AT&T System 25 - Manual (Page 422)

GLOSSARY
Ground-Start Trunk
On outgoing calls, System 25 transmits a request for service 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 System 25 detects this
ground, it removes the ground from the ring lead and the trunk is
ready for service.
Home Numbering Plan Area (HNPA) Code
The local area code. Does not have to be dialed to place calls to
numbers within the local numbering plan area.
Immediate-Start Tie Trunk
After establishing a connection with the distant switching system for
an outgoing call, the system waits a nominal 65 milliseconds before
sending the digits of the called number. This allows time for the
distant system to prepare to receive the digits. Similarly, on an
incoming call, the system has 65 milliseconds to prepare to receive
the digits.
I n t e r c e p t T o n e
On System 25, this tone is the same as Reorder Tone. Indicates a
dialing error or denial of the service requested.
I n t e r f a c e
Internal
A common boundary between two systems or pieces of equipment.
C a l l
A connection between two stations within the system. Sometimes
called an inside or intercom call.
l-Use Lamp
A red lamp on a multiline voice terminal that lights
appearance will be selected when the handset is
appearance is active when a user is off-hook. to show which call
lifted or which call
G-9