SIP Interface to VoiceXML Media Services
RFC 5552

• Status
• IESG evaluation record
• IESG writeups
• Email expansions
• History

• Versions
• 04

Network Working Group                                           D. Burke
Request for Comments: 5552                                        Google
Category: Standards Track                                       M. Scott
                                                                 Genesys
                                                                May 2009

                SIP Interface to VoiceXML Media Services

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.

Copyright Notice

   Copyright (c) 2009 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents in effect on the date of
   publication of this document (http://trustee.ietf.org/license-info).
   Please review these documents carefully, as they describe your rights
   and restrictions with respect to this document.

Abstract

   This document describes a SIP interface to VoiceXML media services.
   Commonly, Application Servers controlling Media Servers use this
   protocol for pure VoiceXML processing capabilities.  This protocol is
   an adjunct to the full MEDIACTRL protocol and packages mechanism.

Burke & Scott               Standards Track                     [Page 1]
RFC 5552        SIP Interface to VoiceXML Media Services        May 2009

Table of Contents

   1. Introduction ....................................................3
      1.1. Use Cases ..................................................3
           1.1.1. IVR Services with Application Servers ...............3
           1.1.2. PSTN IVR Service Node ...............................4
           1.1.3. 3GPP IMS Media Resource Function (MRF) ..............5
           1.1.4. CCXML <-> VoiceXML Interaction ......................6
           1.1.5. Other Use Cases .....................................6
      1.2. Terminology ................................................7
   2. VoiceXML Session Establishment and Termination ..................7
      2.1. Service Identification .....................................7
      2.2. Initiating a VoiceXML Session .............................10
      2.3. Preparing a VoiceXML Session ..............................11
      2.4. Session Variable Mappings .................................12
      2.5. Terminating a VoiceXML Session ............................15
      2.6. Examples ..................................................16
           2.6.1. Basic Session Establishment ........................16
           2.6.2. VoiceXML Session Preparation .......................17
           2.6.3. MRCP Establishment .................................18
   3. Media Support ..................................................19
      3.1. Offer/Answer ..............................................19
      3.2. Early Media ...............................................19
      3.3. Modifying the Media Session ...............................21
      3.4. Audio and Video Codecs ....................................21
      3.5. DTMF ......................................................22
   4. Returning Data to the Application Server .......................22
      4.1. HTTP Mechanism ............................................22
      4.2. SIP Mechanism .............................................23
   5. Outbound Calling ...............................................25
   6. Call Transfer ..................................................25
      6.1. Blind .....................................................26
      6.2. Bridge ....................................................27
      6.3. Consultation ..............................................29
   7. Contributors ...................................................31
   8. Acknowledgements ...............................................31
   9. Security Considerations ........................................31
   10. IANA Considerations ...........................................32
   11. References ....................................................32
      11.1. Normative References .....................................32
      11.2. Informative References ...................................35
   Appendix A.  Notes on Normative References ........................36

Burke & Scott               Standards Track                     [Page 2]
RFC 5552        SIP Interface to VoiceXML Media Services        May 2009

1.  Introduction

   VoiceXML [VXML20], [VXML21] is a World Wide Web Consortium (W3C)
   standard for creating audio and video dialogs that feature
   synthesized speech, digitized audio, recognition of spoken and dual