AT&T MERLIN LEGEND Release 4.0 Feature Reference page 120

Feature Reference
Centrex Service Centrex Service
• 4-digit Centrex calls • 4-digit Centrex calls
• Use of Centrex Features • Use of Centrex Features
MERLIN LEGEND
Communication Systems
• 2, 3, or 4-digit intercom
• key mode features
Figure 4. Full Centrex Service
Limited Centrex
With limited Centrex service, users depend principally on the communications
system's features, but a limited number of prime lines can be used to access
the CO Centrex. There are two cases that are particularly suitable for limited
Centrex:
Centrex lines/trunks may be less expensive than other lines.
Different users may have different needs for telephone service, so that
some users benefit more from Centrex, while other users benefit more
from direct use of the communications system.
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Centrex Operation
Central Office Central Office
(External Calls) (External Calls)