Zhone Technologies 600 User Manual

Page of 240
5-6 
Server Cards
Model No.
Running Head
Introduction
ISDN-PRI Card
Figure 5-4 shows how the application in Figure 5-3 would be set up if the user’s PBX was not 
connected to the system.
The disadvantage of this configuration is that the PBX may not be able to support two D 
channels, may not be able to handle the differences in D channel protocols between the two 
carriers, and may not be able to route calls to the appropriate carrier.
Figure 5-4. ISDN-PRI Links to Two Carriers
Carrier A
ISDN Switch
Carrier B
ISDN Switch
User Side
User Side
Network Side
Network Side
23B+D
23B+D
ISDN PBX