AT&T System 75, Wiring Diagram

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CHAPTER 6. GLOSSARY
Feature
Foreign Exchange (FX)
A specifically defined function or service provided by the switch.
A CO other than the one providing local access to the public
telephone network.
Foreign Exchange Trunk
A telecommunications channel that directly connects the switch to a
central office other than its local central office.
Ground-Start Trunk
On outgoing calls, the switch transmits a request for services to the
distant switching system by grounding the trunk ring lead. When the
distant system is ready to receive the digits of the called number,
that system grounds the trunk tip lead. When the switch detects this
ground, the digits are sent. (Tip and ring are common nomenclature
to differentiate between ground-start trunk leads.) On incoming
calls, detection of ground on the ring lead is sufficient to cause the
call to route to a predetermined destination, normally the system
attendant group. No digits are received.
Information Outlet
An 8-pin modular wall jack.
Interface
A common boundary between two systems or pieces of equipment.
Internal Call
A connection between two users within the switch.
Link
A transmitter-receiver channel or system that connects two locations.
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