Redirect Server

The entity that receives a request and sends back a reply containing a list of the current location of a particular user is called redirect server. A redirect server receives requests and looks up the intended recipient of the request in the location database created by a registrar. It then creates a list of current locations of the user and sends it to the request originator in a response within 3xx class.

The originator of the request then extracts the list of destinations and sends another request directly to them. The following picture shows a typical redirection.

SIP redirect diagram