Assigning Lines/Trunks To Data And Video Stations - AT&T MERLIN LEGEND Release 3.1 System Planning Manual

Assigning Lines/Trunks to Data and Video Stations

Assigning Lines/Trunks to Data and
Video Stations
The following types of outside lines/trunks are used to make and receive data
calls to and from data stations outside of the system:
Loop-Start (LS). This is the standard line/trunk for homes and small
businesses, and can be used to communicate with outside modem data
stations. Video calls are not made over loop-start lines/trunks. Loop-start
lines/trunks are the least expensive lines/trunks in some areas but have
the following disadvantages:
— They do not protect against glare, a condition that occurs when an
outside call is made at the same time that an incoming call arrives on
the same line/trunk.
— They may not provide reliable far-end disconnect for toll restriction.
!
Ground-Start (GS). This line/trunk is preferred for communication with
outside modem data stations. Ground-start lines/trunks provide improved
signaling and reliable far-end disconnect for secure toll restriction. Video
calls are not made over ground-start lines/trunks.
The following kinds of outside ground-start or loop-start lines/trunks can
be used for data communications:
— Basic lines/trunks
— Wide area telecommunications service (WATS)
— 800 service (inbound WATS)
— Foreign exchange (FX)
Ground-start/loop-start lines/trunks connect to ground-start/loop-start
jacks on the following types of modules in the control unit:
— 800 GS/LS
— 400 GS/LS/TTR
— 408 (LS lines/trunks only)
— 408 GS/LS
5–26
Data Communications
SECURITY ALERT:
Toll fraud can occur when loop-start lines/trunks are used with
unreliable disconnect. If the calling party stays on the line after the
called party hangs up, the central office will return a dial tone at the
conclusion of the call enabling the caller to place another call as if
it were being placed from your company.