PSTN Fallback

The PSTN Fallback feature enables the device to re-route a Tel-to-IP call to the legacy PSTN using one of its trunks if the IP destination is unavailable. For example, if poor voice quality is detected over the IP network, the device attempts to re-route the call to the PSTN.

The following procedure describes how to configure alternative Tel-to-IP routing to the PSTN.

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To configure alternative Tel-to-IP routing to the PSTN:

1.

In the Tel-to-IP Routing table (see Configuring Tel-to-IP Routing Rules), configure an alternative routing rule with the same call matching characteristics (e.g., phone number destination) as the "main" routing rule, but where the destination is the IP address of the device itself.

2.

In the IP-to-Tel Routing table (see Configuring IP-to-Tel Routing Rules), configure an IP-to-Tel routing rule to route calls received from the device (i.e., its IP address) to a specific Trunk Group connected to the PSTN. This configuration is necessary as the re-routed call is now considered an IP-to-Tel call.