Справочник Пользователя для Lucent Technologies 6.1

Issue 1

August 1998

Data Communications 

Page 5-27

Assigning Lines/Trunks to Data and Video Stations 

5

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.

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 returns 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.

■

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

— 400 (LS lines/trunks only)

— 800 (LS lines/trunks only)

— 408 GS/LS-MLX

— 800 GS/LS-ID