SIP REDIRECT _voip technical data

SIP Redirect

The SIP Redirect feature allows the IMG to respond to the 3xx class of SIP messages returned from a Redirect server. The 3XX responses provide information about a user ' s new location, or alternative services that is able to satisfy the Call. This feature was based on RFCs 3261 section 8.1.3.4 and RFC 2543.

In a SIP network it are very common to have a re-direct server which determines where to route the call. The redirect server may reply to the 2020 IMG with a-response which has a list of contacts to try-connect with. The 2020 IMG would try each one of the those contacts one in a time, until the call are completed, to a maximum of attempts. The 2020 IMG accepts a redirect to another endpoint in the SIP network and the SIP endpoint does not have to be one O f the configured as an external gateway within WebUI.

The SIP Redirect feature is enabled by default but can to disabled through the 3XX Redirect Support field in the SIP Profi Le WebUI Page.

Call flow

Supported 3xx Redirect Responses

3XX responses give information about the user ' s new location or alternative services that might is able to satisfy the CAL L.

Multiple choices-the address at the request resolved to several choices, and the, and the own specific, and th e User (or UA) can select a preferred communication end point and redirect it request to that location.

The moved permanently-the user can no longer is found at the address in the Request-uri, and the requesting client Shoul  D retry at the "new address" given by the Contact Header field (section 20.10). The requester SHOULD update any local directories, address books, and user location caches with this new value and Redirec T future requests to the "address" (es) listed.

302 moved temporarily-the requesting client SHOULD retry the request at the "new Address" (es), given by the contact header  Field (Section 20.10. The Request-uri of the new Request uses the Contact header field in the response.

305 Use Proxy-305 provides information for next hop to reach Proxy server. The requested resource must is accessed through the proxy given by the contact field.  The Contact field gives the URI of the proxy.  The recipient is expected to repeat this single request via the proxy. 305 (use Proxy) responses must is generated by UASs.

3xx Response Mapping

If the SIP Redirect Feature has been disabled, the 2020 IMG would map the 3xx responses to 4xx responses as shown below:

Redirection (3xx) Response

Maps to 4xx (client error) response

Multiple choices

410 Gone

Permanently moved

410 Gone

302 Moved temporarily

Unavailable temporarily

305 Use Proxy

410 Gone

380 Alternative Service

410 Gone

Any other 3xx response

410 Gone