AT&T MERLIN LEGEND Installation & Maintenance Manual page 707

Glossary
T
T1
A digital transmission carrier
path that in North America
transmits at the DS1 rate of
1.544 Mbps.
telephone power supply unit
Equipment that provides
power to an individual
telephone.
tie trunk
A private line directly
connecting two
communications systems.
time-division multiplexing
(TDM)
A process where the
transmission channel is
divided.
timer
A built-in timing device in a
display telephone.
time-slot interchanger
An element of a time-division
switching network that
separates and switches time-
division multiplexed (TDM)
signals.
tip/ring (T/R)
The contacts and associated
conductors of a single-line
telephone plug or jack.
GL-22 Glossary
touch-tone gate
An operation used to
determine if a call is from a
touch-tone or rotary
telephone.
touch-tone receiver (TTR)
A device used to decode
touch-tones dialed from
single-line telephones or
Remote Access telephones.
U
uninterruptible power supply
(UPS)
A device that connects to the
communications system to
provide 117 VAC to the
equipment when the
commercial power source
fails.
unit load
A measure of the power load
drain of a module, telephone,
or adjunct.