AT&T System 85 - Manual (Page 134)

CHAPTER 9. GLOSSARY
Central Office (CO) Trunk
A telecommunications channel on the public network between the CO and the switch.
Channel
A communications path over which voice or data signals are carried.
Class of Service (COS)
A number that specifies the features and calling privileges that together determine the calling
privileges of a group of extension numbers.
Code Restriction Level (CRL)
A number that specifies the geographical areas or specific telephone numbers in those areas
that a user can access.
Confirmation Tone
Three short bursts of tone—indicate that a feature has been activated or cancelled.
Console
An electronic switchboard, with pushbutton control, used by the attendant to manage calls.
Console Referral Call
A call that is automatically directed to the attendant console when the Automatic Circuit
Assurance (ACA) feature is activated.
Default Voice Terminal
A preassigned telephone/voice terminal to which calls can be routed when the attendant
console is unattended.
Dial Tone
A continuous steady tone— indicates that dialing may begin or a feature may be activated.
9-3