Instruction manual

Features
To use the features available through Centrex, the user dials a Centrex feature
code from a touch-tone telephone. Some features must be programmed
especially for the customer by the telephone company at the central office (CO).
The system can be configured for either Full or Limited Centrex service.
Full Centrex
Full Centrex requires that each telephone have a direct Centrex line (Prime Line)
to the CO. Full Centrex can also be used when only some telephones have
Prime Lines, but the telephones without Prime Lines have limited ability to use
Centrex features. Prime Lines can be shared between telephones.
The Prime Line allows users to dial outside numbers directly after dialing an
access code (usually 9). For this reason, any calling restrictions for the
telephone must be administered by the telephone company at the CO.
The Prime Line is also used to call other four-digit Centrex extension numbers
that may be located at different sites served by the same telephone company.
The communications system’s intercom lines are used to dial other telephones
in the communications system,
With Full Centrex, users can send a switchhook flash via the Recall button. The
fixed function buttons (Hold, Drop, and Transfer) control Centrex features
rather than communication system features. (Additional buttons can be
programmed for communications system use.) The communications system will
not intercept or respond to recall or fixed function button signals. See
Recall/Timed Flash for additional information.
For Full Centrex operation, the communications system must be programmed
for Behind Switch mode. A Full Centrex configuration operates on three levels
as shown in Figure 3. The telephone user must be aware of which level they are
at when making a call or activating a telephone feature.
84 Centrex Operation