Administrator's Guide

U
Issue 5 October 2002 1999555-233-506
tone ringer
A device with a speaker, used in electronic voice terminals to alert the user.
TOP
Task-oriented protocol
trunk
A dedicated telecommunications channel between two communications systems or COs.
trunk allocation
The manner in which trunks are selected to form wideband channels.
trunk-data module
A device that connects off-premises private-line trunk facilities and DEFINITY ECS. The trunk-data module
converts between the RS-232C and the DCP, and can connect to DDD modems as the DCP member of a
modem pool.
trunk group
Telecommunications channels assigned as a group for certain functions that can be used interchangeably
between two communications systems or COs.
TSA
Terminal Self-Administration
TSAPI
Telephony Services Application Programming Interface
TSC
Technical Service Center
TTI
Terminal translation initialization
TTR
Touch-tone receiver
TTT
Terminating trunk transmission
TTTN
See tandem tie-trunk network (TTTN).
TTY
Teletypewriter
U
UAP
Usage-allocation plan
UART
Universal asynchronous transmitter
UCD
Uniform call distribution