To connect the BRI ports:
1. Connect the BRI cable to the device's BRI RJ-45 port.
2. Connect the other end of the cable to your ISDN telephone or PBX/PSTN switch.
Figure 5-11: Cabling BRI Ports
5.4.2 Connecting PSTN Fallback for BRI Lines
The device supports PSTN Fallback for BRI lines. If the device loses power, for example, due
to a power outage or the unplugging of its power cable, it automatically routes calls from the
Tel side to the PSTN (instead of the IP network).
PSTN Fallback is supported if the device houses one or more BRI modules, where each BRI
module provides two or four spans.
In the event of a PSTN fallback, the BRI module's metallic relay switch automatically connects
line Port 1 (I) to Port 2 (II) of the BRI module.
For example, if a PBX trunk is connected to Port 1 and the PSTN network is connected to
Port 2, when PSTN Fallback is activated, calls from the PBX are routed directly to the PSTN
through Port 2.
Warning:
• BRI port cabling must be routed only indoors and must not exit the building.
• To protect against electrical shock and fire, use a 26 AWG min wire to connect the
BRI ports to the PSTN.
Cable specifications:
Cable: 26 AWG min.
Connector Type: RJ-45
Connector Pinouts:
Figure 5-12: RJ-45 Connector Pinouts for BRI PSTN Fallback
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