AT&T MERLIN LEGEND Installation & Maintenance Manual page 39

System Description
There are different types of lines/trunks for the different functions
of each mode. A Key or Behind Switch system can use
loop-start (LS) lines
tie trunks
a DS1 facility programmed for either T1 or Integrated
Services Digital Network Primary Rate Interface (ISDN-PRI)
operation
a ground-start (GS) line only when registered under the MF
FCC classification
A Hybrid/PBX system can use
loop-start trunks
ground-start trunks
tie trunks
direct inward dialing (DID) trunks
a DS1 facility programmed for either T1 or ISDN-PRI
operation
The names of modules consist of a number identifying the
number of lines/trunks and/or stations that can be connected to
the module, followed by the types of lines and/or telephones it
supports. For example, the 408 GS/LS module provides four line
jacks and eight station jacks and supports ground-start or loop-
start lines.
The system supports 13 types of line/trunk and station modules
(see Figure 4). Table 1-1 lists the specifications for each type of
module.
See Appendix A for wiring diagrams.
1-8 Control Unit