AT&T MERLIN LEGEND Release 2.0 Equipment And Operations Manual page 78

Hardware Components
When the system contains a 012 or 008 OPT module, a 129B Frequency
Generator (ring generator) must be installed in the power supply module of
each carrier that houses one or more of these modules.
A green light-emitting diode (LED) on the power supply remains on as long as
the module is receiving power. The power supply also has an on/off switch and
a modular telephone jack for connecting an auxiliary power unit as needed (see
Figure 2-3).
Figure 2-3. Power Supply
Line/Trunk and Station Modules
The line/trunk and station modules have jacks for connecting the telephone
company lines/trunks and the station wires to the control unit. The station wiring
connects to individual telephones and to adjuncts such as answering machines
and fax machines.
A system with a basic carrier has five slots for modules. Up to two expansion
carriers can be added, each one adding six slots for line/trunk or station
modules.
2-4 Control Unit