Alternative Routing upon SIP 3xx with Multiple Contacts

You can configure how the device handles received SIP 3xx responses that contain multiple alternative contacts. The 3xx response indicates that the original destination is unavailable (e.g., 301 Moved Permanently – user cannot be found) and that the call can be redirected to alternative destinations specified in the SIP Contact headers.

Configured by the '3xx Use Alt Route Reasons' parameter, the device can handle the receipt of 3xx responses using one of the following methods:

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The device tries each contact sequentially, listed in the Contact headers, until a successful destination is found. If a contact responds with a SIP 486 or 600, the device does not try to redirect the call to the next contact and drops the call.

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The device tries each contact sequentially, listed in the Contact headers. If a SIP 6xx Global Failure response is received during this process (e.g., 600 Busy Everywhere), the device does not try to redirect the call to the next contact and drops the call.

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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), 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.

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To configure handling of SIP 3xx responses with multiple contacts:

1.

Open the Gateway Advanced Settings page (Setup menu > Signaling & Media tab > Gateway folder > Gateway Advanced Settings).

2.

From the '3xx Use Alt Route Reasons' drop-down list, select the required handling.

3.

Click Apply.