GLOSSARY GL-17
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MPDM See modular processor data module.
MTDM See modular trunk data module.
mu-255 A type of code by which analog signals are encoded to digital signals.
multiplexer A device used to combine a number of individual channels into a common
bit stream for transmission.
multiplexing A process whereby a transmission facility is divided into two or more
channels, either by splitting the frequency band into a number of narrower
bands or by dividing the transmission channel into successive time slots.
See also time-division multiplexing.
nailed-up connection Obsolete. See dedicated switched connection and permanent switched
connection.
NCTE See network channel-terminating equipment.
network A series of points, nodes, or stations connected by communications
channels.
network-access unit
(NAU)
A circuit card that plugs into a PC’s expansion slot to connect that PC with
others to form a StarLAN network. See also StarLAN.
network channel-
terminating equipment
(NCTE)
Equipment used at a customer’s premises to provide facility terminations
and signaling compatibility. Also called channel service unit and
customer service unit. See also data service unit.
node A switching or control point for a network. Nodes are either tandem —
they receive signals and pass them on — or terminal — they originate or
terminate a transmission path.
nonfacility-associated
signaling (NFAS)
A method that allows multiple PRI links to share a single D-channel on
one of the spans. One T1 link is therefore configured as 23 B-channels
plus 1 D-channel, while the other spans that share the D-channel are
configured with 24 B-channels each. See also facility-associated
signaling and primary rate interface.
off premises Telephones or data terminals that are not located within the same building
or campus as a communications system or have loop lengths greater than
3500 feet.
off-hook A condition in which the handset of a telephone is off the switchhook or
the telephone is activated by other means, such as through a speakerphone
button.