IMG 1010 - SIP Redirect Server Support

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

In a SIP network it is very common to have a re-direct server which determines where to route the call.  The redirect server may reply to the IMG with a 300 response with a list of contacts to try. The IMG will try each one of those contacts one at a time, until the call is completed, to a maximum of 10 attempts. The IMG will only accept redirects to another endpoint in the SIP network. The endpoint does not have to be one of the configured SIP external gateways.

This feature is enabled by default in the SIP Profile (see IMG 1010 - SIP Profile - 10.5.3).

• The maximum number of redirects is 10.

• The same IP Profile is used for all attempts.

• Once a contact has responded with a 180 Ringing or 183, the IMG will not make any more redirect attempts

Not Supported

• Simultaneous redirects

• Redirection to another Channel Group

• 3xx Responses for Registration Requests

• 380 Responses (they will be mapped to 410 Gone error code and released)

• 305 Response (they will be mapped to 410 Gone error code and released)

• Location changes are not saved internally

• The IMG cannot be redirected back to the PSTN
   

3XX Response Mapping

If this feature is not enabled, the IMG will map the 3xx responses to 4xx responses, as shown below:

Example Call Flow

Open

Related topics

IMG 1010 - Supported 3xx Redirect Responses

IMG 1010 - SIP Profile - 10.5.3