AT&T System 75 Wiring Diagram page 334

Loop-Start Trunk
After establishing a connection with the distant switching system for
an outgoing call, the switch waits for a signal on the loop formed by
the trunk leads before sending the digits of the called number. On
incoming calls, the received request for service is sufficient to cause
the call to route to a predetermined destination, normally the system
attendant group. No digits are received.
Main/Satellite/Tributary
A Main switch provides the following: interconnection, by tie trunks,
with one or more subtending switches, called satellites; all attendant
positions for the main/satellite configuration; and, access to and
from the public network. To a user outside the complex, a
main/satellite configuration appears as a single switch, with a single
listed directory number. A tributary is a switch, connected to the
main by tie trunks, which has its own attendant position(s) and its
own listed directory number.
Modular Processor Data Module
See Processor Data Module.
Modular Trunk Data Module
See Trunk Data Module.
Modem Pooling
Provides shared-use conversion resources to eliminate the need for
a dedicated modem when a data module accesses, or is accessed
by, an analog line or trunk.
Multiplexer
A device for simultaneous transmission of two or more signals over
a common transmission medium.
Network
An arrangement of inter- and/or intra-location circuits designed to
perform a specific function.
CHAPTER 6. GLOSSARY
6-5