Glossary Terms - "M"

MDF (Main Distribution Frame)
In telephony, a structure where telephone-subscriber lines are terminated. In conjunction with a PBX, the place where central-office telephone lines are connected to on-premises extensions.

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.

Media/Medium
The path along which a signal is propagated, such as wire pair, coaxial cable, optical fiber, or radio wave path.

Megabyte
1,048,576 bytes (written Mb.)

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.

MFJ. Modification of Final Judgment
The 1982 consent decree which, as of 1/1/84, broke up the Bell System into AT&T and the seven RBOCs. Also known as "divestiture;" technically a "modification" of the consent decree entered against Western Electric and AT&T in 1956.

Modem
Short for modulator-demodulator. Modems convert digital signals -- the binary computer language of zeros and ones -- into analog signals - the transmission method of telephones -- thereby enabling computers to send data over the telephone networks.

Monthly Recurring Charge (MRC)
The charges that a customer is required to pay on a month – to – month basis. These charges remain fixed and therefor can be budged. The charges usually relate to local services such as line fee, call features, pass through surcharges.

Multimedia
The combination of various forms of media (text, graphics, animation, audio, etc.) to communicate information. The term also refers to information products that include text, audio, and visual content.

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.

Multipoint
A configuration or topology, designed to transmit data between a central site and a number of remote terminals on the same circuit. Individual terminals will generally be able to transmit to the central site but not to each other.

Mbps 1.544
The speed of a T1 circuit.

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