
Changing Settings to Support PBX or Centrex Services
2-11
locations, keep the same extension numbers, and retain the phones’ programmed 
settings. 
Changing Settings to Support 
PBX or Centrex Services 
This section applies only if you use PBX or Centrex services with your system. If it 
does not apply, go to the next section, “System Programming Options.” 
■PBX services are provided by a private telephone switch. 
■Centrex services are provided by your local telephone company from a 
Central Office (CO) outside your premises. These services include the 
Centrex lines connected to your control unit modules and some set  of 
features—such as hold, conference, or transfer—that are available on 
those lines. Centrex services may be offered in your area under a different 
name. For specific Centrex features to be available to you, your company  
must subscribe to those features. For specific information about using 
Centrex, see the Centrex documentation provided by your local telephone 
company. 
Some of the issues you should consider when setting up your system to w ork 
effectively behind a PBX or Centrex system are discussed below. Chapter 5 
explains how to use the programming procedures discussed here. 
Recall Setting 
To set up your equipment to work properly with a PBX or Centrex system, first set 
Recall Timer Duration (#107) to match the setting used by your PBX or Centrex 
system (usually 800 msec, or “32”). This setting affects the length of a Recal l 
signal sent by the control unit to access PBX or Centrex servic es. 
Dialing Restrictions 
Outgoing Call Restriction (#401) is an equipment restriction intended to limit an 
extension’s dialing to “inside calls only” (using the i buttons on system 
phones) or to “inside and local calls only” (allowing calls within the PBX or Centrex 
system and local calls outside the PBX or Centrex system). Ho wever, if users in 
your system use a dial-out code (9 on most PBX or Centrex systems) before 
dialing numbers outside the PBX or Centrex system, the equipment will not be  
able to prevent toll calls for extensions restricted to “inside and local cal ls only” 
[unless you use Disallowed Phone Number Lists (#404) to prevent dialing to 
specific classes of numbers]. 
If your PBX or Centrex system includes dialing restrictions, use th ose instead of 
the equipment restrictions. If you have PBX or Centrex dialing restrictions on a line 
and also program equipment restrictions, both the PBX or Centrex system and