Instruction manual

Features
Differences Between Full Centrex and Limited Centrex
The major difference between Full Centrex and Limited Centrex is where and
how PBX functions are provided:
■ In Full Centrex, the Centrex Service provides PBX services to all
telephones
■ In Limited Centrex, the Centrex Service provides PBX services to
telephones making calls at the Centrex level on Prime Lines, while other
services are provided by the communications system acting as a switch
for calls between extensions and calls that do not require Centrex
features
In Full Centrex Service:
■ The communications system operates in Behind Switch mode
■ Calls can be made between Centrex extensions at separate sites served
by the same Centrex
■ Key mode features are provided by the communications system
■ Intercom calls can be made between communications system extensions
■ A switchhook flash, feature access code, or feature button is interpreted
as intended for the Centrex Service
In Limited Centrex Service:
■ The communications system operates in Key or Hybrid/PBX mode
■ Intercom calls can be made between communications system extensions
■ Calls to Centrex extensions require access to a Prime Line
■ A switchhook flash, feature access code, or feature button is interpreted
as intended for the communications system
■ Outside calls using Centrex Service are made through individual Prime
Lines or pooled Prime Lines
■ Other types of lines (TIE, DID, T1) can also be used for outside calls
without using Centrex Service
Considerations and Constraints
To prevent user confusion, extension numbers in the communications system
should reflect the ending digits of the Centrex station line number. For example,
a telephone with a Centrex Prime Line number of 4322 should have an
extension number of 4322 in a 4-digit numbering plan, 322 in a 3-digit
numbering plan, or 22 in a 2-digit numbering plan.
Centrex Operation 87