Pstn Fallback - AudioCodes Mediant 3000 User Manual

User's Manual
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The device redirects the call to the first contact listed in the Contact header. If the
contact responds with a SIP response that is configured in the Reasons for Tel-to-IP
Alternative Routing table (see ''Alternative Routing Based on SIP Responses'' on page
514), the device tries to redirect the call to the next contact, and so on. If a contact
responds with a response that is not configured in the table, the device does not try to
redirect the call to the next contact and drops the call.
Note:
try to redirect the call to the next contact. Instead, the device continues with the
regular authentication process, as indicated by these response types.

25.6.4 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 steps for configuring alternative Tel-to-IP routing to the legacy PSTN are summarized
below.
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To configure alternative Tel-to-IP routing to the legacy PSTN:
1. Configure an alternative routing rule in the Tel-to-IP Routing table with the same call
matching characteristics (e.g., phone number destination), but where the destination is
the IP address of the device itself.
2. Configure an IP-to-Tel routing rule in the Inbound IP Routing table 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. For configuring IP-to-Tel routing rules, see ''Configuring IP to Trunk
Group Routing Rules'' on page 505.
Version 7.0
If a SIP 401 or 407 response is received from a contact, the device does not
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25. Routing
Mediant 3000