The Use of the SIPS URI Scheme in the Session Initiation Protocol (SIP)
RFC 5630

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Network Working Group                                           F. Audet
Request for Comments: 5630                                    Skype Labs
Updates: 3261, 3608                                         October 2009
Category: Standards Track

The Use of the SIPS URI Scheme in the Session Initiation Protocol (SIP)

Abstract

   This document provides clarifications and guidelines concerning the
   use of the SIPS URI scheme in the Session Initiation Protocol (SIP).
   It also makes normative changes to SIP.

Status of This Memo

   This document specifies an Internet standards track protocol for the
   Internet community, and requests discussion and suggestions for
   improvements.  Please refer to the current edition of the "Internet
   Official Protocol Standards" (STD 1) for the standardization state
   and status of this protocol.  Distribution of this memo is unlimited.

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   document authors.  All rights reserved.

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Audet                       Standards Track                     [Page 1]
RFC 5630                          SIPS                      October 2009

Table of Contents

   1. Introduction ....................................................3
   2. Terminology .....................................................3
   3. Background ......................................................3
      3.1. Models for Using TLS in SIP ................................3
           3.1.1. Server-Provided Certificate .........................3
           3.1.2. Mutual Authentication ...............................4
           3.1.3. Using TLS with SIP Instead of SIPS ..................4
           3.1.4. Usage of the transport=tls URI Parameter and
                  the TLS Via Parameter ...............................5
      3.2. Detection of Hop-by-Hop Security ...........................6
      3.3. The Problems with the Meaning of SIPS in RFC 3261 ..........7
   4. Overview of Operations ..........................................9
      4.1. Routing ...................................................11
   5. Normative Requirements .........................................13
      5.1. General User Agent Behavior ...............................13
           5.1.1. UAC Behavior .......................................13
                  5.1.1.1. Registration ..............................14
                  5.1.1.2. SIPS in a Dialog ..........................15
                  5.1.1.3. Derived Dialogs and Transactions ..........15
                  5.1.1.4. GRUU ......................................16
           5.1.2. UAS Behavior .......................................17
      5.2. Registrar Behavior ........................................18
           5.2.1. GRUU ...............................................18
      5.3. Proxy Behavior ............................................18
      5.4. Redirect Server Behavior ..................................20
   6. Call Flows .....................................................21
      6.1. Bob Registers His Contacts ................................22
      6.2. Alice Calls Bob's SIPS AOR ................................27
      6.3. Alice Calls Bob's SIP AOR Using TCP .......................36
      6.4. Alice Calls Bob's SIP AOR Using TLS .......................50
   7. Further Considerations .........................................51
   8. Security Considerations ........................................52
   9. IANA Considerations ............................................52
   10. Acknowledgments ...............................................52
   11. References ....................................................53