Zhone Technologies 600 - Manual (Page 116)

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