Abstract The procedures for handling SIP re-INVITEs are described in RFC 3261. Implementation and deployment experience has uncovered a number of issues with the original documentation@ and this document provides additional procedures that update the original specification to address those issues. In particular@ this document defines in which situations a UAS (User Agent Server) should generate a success response and in which situations a UAS should generate an error response to a re-INVITE. Additionally@ this document defines further details of procedures related to target-refresh requests.