It's a good time to pray for victims of September 11, 2001 terrorist activities!


    See mega- or micro-.
mega- (M)
micro- (M)

M/MU See Monitor/Matrix Unit.
    Monitor/Matrix Unit (M/MU)

    See microwave (M/W)

    A multiplexor that adapts DS-1 circuits to DS-3 circuits.

See media access control.
media access control (MAC)

machine language
A binary language, consisting of 0s and 1s, used by programmable

machine-oriented code
A code whose words and syntax are designed for use on a specific class
of computers.

A group of frequently used computer commands or routines that are
combined into a single command that are accessed with one or two

mag media
Magnetic data storage such as floppy disk, hard drive, or tape.

magnetic bubble storage
A storage medium composed of a very thin layer of magnetic garnet
material. Under the influence of magnetic external fields, the bubbles
can be maneuvered to represent information bits.

magnetic core
A device that can assume and maintain either of two magnetized
conditions to provide storage, gating, or switching.

magnetic disk
A circular, flat plate with a magnetizable surface layer for data
storage on one or both sides.

magnetic storage
Any device that utilizes the magnetic properties of materials to store

magnetic tape
A tape impregnated or coated with magnetic material upon which data can
be stored by magnetic recording.

A program used by BBS's that allows other BBS's to call, so that mail
and/or files can be transfered automatically between the two.

main crossconnect (MCC)
An element in the EIA/TIA 568 Commercial Building Wiring standard. MCC
consists of the active, passive, and support components that connect
the interbuilding backbone cables between intermediate crossconnects.

main distribution frame (MDF)
The point where outside plant cables terminate and cross connect to
terminal or central office (CO) line equipment.

main PBX
A private branch exchange (PBX) directly connected to a tandem switch
by way of an access trunk group.

main satellite service
A private branch exchange (PBX) feature permitting multi-location
customers to consolidate multiple attendant positions (satellites) at
one location (called the main).

mainstream network management
The network control and diagnostics performed by a host computer that
depends on network functions integrated from end to end.

See metropolitan area network (MAN)

man-machine interface
The interface between an end user and a computer.

management information
The necessary data or program results considered essential for decision
making, with regard to business operations and control.

management information base (MIB)
A database of network management information used by the open system
interconnection (OSI) common management information protocol (CMIP) and
the transmission control protocol/Internet protocol (TCP/IP) simple
network management protocol (SNMP) standard.

management information base-I (MIB-I)
The initial collection of objects and attributes defined by the
transmission control protocol/Internet protocol (TCP/IP) standards.

Management Science America (MSA)
A financial accounting package used in the telecommunications industry.
It includes modules for general ledger, accounts payable, purchasing,
project tracking and fixed assets. It also has a reporting module known
as Information Expert. Information Expert is established by WISC. The
MSA application is supported by WISC. Synonym: direct broadcast

manchester encoding
A signaling method that combines clock and data bit information 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.

manual exchange
An exchange where calls are connected through an operator.

manual originating line
A system where the attendant must complete all outgoing calls. All
other calls are blocked.

manual PBX
A simple private branch exchange (PBX) where all calls, including
intercom, must be routed through an attendant

manual ring down (MRD)
A system where ring signaling is controlled by the user. When not
signaling, an open circuit is present at all times.

manual signaling
A system that sends an audible signal to a designated telephone when a
button is pushed on another telephone.

manual terminating line
A system of lines that requires all calls to be connected by an

manual tie line
A tie line that requires the assistance of an attendant at both ends of
the circuit in order to complete a call.

manufacturing automation protocol (MAP)
An evolving protocol that is becoming an industry standard for
communications among various automation devices in manufacturing

See manufacturing automation protocol (MAP)

See Messaging Application Programming Interface.
Messaging Application Programming Interface (MAPI)

1) The establishment of one-to-one correspondence between two sets of
data. 2) The translation of one group of data into a new set of data.

A European maritime satellite.

market service area
1) Areas analogous to local access transport areas (LATAs), but
frequently of smaller size. Established by state law for regulatory
purposes. 2) Areas not included in Bell operating companies' (BOC's)
LATAs, but treated as LATAs for some purposes under state law.

market sustainable rate of contribution
The level of contribution which leads to the highest sustainable
contribution revenue over the long run (i.e., the level above which
there would be a net revenue loss due to market forces, such as
bypass). (See contribution.)

market-driven local service pricing mechanisms
Refers to the setting of local prices based on the interaction between
customers and suppliers in a competitive market place, recognizing
regulatory constraints (e.g., the CRTC's objective of ensuring the
availability of universal local service at affordable rates). (See
natural market.)
natural market

The submarine cable between Marseilles, France and Palo, Italy.

The submarine cable between Marseilles, France and Tel Aviv, Israel.

See microwave amplification by stimulated emission of radiation (MASER)

A method of transforming one set of data into another while blocking or
excluding some data from this process on the basis of code patterns or

master agent
Someone who employs agents to sell telecom operator services.

master control program
A program that directs the operation of a computer system and its

master file
A relatively permanent file that is an authority for a specific job,
though its contents may change.

master group (MG)
A method in which 240 circuits processed as a unit in a carrier system.

master number hunting The routing pattern in which a call addressed to
a pilot number of a hunt group will connect to the first non-busy
station in the group. If a call is addressed to a specific station in
the hunt group, it will go straight to the station and not hunt to
another station in the group.

master station A telephone system or local area network (LAN) station,
that controls all other stations in the system. In a LAN, this is
generally accomplished through polling.

master terminal A terminal that can communicate with all other
terminals in a network. Only one terminal can be master at any one

master/slave testing
A test method that allows end-to-end testing without a second operator.
A test set (master) at one end controls a test set (slave) at the other
end of the line under test.

A switch used for moving calls from an input to a requested output.

matrix printer
A printer that represents characters in a specific pattern of dots.
Synonym: dot matrix printer

matrix switching
A form of data switching at the heart of ATM, enabling the appropriate
of bandwidth to be available end-to-end for the duration of the session
without contention.

See media access unit (MAU), multistation access unit (MAU), or Medium
Attachment Unit (MAU)

See minimum assignable unit of ownership (MAVO)

See media control architecture (MCA)

See main crossconnect (MCC)

See media control interface (MCI)

Multipoint Conference Service

See multipoint control unit (MCU)

See main distribution frame (MDF)

See multiple-document interface (MDI)

A European public value-added network (VAN) operator.

mean anomaly
The angular distance from the perigee point to the satellites mean
position. Measured in degrees along the orbital plane in the direction
of motion.

mean motion
The number of complete revolutions the satellite makes in one day.

mean time between failure (MTBF)
The average length of time during which a system or component operates
without fault.

mean time to repair
The average time required to correct a fault in a system or component.

measured rate service
A telephone service where charges correspond with line utilization.

measured service
The mechanized interface to the Service Management System (SMS)/800.
Direct computer-to-computer interaction software between an
interexchange carrier (IEC) computer systems and the SMS/800. This is
in contrast with manual "online" or "batch" file processing modes.
Synonym: mechanized generic interface See Service Management System and
responsible organization.
Service Management System (SMS)
responsible organization (RO and resporg)

See multiple exchange carrier access billing (MECAB)

mechanized generic interface
See measured service

1) The transmission paths along which signals pass. For example,
optical fibers, cables, waveguides, radio waves, and so forth. 2)
Information storage techniques such as magnetic tape, magnetic disk,
optical disc, and print.

media access control (MAC)
1) The lower sublayer of the data link layer in the open system
interconnection (OSI) model. MAC is responsible for scheduling, gaining
access, and transmitting and receiving data on the network media. 2) A
generic term for the way in which workstations gain access to
transmission media. The term is most widely used in reference to local
area networks (LAN)s. Synonym: media access controller

Media Access Control driver
A LAN device driver that works directly with the network adapter cards,
acting as an intermediary between the transport driver and the

media access controller
See media access control (MAC)

media access unit (MAU)
A physical device used in Ethernet networks to transmit signals from
the media access controller (MAC) onto the network medium. Synonym:

Media control architecture (MCA)
A specification developed for addressing various media devices from
Macintosh computers.

media control interface (MCI)
Platform independent media specification published by MicroSoft
Corporation and others in 1990. Provides a consistent way to control
devices such as CD-ROMs and video playback units.

media interface connector (MIC) An optical fiber connector pair that
links fiber media to the fiber-distributed data interface (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.

MediaLinx Interactive Inc.
A new company created by Bell Canada and its Stentor partners as part
of their Beacon initiative for the information highway. Launched in
October 1994, MediaLinx Interactive Inc. will seek and develop
interactive and media services and applications. (See information
highway; Section 2: Beacon.)
information highway

1) the material on which data may be represented. 2) The material used
for transmitting telecommunications signals, such as, optical fiber,
cables, water, radio waves.

medium access control (MAC)
A media-specific access control protocol within the the Institute of
Electrical and Electronic Engineers (IEEE) 802 specifications.

Medium Attachment Unit (MAU)
A transceiver (transmitter/receiver) comprising hardware circuitry that
provides the correct electrical or optical connection between the
computer and the Institute of Electrical and Electronic Engineers
(IEEE) 802.3 LAN media. Since MAUs typically support only one type of
network medium, a choice of MAUs is available to support different
media. It detects carrier and collision activity, passing the
information to the Computer. It can be a standalone unit or
incorporated in a circuit board inside the computer,

medium frequency
Frequencies between 300 and 3000 KHz.

Medium Interface Controller (MIC)
An hermaphrodite connector on IBM patch parels specified in 802.5.

medium scale integration
Integrated logic circuits containing functions in between small-scale
and large-scale integration. Medium scale integration usually involves
10 to 100 gates are produced on a silicon chip.

medium speed
Refers to data communications systems operating at and above 2,400 bits
per second up to the speed limit obtainable on a voice grade channel
(i.e., 9,600 bps). (See high speed; low speed.)
high speed
low speed

medium-earth-orbit (MEO)
Orbit paths between 4850 miles and 6425 miles above the earth. These
values are approximations.

meet-me conferencing
A feature allowing a conference of all parties dialing the same number.

meet-me paging
A facility to access voice paging equipment and subsequent automatic
connection after the answered party acknowledges the page. The calling
station goes off hook after paging.

mega- (M)
One million (106) times a specific unit.

member server
A server in a domain that keeps and uses a copy of the domain's user
accounts database but does rot validate logon requests.

See storage

memory address
A computer storage location that is distinguished by its address.

memory dump
A listing of the contents of all or part of a computer storage device.

memory location
A particular site within a computer storage device.

memory management
A program that manages the function of user programs in a
multiprogramming medium.

memory map
A representation of the type of stored data, and where it is located in
a computer's memory.

memory protection
See storage protection

A list of displayed options from which an operator can select the next

See medium-earth-orbit (MEO)

MEO satellite
A satellite based system in medium earth orbit (MEO).

MERS most economical route selection
See least-cost routing (LCR)

An ordered series of characters, words, or symbols intended to convey
information. Message contents generally contain a heading, text, and an
end-of-message symbol, and are delivered as an entity.

message accounting
See station message detail recording.
station message detail recording (SMDR)

message address
The information contained in the message header that indicates the
message destination.

message base
A group of messages on a BBS pertaining to a certain topic..

message circuit
A circuit used for completing telephone calls.

message control packet
The message control information that remains in a message specific
storage area for the duration of its stay in the system.

message feedback
A technique for checking the accuracy of transmission of data. The
received data is returned to the sender for comparison with the
original data.

message format
The rules for establishing parts of a message, such as its header,
address, text, and ending.

Message Handling System (MMS)
The engine underlying an electronic messaging system. Also a
proprietary e-mail integration scheme developed by Action Technologies.

message registration
A telephone system feature, usually employed in hotels, that details
the number of message units contracted by each telephone.

message relay
A private branch exchange (PBX) feature that permits a caller to record
a message and then have it transmitted to another telephone at a
designated time.

message retrieval
The process of searching a log of transmitted messages for a particular
message and sending the located message to the requestor.

message switching
The technique of receiving a message, storing it until the proper
outgoing line is available, then retransmitting it, with no direct
connection between incoming and outgoing lines. Synonyms:
line-switching, and store-and-forward

Message Telephone Service
AT&T's tariffed pricing name for long-distance telephone calls.

message toll service (MTS)
A pay-by-the-minute switched long-distance service. MTS includes
conventional long distance and measured wide area telecommunications
service (WATS).

message unit (MU)
A local toll rate calling plan that is time and distance sensitive.

message unit call
A call made within the calling station's local service area and charged
against the message unit allowance during a fixed billing period.

message unit detail (MUD) study
A report compiled by the local telephone company that details a user's
outgoing calls over a given period.

message waiting
A service, usually found in hotels and large corporations, where a lamp
or other device on a telephone alerts a user, or guest, that a message
has been received and is being held either by a computer, message
center, operator, or receptionist.

One-way communications involving some form of storage or recording

Messaging Application Programming Interface (MAPI)
Microsoft's standard for the applications interface to e-mail. See also

metal oxide semiconductor (MOS)
A type of computer memory utilizing slices of silicon. These silicon
slices require constant electric current for the data to be retained.

metropolitan area network (MAN)
A local area network (LAN) interconnected within roughly a 50 mile
radius. MANs typically use fiber-optic cable to connect various wire
LANs. Transmission speeds may vary from 2 to 100 Mbps. The Institute of
Electrical and Electronic Engineers (IEEE) 802.6 standard specifies the
protocols and cabling for a MAN. However they could be superseded by
asynchronous transfer mode (ATM) protocols.

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metropolitan fiber ring An advanced, high-speed local network that can
also be used to connect businesses and residences directly to a
long-distance carrier's network. A metropolitan fiber ring is an
alternative to the local telecommunications services that they already

metropolitan statistical area (MSA) The top 306 urban areas licensed by
the Federal Communications Commission (FCC) to provide cellular
service. Rural service area (RSA) markets are similar, except for
pertaining to rural locations.

MF See medium frequency, multifrequency, or dual-tone multifrequency.
medium frequency
dual-tone multifrequency (DTMF)

MFJ See Modification of Final Judgement.
Modification of Final Judgement (MFJ)

MG See master group.
master group (MG)

MGI mechanized generic interface See measured service.
measured service

MIB See management information base.
management information base (MIB)

MIB-I See management information base-I.
management information base-I (MIB-I)

MIC See media interface connector.
media interface connector (MIC)

Micro Channel Architecture IBM's peripheral-expansion architecture
developed for the PS/2 computer.

micro floppy
See microdiskette

micro- (M)
One millionth (10-6) of a specific unit.

See micro-mainframe link

micro-mainframe link
A hardware and/or software product that supports communications between
a PC and a host computer. The most common type of link enables the PC
to emulate a terminal supported by the host computer.

Interior located antennas with limited coverage ranges. Microcells are
linked to a standard cell site.

A proprietary bus developed by IBM for its PS/2 computer family's
internal expansion cards. It offers improved performance over ISA-based
machines like the IBM PC/AT.

Microcom Networking Protocol (MNP)
A proprietary error-connecting protocol for modems developed by

See desktop computer

A 3.5 inch magnetic storage medium that can typically store 720 Kbytes
of data. Synonym: micro floppy

The main logic and control component of a microcomputer system, whose
principal elements and execution instructions are generally contained
on a single integrated chip.

The combining of basic, elemental computer operations to create higher
level functions on the computer.

microwave (M/W)
1) An electromagnetic wave between one centimeter and 100 centimeters
(10 Hz) in length. 2) Those frequencies in the super-high-frequency
(SHF) band used for data and voice communications. 3) Electromagnetic
waves in the radio-frequency range of 890 MHz to approximately 30 GHz
that are used for line-of-sight transmission of voice, video, and data.
This is usually in the 2 GHz, 4 GHz, and 6 GHz bands. Synonym:
microwave radio

microwave amplification by stimulated emission of radiation (MASER)
The general class of microwave amplifiers based on molecular
interaction with electromagnetic radiation. The nonelectronic nature of
the maser principle results in very low noise.

microwave radio
See microwave (M/W)

microwave system
A high-capacity transmission system that transmits information via
high-frequency radio signals called microwaves. Initially, microwave
systems offered analogue transmission. Current systems offer digital
transmission and complement fiber optic transmission systems.

MIDI file extension.

See Musical Instrument Digital Interface (MIDI)

US Military Nomenclature for H.320 compatible video conferencing

Military Network (Milnet)
Originally part of Arpanet, Milnet was partitioned in 1984 to make it
possible for military installations to have a reliable network service
while the Arpanet continued to be used for research. Under normal
circumstances, Milnet is part of the Internet.

milli- (m)
One thousandth (10-3) of a specific unit.

See Military Network (Milnet)

See multipurpose Internet mail extensions (MIME)

mini computer
A computer that is larger and more powerful than a typical personal
computer, but smaller than a mainframe.

minimum assignable unit of ownership (MAVO)
The minimum ownership unit in a facility; used especially to designate
the right to use 73,684,656 bps of an optical fiber submarine cable,
which provides 64 Kbps of usable capacity.

minimum investment unit (MIU)
The minimum initial investment unit in a facility; used especially to
designate the right to use one E1 channel in an optical fiber submarine
cable. The owner of an MIU may have the right to assign the right to
use an indefeasible right of use (IRU).

mirrored server
A server that entails the use of two hard disks of similar size, and a
single disk channel over which the disks can be mirrored. All data
written to the primary disk is automatically copied onto the other
disk, with the second disk becoming operational if the primary disk

miscellaneous trunk access
A feature that facilitates access to external and customer-provided
facilities and equipment such as, tie, exchange network, paging, and
code calling.

See minimum investment unit.
minimum investment unit (MIU)

mixed station dialing
The ability to simultaneously use rotary and push-button telephone sets
with all features provided to either type of telephone.

See Multipoint Junction Unit.
Multipoint Junction Unit (MJU)

multi-layer protocol .

See man-machine interface

See Message Handling System (MMS)

See Microcom Networking Protocol (MNP)

MNP Level 10
A Microcom Networking Protocol providing error-correction and
compression for "dirty" telephone lines. See Microcom Networking
Microcom Networking Protocol (MNP)

MNP Level 9
A Microcom networking protocol providing "turbo" mode error-correction
and data compression. See Microcom Networking Protocol.
Microcom Networking Protocol (MNP)

MNP Levels 2, 3, and 4
A Microcom Networking Protocol providing three progressive levels of
error-correcting performance. See Microcom Networking Protocol.

MNP Levels 5 and 7
A Microcom Networking Protocol providing two progressive classes of
data compression compatible with MNP Level 4 error correction. MNP
Level 5 offers 2-to-1 data compression for 1200 bps and higher modems.
MNP Level 7 offers 3-to-1 data compression. See Microcom Networking
Microcom Networking Protocol (MNP)

MNP Levels 6 and 8
A Microcom Networking Protocol providing error correction and
compression protocols for half-duplex modems. See Microcom Networking
Microcom Networking Protocol (MNP)

mobile communications
A wireless form of communication in which voice and data information is
emitted, transmitted and received via microwaves. This type of
communication allows individuals to converse with one another and/or
transmit and receive data while moving from place to place. Some
examples include: cellular and digital cordless telephones; pagers;
telephone answering devices; air-to-ground telecommunications; and
satellite-based communications.

mobile earth station
A portable terminal capable of transmitting, receiving, and processing
data communicated by satellite.

mobile telephone
A portable radiotelephone. See cellular telephone.

mobile telephone exchange (MTE)
A switching center that manages calls in a cellular telephone system.

mobile telephone service (MTS)
Radiotelephone service that provides vehicles with two-way access to
public telephones and other mobile telephone stations. See cellular
cellular telephone

See demodulation

1) The method of operation of a system. 2) In a statistical sense, the
most recent value.

mode of operation
In a given situation, the method of processing data.

See simulation.

A device that modulates and demodulates signals on a carrier frequency,
and provides the interface between digital terminals and analog carrier

Modem Approvals Group
Established in January 1993 to raise awareness of the UK law against
connecting unapproved devices to the PSTN, this group demands a level
playing field in the modem market with better law enforcement or more
open standards.

modem eliminator
A device that can replace a modem in some instances when the distance
to be covered is short. It takes the power it needs to operate from the
transmission line.

modem pooling
A technique that allows a terminal in a private branch exchange (PBX)
system to access outside terminals through various modem groups that
operate at different speeds.

modem sharing unit (MSU)
A device enabling more than one terminal to share a modem.

The person who is in charge of a conference. This person usually has
the task of making sure that users of the conference follow the
conference rules.

Modification of Final Judgement (MFJ)
The agreement between the U.S. Department of Justice and AT&T governing
the breakup of the pre-divestiture Bell system into AT&T and 22 Bell
operating companies (BOCs), and other entities. On August 26, 1982, U.
S. District Court Judge Harold Greene accepted, with modifications, an
AT&T/Justice Department settlement terminating the government's 1974
antitrust suit against AT&T. Judge Greene's decree eliminated the
provisions of the 1956 consent decree that had kept AT&T out of
competitive, unregulated ventures. The MFJ settled the 1974 antitrust
suit and specified the divestiture of AT&T. The MFJ created the seven
regional holding companies (Baby Bells), BOCs, local access transport
areas (LATAs), equal access, and so forth. AT&T retained long-distance
service and its manufacturing business. The restriction that barred
AT&T from entering the computer business was lifted.

A unit that is made up of various subunits that can be combined in a
variety of ways.

The construction of equipment from sub-assemblies having suitability
defined interfaces

The alterations in the characteristics of carrier waves. Modulation is
usually impressed on the amplitude and/or the frequency.

A device that converts a voice or data signal into a transmittable

A discrete and identifiable program unit, hardware, or software.

1) A video display. 2) Any hardware or software that supervises the
operation of a system and indicates any deviation from its standard
operating procedure.

monitor access testing
Nonintrusive circuit testing performed without splitting the circuit to
put the test equipment in-line with the tested signal.

Monitor/Matrix Unit (M/MU)
An optional component in either a DTAU or Mini-DTAU. It performs basic
scanned monitoring of T1 lines.

The task of listening in on other stations in a communications system.

monitoring device
A device to record data on calls placed through a company's telephone
system, including number called, length of calls, and calling location.

monolithic driver
A network device driver that acts as network adapter card driver and
transport protocol driver combined.

See single-mode fiber.
single-mode fiber

morse code
The dot-dash code used in early line-telegraphy. Morse code is still
used by ships at sea that do not have machine codes and MARISAT
satellite antennas installed.

MOS See metal oxide semiconductor.
metal oxide semiconductor (MOS)

most economical route selection (MERS)
least-cost routing

The main circuit board of a computer system.

motion compensation
see motion prediction

Motion Picture Expert Group (MPEG)
The international consortium of hardware, software and publishing
interests dedicated to developing international standards for the
compression of moving video images in digital systems. Similar to
spatial compression of JPEG, but adds frame to frame temporal
compression. Compaction is typically 3 times better than video JPEG.
Produces VCR quality video. MPEGII yields broadcast quality video.

motion prediction
A type of interframe coding used by codecs to compress motion video. By
examining statistics of previous video frame sequences, a prediction of
the motion vector and rate-of-change for an object or group of pixels
in the future is developed for subsequent frames. In H.261, the
estimated vectors must terminate within the image while in H.263, they
may extend outside the image bounds. Important at lower transmit bit
rates, optional in H.261.

motion video
Video that displays real motion by displaying a sequence of images
(frames) rapidly enough that the eyes see the image as a continuously
moving picture.

A small peripheral used in place of a keyboard to control cursor
movement for editing, graphics, and menu-selection functions.

See multiplex (MP)

See Multimedia PC.

See Motion Picture Expert Group (MPEG)

A standard MIDI interface that features its own CPU for processing some
MIDI data without taxing the main computer's resources.

See manual ring down (MRD)

See market service area, or Management Science America (MSA)

See Multi-Station Access Unit.
multistation access (MSAU)

MSO See multiple systems operator.
multiple systems operator (MSO)

MSU See modem sharing unit.
modem sharing unit (MSU)

See mean time between failure (MTBF)

See mobile telephone exchange (MTE)

See mobile telephone service (MTS) or message toll service (MTS)

See mobile telephone exchange (MTE)

See message unit (MU)

The method of encoding audio signals used in U.S. standard 24 channel
pulse code modulation (PCM) systems.

See message unit detail (MUD) study

multi-cast bit
A bit found in the Ethernet addressing scheme that indicates that the
message is to be sent to all stations.

The ability of users, working independently, to simultaneously
communicate with a computer.

A local management interface (LMI) option that allows a frame relay
device to broadcast frames to multiple destinations.

multicast message
A message that is intended for a set of stations on a network.

multicast packets
Packets are addressed to a group of devices on a local area network
(LAN). LAN stations use multicast packets to deliver information to a
specific set of devices, such as routers, servers, hosts, and nodes.

A term applied to systems in which several points are served by the
same circuit.

multidrop circuit
A single circuit or channel that has more than one connection on one
end, such as two offices at one location sharing one line.

multidrop line
A communications channel that interconnects several stations in
different geographical locations. Synonym: multipoint link

A set of consecutive frames in which the relative position of each
frame can be identified.

A signal composed of two or more frequencies.

multifrequency signaling
An inband address signaling method between offices. In this method, 10
decimal digits and 5 auxiliary signals are represented by selecting two
frequencies out of the following group: 700, 900, 1100, 1300, 1500, and
1700 Hz.

A bisynchronous transmission of a varying number of data streams
between user devices and a computer.

multiline hunt group (HML)
A process that rolls over to the next available line if the first line
is busy.

A thick cored (50-200 microns) optical fiber for carrying lightwave
communications along multiple paths.

multiple access
1) The ability of personal computers on a local area network (LAN) to
communicate through a common addressing scheme and contention-based
protocol. 2) The connection of a subscriber or user to two or more
switching centers by separate access lines using a single message
routing indicator or telephone number.

multiple classes of service
Features and restrictions grouped and assigned according to the type
most closely meeting the user's calling pattern and needs.

multiple customer group operator
A private branch exchange (PBX) shared by several companies, with
separate trunks and consoles for each.

multiple exchange carrier access billing (MECAB)
Billing of a jointly provides access service by two or more local
exchange carriers (LECs).

multiple listed directory
A technique that allows for more than one directory number to number
service be listed for a private branch exchange (PBX).

multiple systems operator (MSO)
A company owning multiple cable systems.

multiple trunk groups
A switching system that is capable of being equipped for more than one
group of trunk circuits.

multiple-document interface (MDI)
The Microsoft Windows standard that allows an application to control
multiple documents or views of the same document within the main
application window or workspace.

multiplex (MP)
The transmission of more than one signal over a single communications
channel. Two methods used are: frequency division and time division.

multiplexer (MUX)
A device that combines two or more signals into a single composite data
stream for transmission on a single channel. For example, an M1-3 MUX
combines 28 DS-1s into a DS-3.

A technique used to combine several communications channels into one
facility or transmission path.

A circuit providing simultaneous transmission among three or more
separate points.

multipoint circuit
A circuit that has more than one interexchange carrier (IEC) leg.

multipoint connection
A single channel or circuit interconnecting devices in different
locations. This usually means using polling techniques with each
terminal[terminal a unique address. Also know as a multi-drop line.

multipoint control unit (MCU)
A device that allows video codecs at multiple sites to be linked into a
single session.

Multipoint Junction Unit (MJU)
A unit that links three or more segments of a multipoint circuit at a
DDS hub office.

multipoint line
A communications channel to which more than one terminal is attached.
Only one may transmit at any given time, though several may receive.

multipoint link
See multidrop line

multiport repeater
The center of a star topology network that regenerates signals from one
port and retransmits to all other ports connected to it. Synonym: hub

The simultaneous processing by two or more processors in one computer,
or by two or more computers processing together.

A system possessing two or more communicating processing units.

A technique for handling multiple routines or programs simultaneously
by overlapping or interleaving their execution.

multiprotocol encapsulation
A technique used by routers to encapsulate packets so they can tell
whether it is an Internet protocol (IP), internetwork packet exchange
(IPX), or AppleTalk. protocol. A variety of methods can be used for
this. One method is specified in RFC1490 for frame relay (FR) networks.
Another is specified in RFC1483 for asynchronous transfer mode (ATM)
networks. Most routers allow you to choose one or the other.

multipurpose Internet mail extensions (MIME)
A specification defining interchange of text in languages with
different character sets, and e-mail among many different computer
systems that use Internet mail standards.

multistation access (MSAU)
A wiring concentrator on a Token Ring network that allows devices,
typically eight to 12 Token Ring stations, to be connected to the ring.
Relays in the MAU ensure the integrity of the network when devices are
attached or removed. A Managed Multi-Port/Multi-Station Access Unit has
built-in network management support.

multistation access unit (MAU)
A concentrator used in token-ring networks to connect multiple
stations. The token-ring MAU and an arrangement of internal relays
function as bypass switches and connect stations to form a complete
electrical ring. MAUs can be connected to create larger rings.

The concurrent execution of two or more tasks, or the concurrent use of
a single program that can carry out multiple duties.

multitenant sharing
The ability for multiple user groups to share a telephone system.

The simultaneous processing of more than one message by an application

A software program that supports several users without detriment to any
of them.

Musical Instrument Digital Interface (MIDI)
A digital communications standard that lets electronic musical
instruments and computers communicate with each other. MIDI files are
typically saved with a .MID file extension.

See multiplexer (MUX)

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Created by Jim Needham

İVector Graphics 1995

Revised: February 16, 2011
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