Mbps - Megabits per second (Million bits per second). A measurement for the speed of data transmission. One megabit equals approximately 1,000,000 bits.

MCU - Multipoint Control Unit that can link several videoconferencing systems for multipoint calls.

Message - The Layer 3 information that is passed between CPE and SPCS for signaling.

Metropolitan Statistical Area (MSA) - A term used by government agencies and other organizations. The MSA divides the United States into 306 areas according to population density. Cellular contracts are awarded by MSA.

MIB - Management Information Base. Specifications which contain the format definitions of data fields for remote management by SNMP.

MIPS - Million Instructions Per Second (fixed-point).

MLP - Multi-layer protocol for data (in H.221). MLP data and audio can only be placed in the first 64 kbps channel of a connection. T.120 must use the MLP or HMLP channel.

Mobile Telephone Switching Offices (MTSO) - A cellular CO, for use only within the cellular network. Interacts with cell sites. 

Modem - Modulator-demodulator. Converts digital signals to and from analog.

Modulation - The process of manipulating the frequency or amplitude of a carrier in relation to an incoming video, voice or data signal.

Modulator - A device which modulates a carrier. Modulators are found as components in broadcasting transmitters and in videoconference transponders.

Mosquitos - Artifacts found around edges when the coder cannot keep up with the detailed video content. Resemble speckles.

MPEG - Motion Picture Experts Group of ISO. Responsible for MPEG-1 and MPEG-2 standards.

MPEG-1 - Video Standard targeted at 1.5 Mbps playback on multimedia PCs.

MPEG-2 - Video Standard targeted at 2-10 Mbps broadcast television. Will also be used for higher bandwidth HDTV.

Multicast - Communication between a single sender and multiple receivers on a network. 

Multimode Fiber - Optical fiber that is designed to carry multiple light rays or modes concurrently, each at a slightly different reflection angle within the optical fiber core. 

Multiplexing - The combining of multiple data channels onto a single transmission medium. Any process through which a circuit normally dedicated to a single user can be shared by multiple users. Typically, user data streams are interleaved on a bit or byte basis (time division) or separated by different carrier frequencies ( frequency division).

Multipoint - A call involving three or more parties.

Multipoint circuit - A circuit consisting of three or more stations connected directly electrically.

MUX - An abbreviation for multiplexer, a device that sends multiple signals on a carrier channel at the same time in the form of a single, complex signal to another device that recovers the separate signals at the receiving end. 

Narrowband - Bandwidths from 64kbps to 2Mbps.

NIC - Network Interface Card. Connects a PC to a LAN.

N-ISDN - Narrowband ISDN (The ISDN currently used).

Network - A group of stations (computers, telephones, or other devices) connected by communications facilities for exchanging information. Connection can be permanent, via cable, or temporary, through telephone or other communications links. The transmission medium can be physical (i.e. fiber optic cable) or wireless (i.e. satellite).

Nodes - A point of interconnection to a network, such as computers, printers, routers, faxes, or bridges.

Noise - Caused by random electrical signals, which act to corrupt the bits being transmitted. Noise can come from outside electrical sources.

Non-ISDN line - Any connection from a CPE to a SPCS that is not served by D-Channel signaling.

Non-ISDN trunk - Any trunk not served by either SS7 or D-Channel signaling.

NT1 - Network Termination 1. Network termination equipment for ISDN BRI. A unit that provides physical and electromagnetic termination of the U-interface 2-wire transmission line, converts between Layer 1 formats used at the U- and T- reference points, and performs some maintenance functions. Turns a U interface into an S/T interface. Not needed when connecting to most digital PBXs.

NTSC - National Television Standards Committee. Standard for broadcast television in US and Japan. Theoretical resolution of 720X480, 30 interlaced frames per second.

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