Chapter 22 VoIP Solutions: SIP : FortiGate VoIP solutions: SIP : SIP messages and media protocols : SIP response messages : Redirection
  
Redirection
Redirection responses indicate that more information is required for the endpoint to respond to a request message. Redirection responses can contain the following reason codes and reason phrases:
300 Multiple choices
301 Moved permanently
302 Moved temporarily
305 Use proxy
380 Alternative service