that can travel efficiently over a medium.
extended LAN
A collection of local area networks (similar or dissimilar) interconnected with a bridge.
F
FDDI (Fiber Distributed Data Interface)
An ANSI standard (X3T9.5) for 100 Mbps LANs based on the token-passing access method. It is often used to bridge several Ethernet segments at high speed.
fiber optic cable
A transmission medium designed to transmit digital signals in the form of pulses of light.
fiber optics
The technique of using fiber optic transmitters, receivers, and cables for the transmission of data.
Float
Signal is placed in the high impedance state.
fragment
In FDDI, pieces of a frame left on the ring; caused by a station stripping a frame from the ring.
fragmentation
A process in which large frames from one network are broken up into smaller frames that are compatible with the frame size requirements of the network to which they will be forwarded.
frame
A Protocol Data Unit (PDU) transmitted between cooperating MAC entities on an FDDI ring, consisting of a variable number of bytes and control symbols.
G
graded index
A characteristic of fiber optic cable in which the core refraction index is varied so that it is high at the center and matches the refractive index of the cladding at the core-cladding boundary.
H
header
Control information added at the data source to allow data to reach its destination. At the destination, layers corresponding to those at the source that created the header read and remove it, so that only the data reaches the final destination.
host
Generally, any computer on a network.
Host CPU
The main system processor. The host CPU typically has its own local bus allowing the CPU to access cache or local memory without using the EISA bus. The host CPU accesses the EISA bus like any other bus master, with the exception of a few special features. The data size of the host CPU does not determine the EISA bus size; the CPU can have an 8-, 16-, or 32-bit data bus and still access the 16- or 32-bit EISA bus.
host name
A unique name that identifies each host machine on a network.
I
ICMP (Internet Control Message Protocol)
An integral part of the Internet Protocol (IP) that handles error and control messages. Specifically, gateways and hosts use ICMP to send reports of problems with datagrams back to the original source of the datagram. ICMP includes an echo request/reply used to test whether a destination is reachable or responding.
IEEE (Institute of Electrical and Electronic Engineers)
An information exchange organization. As part of its various functions, it coordinates, develops, and publishes network standards for use in the United States, following ANSI rules.
Inter-frame gap
The interval between frames on the network media. It is defined by FDDI standards to prevent one frame from becoming confused with the next.
IP (Internet Protocol)
A network layer protocol that contains addressing and control information to allow packets to be routed over dissimilar networks.
ISO (International Standards Organization)
An international body that creates networking standards, including the Open Systems Interconnection (OSI) model.
K
KB
Kilobytes. 1024 bytes.
L
LAN (Local Area Network)
A data communications network that spans a limited geographical area. The network provides high bandwidth communication over coaxial cable, twisted pair, fiber, or microwave media. It is usually owned by the user.
local
Local refers to files and devices, such as disk drives, that are attached to or on your machine.
logical ring
The circular path a token follows in an FDDI network made up of all the connected MAC sublayers. The physical topology can be a dual ring of trees, a tree, or a ring.
M
MAC (Media Access Control)
The Data Link layer in the ISO model that describes how devices share access to a network. Ethernet, token-ring, and FDDI are MAC layer specifications. Wiring hubs deal primarily with MAC layer equipment.
Manchester encoding
A signaling method by which clock and data bit information can be combined into a single, self-synchronizable data stream. A transition takes place in the middle of each bit time. A low-to-high transition represents a one; a high-to-low transition represents a zero.
Mbps
Megabits (1,048,576 bits) per second.
MIB (Management Information Base)
A set of variables that describe how data is stored, monitored, and managed. MIB-I and MIB-II are revisions of the database used in a TCP/IP network. The original MIB was renamed to MIB-I when the MIB-II was defined.
MIC (Media Interface Connector)
An optical fiber connector pair that links the fiber media to the FDDI node or another cable. The MIC consists of two halves. The MIC plug terminates an optical fiber cable. The MIC receptacle is associated with the FDDI node.
multicast
A technique that allows copies of a single packet or cell to be passed to a selected subset of all possible destinations.
multimode
A large-core (62.5 micron) optical fiber through which multiple modes will propagate.
N
network
An interconnection of multiple stations or systems that are able to send messages to or receive messages from one another.
Network layer
Layer 3 in the OSI model; permits communications between network nodes in an open network.
NIF (Neighborhood Information Frame)
Special frames used by the SMT Frame Services within the Station Management (SMT) function of an FDDI station that periodically announce their addresses to downstream neighbors. Each station in the ring makes such an announcement every 30 seconds by sending a NIF that uses Next Station Addressing (NSA), a special addressing mode that permits a station to send a frame to the next station on the token path without knowing the address of that station. This information can be used to create a logical ring map for the order in which each station appears within the ring.
NMS (Network Management Station)
The system responsible for managing a network or a portion of a network. The NMS communicates to network management agents which reside in the managed node using a network management protocol.
node
A device, such as a station or concentrator, connected to a network.
NRZ (Nonreturn to Zero)
A data transmission technique where a polarity level, high or low, represents a logical 1 or 0.
NRZI (Nonreturn to Zero Invert on Ones)
A data transmission technique where a polarity transition from low to high, or high to low, represents a logical 1. The absence of a polarity transition represents a 0.
NSA (Next Station Addressing)
A special addressing mode in FDDI networks that permits a station to send a frame to the next station on the token path without knowing that station's address.
O
optical receiver
An opto-electronic circuit that converts an incoming optical signal to an electrical signal, typically a photodetector.
optical transmitter
An opto-electronic circuit that converts an electrical signal to an optical signal, typically a light emitting diode or a laser diode.
OSI Model (Open Systems Interconnection)
The 7-layer protocol model defined by the International Standards Organization (ISO) for data communications.
P
packet
Data information that is grouped and transmitted together, such as messages, commands, and control codes.
PCM (Physical Connection Management)
That portion of the Connection Management (CMT) within the Station Management (SMT) function of an FDDI station that manages the physical connect between adjacent PHYs. This includes the signaling of the connection type, link confidence testing, and the enforcement of connection rules.
PDU (Protocol Data Unit)
The unit of data transfer between peer layer entities. It may contain control information, address information, and/or data (for example, a Service Data Unit from a higher layer entity). A valid PDU is at least 24 bits in length. The FDDI MAC PDUs are tokens and frames.
peer-to-peer
Assigning of communications tasks so that data transmission between logical groups or layers in a network architecture is accomplished between entities in the same sublayer of the OSI model.
PHY (Physical Layer Protocol)
A standard protocol that defines symbols, line states, clocking requirements, and the encoding of data for transmission.
Physical layer
Layer 1 in the OSI model; defines and handles the electrical and physical connections between systems. The physical layer can also encode data into a form that is compatible with the medium (coaxial, twisted pair, fiber, and so on).
PING (Packet Internet Groper)
A TCP/IP protocol facility used to test the reachability of destinations by sending an ICMP (Internet Control Message Protocol) echo request and waiting for a reply.
PMD (Physical Layer Medium Dependent)
A standard that defines the medium and protocols to transfer symbols between PHYs.
point-to-point
Transmission of data between two nodes where one node is the sender and the other node is the receiver.
Presentation layer
Layer 6 in the OSI model; details protocols governing data formats and conversions.
propagation delay
The time it takes for a signal to travel across the network.
protocol
A set of rules and conventions that govern the exchange of information between communicating parties on a network.
R
reconfiguration
The operation by which a station determines the location of a fault and isolates it by utilizing the redundancy of the dual FDDI ring.
repeat frame
The operation of repeating a group of symbols on the network in exactly the same manner they were received by the station.
repeater
A level 1 hardware device that performs the basic actions of restoring signal amplitude, waveform, and timing of signals, before transmission onto another network segment.
ring
Connections between two or more stations that form a circular topology.
RMT (Ring Management)
That portion of the Station Management (SMT) function within an FDDI station that receives status information from the Media Access Control (MAC) and the Connection Management (CMT). The RMT then reports this status to the SMT and higher-level processes.
router
A level 3 hardware device that uses layer 3 protocols to control network communication between stations and forwards messages to endstations or other routers.
S
SAC (Single Attachment Concentrator)
A concentrator that offers one S port for attachment to the FDDI network and M ports for the attachment of stations or other concentrators.
SAS (Single Attachment Station)
An FDDI station that offers one S port for attachment to the FDDI ring.
services
A set of functions proved by one OSI/ISO layer or sublayer entity, for use by a higher layer or sublayer entity or by management entities.
Session layer
Layer 5 in the OSI model; defines protocols governing communications between applications.
SIF (Station Information Frame)
Special frames used by the SMT Frame Services within the Station Management (SMT) function of an FDDI station that contain more information about the station's configuration and characteristics than the associated Neighborhood Information Frame (NIF). This information can be used to create a physical ring map that shows the position of each station in both the token path and the network topology.
single mode
A small-core (9 micron) optical fiber through which only one mode can propagate.
Slave
A memory or I/O device that uses EISA control signals to interface to the bus.
Slot Specific Signal
Each connector has a unique variant of the signal (instead of a single signal that is bused to all connnectors).
SMT (Station Management)
An entity within a network station on an FDDI ring that monitors station activity and exercises control over station activity. The standard defines how to manage the Physical Layer Medium Dependent (PMD), the Physical Layer Protocol (PHY), and the Media Access Control (MAC) portions of FDDI.
SMT Frame Services
That portion of Station Management (SMT) that provides the means to control and observe the FDDI network. The service uses Neighborhood Information Frames (NIF) and Station Information Frames (SIF) to pass an announcement, a request, and the response to a request.
SNMP (Simple Network Management Protocol)
A high level standards-based protocol for network management, usually used in TCP/IP networks. An SNMP monitor controls and measures the activities of SNMP agents that are embedded in nodes and network devices on the network. SNMP relies on Management Information Bases (MIBs) embedded in the network resources to monitor and control the network's topology.
spanning tree
A method of creating a loop-free logical topology on an extended LAN. Formation of a spanning tree topology for transmission of messages across bridges is based on the industry standard spanning tree algorithm defined in IEEE 802.1d.
station
An addressable node on the network capable of transmitting and receiving data. In an FDDI ring, the station can repeat data. A station has at least one instance of SMT, at least one instance of PHY and PMD, and an optional MAC entity.
stuck beacon
The condition where a station is locked into sending continuous beacon frames.
T
TCP/IP (Transmission Control Protocol/Internet Protocol)
A set of communications protocols that define how different types of computers talk to each other. It is the standard architecture for internetworking multiple organizations, and the common link that ties the huge Internet together.
token
A bit pattern consisting of a unique symbol sequence that circulates around the ring following a data transmission. The token grants stations the right to transmit.
token holding timer
A timer that controls the amount of time a station may hold the token in order to transmit asynchronous frames.
token passing
A method where each node, in turn, receives and passes on the right to use the channel. The nodes are usually configured in a logical ring.
Token Ring
A network topology utilizing a token-passing media access protocol in a ring topology. 100 Mbps FDDI and ANSI 802.5 4- and 16-Mbps Token Ring are token ring technologies.
trace
A diagnostic process to recover from a stuck-beacon condition. The fault is localized to the beaconing MAC and its upstream neighbor MAC.
Transport layer
Layer 4 in the OSI model; defines protocols governing message structure and some error checking.
TRT (Token Rotation Timer)
A clock that times the period between the receipt of tokens.
TTP (Timed-Token Protocol)
The rules defining how the target token rotation time is set, the length of time a station can hold the token, and how the ring is initialized.
TTRT (Target Token Rotation Time)
The value used by the MAC receiver to time the operations of the MAC layer. The TTRT value varies, depending on whether or not the ring is operational.
TVX (Valid Transmission Timer)
A timer that times the period between valid transmissions on the ring; used to detect excessive ring noise, token loss, and other faults.
U
upstream
A term that refers to the relative position of two stations in a ring. A station is upstream of its neighbor if it receives the token before its neighbor receives the token.
UTP (Unshielded Twisted Pair)
Type 3 cable with one or more twisted pairs where the wiring is not protected from electromagnetic and radio frequency, but covered with plastic or PVC.
W
WAN (Wide Area Network)
A network spanning a large geographical area that provides communications among devices on a regional, national or international basis.
workgroup
A network configuration characterized by a small number of attached devices spread over a limited geographical area.
workstation
A networked computer typically reserved for end-user applications.
X
X3T9.5 ANSI
The standard specification for an FDDI network operating at 100 Mbps in a ring topology that can extend to hundreds of stations over tens of kilometers without degrading the system.
Source:docs.hp.com/en/J3703-90004/go01.html?btnNext=next%A0%BB
Showing posts with label Glossaries. Show all posts
Showing posts with label Glossaries. Show all posts
Friday, November 6, 2009
Tuesday, October 27, 2009
Telecommunications Glossary
Select the first letter of the word from the list below to jump to appropriate section of the glossary. If the term you are looking for starts with a digit or symbol, choose the '#' link. Many terms contain Hyperlinks to appropriate sites.
A B C D E F G H I J K L M N O P Q R S T U V W X Y Z #
A
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.
Analogue
Analogue refers to signals that can represent an infinite range of numbers, as opposed to digital which can only be distinct whole numbers. Analogue data often comes from measurements, like a sine wave. The sound a modem makes over the phone is analog since it can be any of a number of different frequencies. The fixed-line networks usually transfer analogue data and fax. The GSM networks are 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.
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 Transmission
Transmission method in which the intervals between transmitted characters may be unequal of length. Transmission is controlled by start and stop bits at the beginning and end of each character. This way, if there is line noise, the modem can find out right away where the next byte should start. [See Synchronous communication].
AT command
Any instructions sent to a modem that begin with "AT". See also Hayes AT command set.
AT command set
See Hayes AT command set.
Attention characters
The letters "AT", which get the modem's attention that you are about to send it a command. [See also Hayes AT command set].
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.
B
Bandwidth
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.
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. [See also bps].
BFT
Binary File Transfer
Billion Rand
What it costs to start a cellular network
Bit
A Binary digIT. It is a number in base 2 (binary), which means that it can only be a 0 or a 1. It is used in the expres-sion `bits per second'. [See also byte].
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. [See also baud].
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
A group of 8 bits. It usually represents one character.
C
CCITT
Consultative Committee International on Telephones and Telegraphy. Used to set standards for modems. Replaced by the ITU.
Card Services
DOS and Windows 3.1x users must have Card Services enabled to use their computer's PCMCIA slot(s). Card Services simply allows DOS/Windows 3.1 to see and set up the computer's PCMCIA slot. 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. You can however download it here.
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.
Carrier Detect Threshold
A way of measuring how well a modem can detect valid data over noisy phone lines. It is measured in negative dBm's (decibel-milliwatts). The bigger the number (the more negative) the better. For example,45 dBm is better than40 dBm.
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.
CLIR
Caller Line ID Restriction. The ability to block someone who you're calling from seeing your number.
CDPR
Cellular Digital Packet Radio
Cell
The receiver/transmitter a GSM phone connects to; the equivalent of the base station of a cordless phone. A cell can support a number of simultaneous calls.
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.
CDMA
Code Divison Multiple Access. A digital cellular technique invented by Qualcomm.
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.
Communications 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.
Compatible
When one object can work just like another. Although the term is usually used with computers, it is often used with modems. Many modems are compatible with other popular modems.
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. [See also archive, data compression].
CODEC
COmpressor/DECompressor, the chip inside every digital GSM cellphone that allows the cellphone to tranmsit voice data at high efficiency and speed across the GSM cellular network. The CODEC will trip redundant voice data like when neither party is talking allowing more effcient use of scarse bandwidth.
CEPT
Conference of European Post and Telecommunications, the European telecommunications authority.
Cracker
From hacker and safe cracker. A hacker who breaks into computers
CTS
Clear To Send. This is when the modem lets the other computer know that it can send information to the other computer. [See also Flow Control, Return To Send].
CTS/RTS
The method of flow control that uses the CTS and RTS signals. It is built into the hardware, not software. [See also CTS, RTS, flow control].
D
DAA
Data Access Arrangement. A device used to connect modems to the switched telephone network.
Data over GSM
Send digital data over the digital GSM networks. Click here for a tutorial on data and fax transmission over GSM.
DCE
Data Circuit Terminating Equipment. Sets up and maintains a data connection link over a communications medium. For example, a modem.
Data Compression
Some modems have the capability to 'squash' data so that it takes up less space. When another modem (that also has this capability) receives the data, it 'unsquashes' the data to its original form. By using data compression, a modem can send information faster. It's a lot like shorthand--all the information is still there, but it takes less space and is quicker. [See also MNP-5, V.42bis].
.
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. [See also bps].
dBm
Decibel refers to one milliwatt. This is used to measure certain levels, such as transmit level.
DSA
Data Services Adapter, an alternative interface to PCMCIA for connecting to a fax or data terminal. The Siemens S1 uses a DSA
Digital
A system using discrete numbers to represent data. In computer systems, these are the numbers 0 and 1 (for binary). [See also Analogue].
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)
DTE
Data Terminal Equipment. This is computer equipment which is not directly responsible for communicating, for example, the computer itself and printers. [See also DCE].
DTMF
Dual Tone Multi-Frequency. This is used in tone dialing. It is a method where 2 distinct tones are sent for each digit dialed.
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.
E
EDI
Electronic Data Interchange. Commonly transferred by Internet or X.400 networks
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.
Error Correction
Error Correction. The ability of a modem to notice errors in transmission, and to resend incorrect data. [See also MNP 1-4, LAPM, V.42].
ETSI
European Telecommunications Standards Institute.
ECFP
European Conference on Computers, Freedom, and Privacy.
E-mail
Electronic mail. Messages that are sent to individual people. You choose who to send the message to and only that person receives the message.
ESPRIT
European Strategic Program for Research in Information Technologies.
Error
When there is line noise and one or more characters are changed. This is especially noticeable when downloading or uploading a program. In this case the error must be detected, and the data must be re-sent.
F
FAQ
Frequently Asked Questions.
Firewall
Computer security that attemps to keep crackers out.
Flame
To write emotional remarks on electronic mail.
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. [See also Xon/Xoff, CTS/RTS].
Full Duplex
A channel providing simultaneous transmission in both directions.
G
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.
GSM
GSM originally stood for Groupe Speciale Mobile but has been anglicised to Global System for Mobile Communications, an international digital cellular standard. South Africa was one of the first to implement Phase 2 of GSM.
Click here for a brief history of GSM.
H
Half Duplex
A channel which signals in both directions, but not 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.
Hayes compatible
Any modem which operates in the same way as the modems developed by Hayes.
Hertz
A unit of frequency, which equals cycles per second.
I
Interactive Manual
A Windows-based modem control and diagnostic program bundled free with each Option 2-in-1 modem. Here you can alter all Hayes AT commands using icons! Just click on the appropriate icon, and the Interactive Manual will instantly alter the modem's settings. You can also change the modem's settings to conform to the PTT specifications of different countries.
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.
IWU
InterWorking Unit. This is the network "modem" where all the digital to analogue (and visa versa) conversions take place within the digital GSM networks
J
K
L
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.
M
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.
Modulation
A process whereby a signal is transformed from its original form into a signal that is more suitable for transmission over the medium between transmitter and receiver.
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.
MNP normal mode
This is the more common mode used with modems that have MNP capability, where the speed from the computer to the modem can be higher than the connection between the modem and the remote modem. This mode uses buffering to prevent lost data.
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.
N
NCAIR
National Center for Automated Information Research.
Network Operators
The folks who install and maintain GSM cellular networks. Click here to see a list of GSM operators around the world. Click here to see the South African network operators.
Non-Transparent Cellular Data
Non Transparent phones use a special error correction technique called RLP. Transparent phones data not incorprate the RLP error corerction techniqure and their data MIGHT be corrupted.
O
P
PABX
Private Branch Exchange. This is the telephone system that many offices have, allowing extensions for each telephone, and a connection to the main telephone system.
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. [See also 8-N-1].
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.
PCMCIA
A credit card sized card that generally plugs into a notebook computer. It conforms to the Personal Computer Memory Card International Association spec. Now known as PC Cards.
PSK
Phase Shift Keying. In this method of modulation/demodulation, there are two frequencies used (usually 1200 hertz and 2400 hertz). There are 4 different phase angles (0, 90, 180, and 270 degrees), representing dibits 00, 01, 10, and 11. This is usually used for 1200bps transmission. Note that the baud rate using PSK is really 1/2 of the bps rate, since 2 bits are sent at a time instead of one. [See also modulation].
PSTN
Public Switched Telephone Network. This is the regular phone lines that just about everybody uses.
Phreaker
Aperson who spends a lot of time trying to find out as much as possible about the telephone company [like South Africa's TELKOM], and how it works. They often try to find out ways to make long distance calls for free. Some steal calls from telephone credit card users, some steal calls from the phone company directly, and others don't make "free" long distance calls. They are sometimes confused with hackers.
PKZIP
The program which will create an archive with the extension "ZIP". It is one of the most popular archive programs.
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.
Q
R
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
RACE
Research and Development in Advanced Communication in Europe.
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. With Option modems, this is the ATZ command.
RJ-11
This is a normal phone jack. The older South African plugs have a 3-prong connector. All Option modems sold in South Africa have this RJ-11-to-3-prong adapters.
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. [See also flow control, CTS].
S
Serial Transmission
A method of transmitting data in which bits are sent sequentially.
SIG
Special Interest Group. The GSM MoU has many SIGS.
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.
SMS
Short Message Service will display a pager-like 160 character message in the LCD panel on the phone. Your phone must support SMS.
Streaming
When data is sent continuously, without waiting to make sure there are no errors. Transparent mode on GSM is an example of a streaming method faster than non-transparent mode, but unreliable.
T
T1
Trunk 1. A heavy duty telephone line.
T3
Trunk 3. A telephone trunk line.
TDMA
Time Division Multiple Access, the magical technique used by the digital GSM network to squeeze more calls onto one channel by dividing a calling channel into a few "discontinuous" pieces.
Telecommunication(s)
This word has no precise definition, but is frequently used. Its definition ranges from "any form of communication over a distance" to "any communication by electric means" to "two computers 'talking' to each other via modems." Methods of communications that probably are considered telecommunications: telephones, cellphones, TV's and fax machines. The word is used both in singular and plural.
Telecommuting
The idea of company employees working from home, rather than their office. At home, they can communicate with the office (and other entities) by modem or voice calls.
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.
TELNET
A program which lets you access other computer systems through Internet.
Terminal Emulation
When a communications program can simulate the operations of a smart terminal.
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.
Transparent Data Transmission
A method of transmission in which the transmission medium will not recognize control characters or initiate any control function. Transparent-based phones do not utilise any error correction. Thus the data sent and received MIGHT be corrupted unless a greater than two-bar cellphone signal is used (South African conditions). 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.
U
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 also serial, parallel, 16550 UART, 8250 UART, 16450, 16550 UART].
V
V.17
The ITU standard for fax transmission at 14,400bps.
V.21
The international standard, created by ITU, that controls transmission at 300bps.
V.22
The international standard for transmission at 1200bps, created by ITU.
V.22bis
The international standard, created by ITU, that controls data transmission at 2400bps.
V.23
The ITU protocol for transmission of 1200bps one way, 75bps the other way.
V.24
This, combined with V.28 is the ITU standard equivalent to EIA's RS-232C standard. V.24/V.28 has 25 pins, just like the original RS-232C standard.
V.28
Part of V.24.
V.29
The ITU standard for 9600bps half-duplex communications.
V.32
The international standard controlling transmission at 9600bps. It was created by ITU. It has provisions for fallback, if the line is too noisy.
V.32bis
The international standard for 14,400 bps modems, ratified by the ITU.
V.34
The international standard for 28,800 bps modems, ratified by the ITU.
V.42
A standard error control system created by ITU that is in use on many 9600bps modems and some 2400bps modems. It includes LAPM, as well as MNP 2-4.
V.42 compatible
This is a modem that follows all the V.42 specifications, except for LAPM error control (instead it uses MNP).
V.42 compliant
This is a modem which follows all the V.42 specifications, and uses LAPM error control if possible. Otherwise, it will go to MNP error control.
V.42bis
A ITU standard for data compression. It can compress data with about a 3:1 compression ratio, although it can compressup to 4:1 given the right conditions. Any modem with V.42bis also has V.42 error control. [See also Data Compression].
W
W3
World Wide Web
WWW
World Wide Web. A hypertext system set up on the Internet.
Waffle
A DOS program to perform UUCICO.
Winsock
A Windows subroutine library that provides access to the Internet TCP/IP.
WINSOCK.DLL
The actual file containing Winsock.
X
X.25
This is a packet-switching protocol developed by ITU. It is used to carry large amounts of data at fast speeds over leased phone lines.
X.32
This is ITU's 1984 update of X.25, also known as X.25 dialup.
X.400
This is the ITU standard protocol for a global system for the exchange of electronic mail.
X.500
The ITU standard for a directory of the users of the X.400 system.
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).
Xmodem-1K
This is similar to Xmodem/CRC, except it uses blocks of 1024 bytes, rather than 128. It is faster than Xmodem, since it needs to stop less often to check for errors. This is sometimes incorrectly called Ymodem. [See also protocol, Xmodem, Ymodem].
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. [See also flow control, Xon].
Xon
The CTRL-Q character. This will sometimes continue paused information.
Xon/Xoff
The flow control method using the Xon and Xoff characters. It is built into the software, not the hardware.
Y
Z
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.
#
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.
Source: www.cellular.co.za/glossary.htm
A B C D E F G H I J K L M N O P Q R S T U V W X Y Z #
A
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.
Analogue
Analogue refers to signals that can represent an infinite range of numbers, as opposed to digital which can only be distinct whole numbers. Analogue data often comes from measurements, like a sine wave. The sound a modem makes over the phone is analog since it can be any of a number of different frequencies. The fixed-line networks usually transfer analogue data and fax. The GSM networks are 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.
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 Transmission
Transmission method in which the intervals between transmitted characters may be unequal of length. Transmission is controlled by start and stop bits at the beginning and end of each character. This way, if there is line noise, the modem can find out right away where the next byte should start. [See Synchronous communication].
AT command
Any instructions sent to a modem that begin with "AT". See also Hayes AT command set.
AT command set
See Hayes AT command set.
Attention characters
The letters "AT", which get the modem's attention that you are about to send it a command. [See also Hayes AT command set].
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.
B
Bandwidth
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.
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. [See also bps].
BFT
Binary File Transfer
Billion Rand
What it costs to start a cellular network
Bit
A Binary digIT. It is a number in base 2 (binary), which means that it can only be a 0 or a 1. It is used in the expres-sion `bits per second'. [See also byte].
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. [See also baud].
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
A group of 8 bits. It usually represents one character.
C
CCITT
Consultative Committee International on Telephones and Telegraphy. Used to set standards for modems. Replaced by the ITU.
Card Services
DOS and Windows 3.1x users must have Card Services enabled to use their computer's PCMCIA slot(s). Card Services simply allows DOS/Windows 3.1 to see and set up the computer's PCMCIA slot. 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. You can however download it here.
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.
Carrier Detect Threshold
A way of measuring how well a modem can detect valid data over noisy phone lines. It is measured in negative dBm's (decibel-milliwatts). The bigger the number (the more negative) the better. For example,45 dBm is better than40 dBm.
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.
CLIR
Caller Line ID Restriction. The ability to block someone who you're calling from seeing your number.
CDPR
Cellular Digital Packet Radio
Cell
The receiver/transmitter a GSM phone connects to; the equivalent of the base station of a cordless phone. A cell can support a number of simultaneous calls.
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.
CDMA
Code Divison Multiple Access. A digital cellular technique invented by Qualcomm.
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.
Communications 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.
Compatible
When one object can work just like another. Although the term is usually used with computers, it is often used with modems. Many modems are compatible with other popular modems.
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. [See also archive, data compression].
CODEC
COmpressor/DECompressor, the chip inside every digital GSM cellphone that allows the cellphone to tranmsit voice data at high efficiency and speed across the GSM cellular network. The CODEC will trip redundant voice data like when neither party is talking allowing more effcient use of scarse bandwidth.
CEPT
Conference of European Post and Telecommunications, the European telecommunications authority.
Cracker
From hacker and safe cracker. A hacker who breaks into computers
CTS
Clear To Send. This is when the modem lets the other computer know that it can send information to the other computer. [See also Flow Control, Return To Send].
CTS/RTS
The method of flow control that uses the CTS and RTS signals. It is built into the hardware, not software. [See also CTS, RTS, flow control].
D
DAA
Data Access Arrangement. A device used to connect modems to the switched telephone network.
Data over GSM
Send digital data over the digital GSM networks. Click here for a tutorial on data and fax transmission over GSM.
DCE
Data Circuit Terminating Equipment. Sets up and maintains a data connection link over a communications medium. For example, a modem.
Data Compression
Some modems have the capability to 'squash' data so that it takes up less space. When another modem (that also has this capability) receives the data, it 'unsquashes' the data to its original form. By using data compression, a modem can send information faster. It's a lot like shorthand--all the information is still there, but it takes less space and is quicker. [See also MNP-5, V.42bis].
.
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. [See also bps].
dBm
Decibel refers to one milliwatt. This is used to measure certain levels, such as transmit level.
DSA
Data Services Adapter, an alternative interface to PCMCIA for connecting to a fax or data terminal. The Siemens S1 uses a DSA
Digital
A system using discrete numbers to represent data. In computer systems, these are the numbers 0 and 1 (for binary). [See also Analogue].
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)
DTE
Data Terminal Equipment. This is computer equipment which is not directly responsible for communicating, for example, the computer itself and printers. [See also DCE].
DTMF
Dual Tone Multi-Frequency. This is used in tone dialing. It is a method where 2 distinct tones are sent for each digit dialed.
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.
E
EDI
Electronic Data Interchange. Commonly transferred by Internet or X.400 networks
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.
Error Correction
Error Correction. The ability of a modem to notice errors in transmission, and to resend incorrect data. [See also MNP 1-4, LAPM, V.42].
ETSI
European Telecommunications Standards Institute.
ECFP
European Conference on Computers, Freedom, and Privacy.
Electronic mail. Messages that are sent to individual people. You choose who to send the message to and only that person receives the message.
ESPRIT
European Strategic Program for Research in Information Technologies.
Error
When there is line noise and one or more characters are changed. This is especially noticeable when downloading or uploading a program. In this case the error must be detected, and the data must be re-sent.
F
FAQ
Frequently Asked Questions.
Firewall
Computer security that attemps to keep crackers out.
Flame
To write emotional remarks on electronic mail.
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. [See also Xon/Xoff, CTS/RTS].
Full Duplex
A channel providing simultaneous transmission in both directions.
G
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.
GSM
GSM originally stood for Groupe Speciale Mobile but has been anglicised to Global System for Mobile Communications, an international digital cellular standard. South Africa was one of the first to implement Phase 2 of GSM.
Click here for a brief history of GSM.
H
Half Duplex
A channel which signals in both directions, but not 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.
Hayes compatible
Any modem which operates in the same way as the modems developed by Hayes.
Hertz
A unit of frequency, which equals cycles per second.
I
Interactive Manual
A Windows-based modem control and diagnostic program bundled free with each Option 2-in-1 modem. Here you can alter all Hayes AT commands using icons! Just click on the appropriate icon, and the Interactive Manual will instantly alter the modem's settings. You can also change the modem's settings to conform to the PTT specifications of different countries.
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.
IWU
InterWorking Unit. This is the network "modem" where all the digital to analogue (and visa versa) conversions take place within the digital GSM networks
J
K
L
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.
M
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.
Modulation
A process whereby a signal is transformed from its original form into a signal that is more suitable for transmission over the medium between transmitter and receiver.
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.
MNP normal mode
This is the more common mode used with modems that have MNP capability, where the speed from the computer to the modem can be higher than the connection between the modem and the remote modem. This mode uses buffering to prevent lost data.
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.
N
NCAIR
National Center for Automated Information Research.
Network Operators
The folks who install and maintain GSM cellular networks. Click here to see a list of GSM operators around the world. Click here to see the South African network operators.
Non-Transparent Cellular Data
Non Transparent phones use a special error correction technique called RLP. Transparent phones data not incorprate the RLP error corerction techniqure and their data MIGHT be corrupted.
O
P
PABX
Private Branch Exchange. This is the telephone system that many offices have, allowing extensions for each telephone, and a connection to the main telephone system.
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. [See also 8-N-1].
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.
PCMCIA
A credit card sized card that generally plugs into a notebook computer. It conforms to the Personal Computer Memory Card International Association spec. Now known as PC Cards.
PSK
Phase Shift Keying. In this method of modulation/demodulation, there are two frequencies used (usually 1200 hertz and 2400 hertz). There are 4 different phase angles (0, 90, 180, and 270 degrees), representing dibits 00, 01, 10, and 11. This is usually used for 1200bps transmission. Note that the baud rate using PSK is really 1/2 of the bps rate, since 2 bits are sent at a time instead of one. [See also modulation].
PSTN
Public Switched Telephone Network. This is the regular phone lines that just about everybody uses.
Phreaker
Aperson who spends a lot of time trying to find out as much as possible about the telephone company [like South Africa's TELKOM], and how it works. They often try to find out ways to make long distance calls for free. Some steal calls from telephone credit card users, some steal calls from the phone company directly, and others don't make "free" long distance calls. They are sometimes confused with hackers.
PKZIP
The program which will create an archive with the extension "ZIP". It is one of the most popular archive programs.
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.
Q
R
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
RACE
Research and Development in Advanced Communication in Europe.
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. With Option modems, this is the ATZ command.
RJ-11
This is a normal phone jack. The older South African plugs have a 3-prong connector. All Option modems sold in South Africa have this RJ-11-to-3-prong adapters.
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. [See also flow control, CTS].
S
Serial Transmission
A method of transmitting data in which bits are sent sequentially.
SIG
Special Interest Group. The GSM MoU has many SIGS.
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.
SMS
Short Message Service will display a pager-like 160 character message in the LCD panel on the phone. Your phone must support SMS.
Streaming
When data is sent continuously, without waiting to make sure there are no errors. Transparent mode on GSM is an example of a streaming method faster than non-transparent mode, but unreliable.
T
T1
Trunk 1. A heavy duty telephone line.
T3
Trunk 3. A telephone trunk line.
TDMA
Time Division Multiple Access, the magical technique used by the digital GSM network to squeeze more calls onto one channel by dividing a calling channel into a few "discontinuous" pieces.
Telecommunication(s)
This word has no precise definition, but is frequently used. Its definition ranges from "any form of communication over a distance" to "any communication by electric means" to "two computers 'talking' to each other via modems." Methods of communications that probably are considered telecommunications: telephones, cellphones, TV's and fax machines. The word is used both in singular and plural.
Telecommuting
The idea of company employees working from home, rather than their office. At home, they can communicate with the office (and other entities) by modem or voice calls.
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.
TELNET
A program which lets you access other computer systems through Internet.
Terminal Emulation
When a communications program can simulate the operations of a smart terminal.
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.
Transparent Data Transmission
A method of transmission in which the transmission medium will not recognize control characters or initiate any control function. Transparent-based phones do not utilise any error correction. Thus the data sent and received MIGHT be corrupted unless a greater than two-bar cellphone signal is used (South African conditions). 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.
U
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 also serial, parallel, 16550 UART, 8250 UART, 16450, 16550 UART].
V
V.17
The ITU standard for fax transmission at 14,400bps.
V.21
The international standard, created by ITU, that controls transmission at 300bps.
V.22
The international standard for transmission at 1200bps, created by ITU.
V.22bis
The international standard, created by ITU, that controls data transmission at 2400bps.
V.23
The ITU protocol for transmission of 1200bps one way, 75bps the other way.
V.24
This, combined with V.28 is the ITU standard equivalent to EIA's RS-232C standard. V.24/V.28 has 25 pins, just like the original RS-232C standard.
V.28
Part of V.24.
V.29
The ITU standard for 9600bps half-duplex communications.
V.32
The international standard controlling transmission at 9600bps. It was created by ITU. It has provisions for fallback, if the line is too noisy.
V.32bis
The international standard for 14,400 bps modems, ratified by the ITU.
V.34
The international standard for 28,800 bps modems, ratified by the ITU.
V.42
A standard error control system created by ITU that is in use on many 9600bps modems and some 2400bps modems. It includes LAPM, as well as MNP 2-4.
V.42 compatible
This is a modem that follows all the V.42 specifications, except for LAPM error control (instead it uses MNP).
V.42 compliant
This is a modem which follows all the V.42 specifications, and uses LAPM error control if possible. Otherwise, it will go to MNP error control.
V.42bis
A ITU standard for data compression. It can compress data with about a 3:1 compression ratio, although it can compressup to 4:1 given the right conditions. Any modem with V.42bis also has V.42 error control. [See also Data Compression].
W
W3
World Wide Web
WWW
World Wide Web. A hypertext system set up on the Internet.
Waffle
A DOS program to perform UUCICO.
Winsock
A Windows subroutine library that provides access to the Internet TCP/IP.
WINSOCK.DLL
The actual file containing Winsock.
X
X.25
This is a packet-switching protocol developed by ITU. It is used to carry large amounts of data at fast speeds over leased phone lines.
X.32
This is ITU's 1984 update of X.25, also known as X.25 dialup.
X.400
This is the ITU standard protocol for a global system for the exchange of electronic mail.
X.500
The ITU standard for a directory of the users of the X.400 system.
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).
Xmodem-1K
This is similar to Xmodem/CRC, except it uses blocks of 1024 bytes, rather than 128. It is faster than Xmodem, since it needs to stop less often to check for errors. This is sometimes incorrectly called Ymodem. [See also protocol, Xmodem, Ymodem].
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. [See also flow control, Xon].
Xon
The CTRL-Q character. This will sometimes continue paused information.
Xon/Xoff
The flow control method using the Xon and Xoff characters. It is built into the software, not the hardware.
Y
Z
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.
#
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.
Source: www.cellular.co.za/glossary.htm
Tuesday, October 20, 2009
Telecommunication Glossary
This reference table is provided for your use, so that you may further understand many of the features and benefits provided by CommWorld Northwest and Toshiba Phone Systems.
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.
Source:commworldnw.tripod.com/Glossary.html
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