AudioCodes Mediant 1000B - Connecting the PSTN Fallback for E1;T1 Trunks; Figure 5-17: Cabling (Ports 1 and 2) PSTN Fallback

Hardware Installation Manual 5. Cabling the Device
Media Gateways & SBCs 55 Mediant 1000B Gateway & E-SBC
5.5.2 Connecting the PSTN Fallback for E1/T1 Trunks
The device supports PSTN Fallback for E1/T1 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 on E1/T1 ("TRUNKS") modules that provide two or four spans.
In the event of a PSTN fallback, the module's metallic relay switch automatically connects
trunk Port 1 (I) to Port 2 (II), and / or trunk Port 3 (III) to Port 4 (IIII) of the same 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 digital trunk interfaces for 1+1 PSTN Fallback:
1. Connect Trunk 1 to a PBX.
2. On the same TRUNKS module, connect Trunk 2 to the PSTN.
Figure 5-17: Cabling (Ports 1 and 2) PSTN Fallback
Notes:
• PSTN Fallback is supported only between ports on the same TRUNKS module.
• This PSTN Fallback feature has no relation to the PSTN Fallback Software Upgrade
Key.