AT&T System 25 - Manual (Page 419)

GLOSSARY
Delay-Dial Tie Trunk
Digital
Digital
After a request for service (called a seizure) is detected on an
incoming trunk, the system sends a momentary signal followed by a
steady tone over the trunk. This informs the calling party that dialing
can start. This type of trunk allows dialing directly into the system;
that is, the digits are received as they are dialed.
Data Endpoints
In System 25, digital data endpoints include any DTE or DCE with an
RS-232C interface to the switch connected through Asynchronous
Data Units.
Tape Unit (DTU)
The RS-232C
translations. peripheral DTE used to store and reload system
Direct Extension Selector (DXS) Console
An option at the attendant console that allows an attendant direct
access to voice terminals by pressing a Group Select button and a
D X S b u t t o n .
Direct Group Call (DGC)
An incoming call that arrives on a loop-start, ground-start, or tie
trunk and is routed to a predetermined group of stations (for
example, sales department and service department).
Direct Inward Dialing (DID)
A service whereby the called extension (station) number is
transmitted to a PBX by the central office (CO) and incoming calls
are routed directly to the called station, bypassing the attendant.
D S n
Generally, Digital Signal (DS) level n refers to the logical organization
or division of the bandwith available on T carriers. DSO is a single
64 Kbps channel. Twenty-four DS0 channels combine to form a DS1
channel.
Four DS1 channels combine to form a DS2 channel.
Twenty-eight DS1 channels combine to form a DS3 channel.
G-6