AudioCodes Mediant 1000B - Connecting the PSTN Fallback for BRI Lines; Figure 5-15: Cabling (Ports 1 and 2) PSTN Fallback

Hardware Installation Manual 5. Cabling the Device
Media Gateways & SBCs 53 Mediant 1000B Gateway & E-SBC
5.4.2 Connecting the 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). This guarantees call continuity.
PSTN Fallback is supported only on BRI modules that provide 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), and / or line Port 3 (III) to Port 4 (IIII) of the same 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.
 To connect the BRI line interfaces for 1+1 PSTN Fallback:
1. Connect line 1 to a PBX.
2. On the same BRI module, connect line 2 to the PSTN.
Figure 5-15: Cabling (Ports 1 and 2) PSTN Fallback
Notes:
• PSTN Fallback is supported only between ports on the same BRI module.
• This PSTN Fallback feature has no relation to the PSTN Fallback Software Upgrade
Key.