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Versions: 00 01 02 03 04 05 06 07 08 09 10 11 12 13 14 RFC 8119

Network Working Group                                          M. Mohali
Internet-Draft                                                    Orange
Updates: RFC4458 (if approved)                          January 21, 2015
Intended status: Informational
Expires: July 25, 2015


Session Initiation Protocol (SIP) Cause URI parameter for Service Number
                              translation
           draft-mohali-dispatch-cause-for-service-number-01

Abstract

   [RFC4458] defines a "cause" URI parameter as having predefined values
   for Redirecting reasons as a mapping from ITU-T Q.732.2-5 Redirecting
   Reasons.  The "cause" URI parameter is to be used in SIP or SIPs URI.
   In particular, it may appear in the History-Info header field
   defined in [RFC7044] that must be added in retargeted requests.
   This specification creates a new predefined value for cases when the
   retargeting is caused by a specific service action leading to a
   called service access number translation.
   This document updates [RFC4458].

Status of This Memo

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.

   Internet-Drafts are working documents of the Internet Engineering
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   Internet-Drafts are draft documents valid for a maximum of six months
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   time.  It is inappropriate to use Internet-Drafts as reference
   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on July 25, 2015.

Copyright Notice

   Copyright (c) 2015 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
   (http://trustee.ietf.org/license-info) in effect on the date of



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   publication of this document.  Please review these documents
   carefully, as they describe your rights and restrictions with respect
   to this document.

Table of Contents

   1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  2
   2.  Problem Statement  . . . . . . . . . . . . . . . . . . . . . .  3
   3.  Solution . . . . . . . . . . . . . . . . . . . . . . . . . . .  3
   4.  Example  . . . . . . . . . . . . . . . . . . . . . . . . . . .  5
   5.  IANA Considerations  . . . . . . . . . . . . . . . . . . . . .  6
   6.  Security Considerations  . . . . . . . . . . . . . . . . . . .  7
   7.  References . . . . . . . . . . . . . . . . . . . . . . . . . .  7
     7.1.  Normative References . . . . . . . . . . . . . . . . . . .  7
     7.2.  Informative References . . . . . . . . . . . . . . . . . .  7
   Author's Address . . . . . . . . . . . . . . . . . . . . . . . . .  8


1.  Introduction

   The History-Info header field [RFC7044] provides a mechanism to
   capture the history information associated with a Session Initiation
   Protocol (SIP) request.  This capability enables many enhanced
   services by providing the information as to how and why a SIP request
   arrives at a specific application or user.

   To be able to filter specific entries among the history information,
   tags have been defined in [RFC7044].  In particular, the "mp" and
   "rc" tags having the following definitions: The "mp" tag is added
   when the new target was determined based on a mapping to a user other
   than the target user associated with the Request-URI being
   retargeted. This allows identifying, retargeting that are result of a
   decision made by a particular type of application or that an initial
   request has been retargeted as a result of an application decision in
   a general manner. The "rc" tag is added when the new target
   represents a change in Request-URI, while the target user remains the
   same.

   Concurrently, a mechanism has been defined in [RFC4458] to add a
   "cause" URI parameter in the target URI to be able to identify
   retargeting due to the call forwarding supplementary services form
   other retargetings.  This "cause" URI parameter has defined values
   equivalent to the TDM Redirecting reasons. It is requested to pay
   attention not to get this "cause" URI parameter and the "cause"
   header parameter included in the Reason header field mixed up. The
   "cause" URI parameter may be used either in the History-info header
   field and/or in the Request-URI to indicate the service that the User
   Agent Server (UAS) receiving the message should perform.



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   In PSTN/ISDN there is another kind of retargeting introduced by the
   Intelligent Network (IN) services. Indeed, the [ITU-T_I.312/Q.1201]
   defined the IN term to describe an architectural concept which is
   intended to be applicable to all telecommunications networks. IN aims
   to ease the introduction of new services (i.e. Universal Personal
   Telecommunication (UPT), Virtual Private Network (VPN), Freephone,
   etc.) based on greater flexibility and new capabilities. For these IN
   services, it was introduced in ISUP the "called IN number" and the
   "original called IN number" parameters that enable to keep the
   information of the service access number requested prior its
   translation.

   This specification proposes a solution to allow the identification of
   well-known services such as premium or toll free services that are
   doing access number translation.

2.  Problem Statement

   A mechanism is required to identify URIs that are issued from a
   retargeting or number translation by a specific service similar to
   PSTN/ISDN IN services.

   This mechanism needs to cover at least the IN services that can be
   identified in the ISUP signaling in the "called IN number" and
   "original called IN number" optional parameters defined in
   [ITU-T_Q.763] and used in ISUP/INAP interworking as described in
   [ITU-T_Q.1600].

3.  Solution

   A new alternative value for the "cause" URI parameter of the 'sip:'
   or 'sips:' URI schemes is defined.
   This value may be used in a 'sip:' or 'sips:' URI inserted in the
   History-Info header field [RFC7044] when the "mp" or "rc" tag is
   present and the URI is issued from a retargeting or an access number
   translation by a specific service similar to PSTN/ISDN IN services
   that is not a call forwarding service.
   As defined in [RFC4458], the cause URI parameter must be encoded in
   the new target URI when generated by the service.


   The ABNF grammar [RFC5234] for the cause-param and target-param
   parameters is reminded below as it has been subject to Errata [ID:
   1409] in [RFC4458].  The Status-Code is defined in [RFC3261].

              target-param = "target=" pvalue

              cause-param = "cause=" Status-Code



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   The following value for this URI parameter is added to the existing
   ones:



                   +---------------------------------+-------+
                   | Service Type                    | Value |
                   +---------------------------------+-------+
                   | Service number translation      | 380   |
                   +---------------------------------+-------+









































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4.  Example

   In this section an example will be provided to illustrate the
   application of the new cause-param value.

   This example call flow shows a UAC that does not support
   History-Info.


            Alice      Toll-Free Service   Atlanta.com          John
             |                |              |                   |
             |    INVITE F1   |              |                   |
             |--------------->|   INVITE F2  |                   |
             |                |------------->|                   |
             |                |              |  INVITE F3        |
             |                |              |------------------>|

                          * Rest of flow not shown *

             Figure 1: Service Access Number Translation Example


      Message Details

      F1 INVITE 192.0.2.1 -> Toll-Free Service

      INVITE sip:+18005551002@example.com;user=phone  SIP/2.0
      Via: SIP/2.0/TCP 192.0.2.1:5060;branch=z9hG4bK74bf
      From: Alice <sip:+15551001@example.com;user=phone>;tag=9fxced76sl
      To: <sip:+18005551002@example.com;user=phone>
      Call-ID: c3x842276298220188511
      CSeq: 1 INVITE
      Max-Forwards: 70
      Contact: <sip:alice@192.0.2.1>
      Content-Type: application/sdp
      Content-Length: <appropriate value>

      [SDP Not Shown]


      F2 INVITE Toll-Free Service -> Atlanta.com

      INVITE sip:+15555551002@atlanta.com SIP/2.0
      Via: SIP/2.0/TCP 192.0.2.4:5060;branch=z9hG4bK-ik8
      Via: SIP/2.0/TCP 192.0.2.1:5060;branch=z9hG4bK74bf
      From: Alice <sip:+15551001@example.com;user=phone>;tag=9fxced76sl
      To: <sip:+18005551002@example.com;user=phone>
      Call-ID: c3x842276298220188511



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      CSeq: 1 INVITE
      Max-Forwards: 69
      Supported: histinfo
      History-Info: <sip:+18005551002@example.com;user=phone>;index=1
      History-Info: <sip:+15555551002@atlanta.com;cause=380>;
                    index=1.1;mp=1
      Contact: <sip:alice@192.0.2.1>
      Content-Type: application/sdp
      Content-Length: <appropriate value>

      [SDP Not Shown]


      F3 INVITE Atlanta.com -> John

      INVITE sip:john@198.51.100.2 SIP/2.0
      Via: SIP/2.0/TCP 198.51.100.1:5060;branch=z9hG4bKpxk7g
      Via: SIP/2.0/TCP 192.0.2.4:5060;branch=z9hG4bK-ik8
      Via: SIP/2.0/TCP 192.0.2.1:5060;branch=z9hG4bK74bf
      From: Alice <sip:+15551001@example.com;user=phone>;tag=9fxced76sl
      To: <sip:+18005551002@example.com;user=phone>
      Call-ID: c3x842276298220188511
      CSeq: 1 INVITE
      Max-Forwards: 68
      Supported: histinfo
      History-Info: <sip:+18005551002@example.com;user=phone>;index=1
      History-Info: <sip:+15555551002@atlanta.com;cause=380>;
                    index=1.1;mp=1
      History-Info: <sip:john@atlanta.com>;index=1.1.1;rc=1.1
      History-Info: <sip:john@198.51.100.2>;index=1.1.1.1;rc=1.1.1
      Contact: <sip:alice@192.0.2.1>
      Content-Type: application/sdp
      Content-Length: <appropriate value>

      [SDP Not Shown]


5.  IANA Considerations

   [RFC3969] defines a 'sip:' or 'sips:' URI Parameter sub registry.
   [RFC4458] defines a "cause" parameter specified as having predefined
   values.  This RFC defines a new value for the "cause" parameter: 380.
   This RFC has been added to the references listed for the "cause" the
   "SIP/SIPS URI Parameters" sub-registry in
   <http:/www.iana.org/assignments/sip-parameters> for the "cause"
   parameter.





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    Parameter Name         Predefined Values            References
    --------------         -----------------        ------------------
       cause                      Yes               [RFC4458][RFCxxxx]

6.  Security Considerations

   The security considerations in [RFC4458] apply.

   A privacy service that performs the "Privacy: header" Service
   [RFC3323] must remove the cause URI parameter from the URI.  Privacy
   of the parameters, when they form part of a URI within the History-
   Info header field, is covered in [RFC7044].

7.  References

7.1.  Normative References

   [RFC2119]  "Key words for use in RFCs to Indicate Requirement
              Levels", RFC 2119, March 1997.

   [RFC3261]  "SIP: Session Initiation Protocol", RFC 3261, June 2002.

   [RFC3323]  "A Privacy Mechanism for the Session Initiation Protocol
              (SIP)", RFC 3323, November 2002.

   [RFC3969]  "The Internet Assigned Number Authority (IANA) Uniform
              Resource Identifier (URI) Parameter Registry for the
              Session Initiation Protocol (SIP)", December 2004.

   [RFC7044]  "An Extension to the Session Initiation Protocol (SIP) for
              Request History Information", RFC 7044, February 2014.

7.2.  Informative References

   [ITU-T_I.312/Q.1201]
              ITU-T Recommendation I312/Q.1201, "Principles of
              Intelligent Network Architecture", October 1992.

   [ITU-T_Q.1600]
              ITU-T Recommendation Q.1600, "Signalling System No. 7 -
              Interaction between ISUP and INAP", September 1997.

   [ITU-T_Q.763]
              ITU-T Recommendation Q.763, "Signalling System No. 7 -
              ISDN User Part formats and codes.", December 1999.

   [RFC4458]  "Session Initiation Protocol (SIP) URIs for Applications
              such as Voicemail and Interactive Voice Response (IVR)",



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              RFC 4458, April 2006.

   [RFC5234]  "Augmented BNF for Syntax Specifications: ABNF", RFC 5234,
              January 2008.

Author's Address

   Marianne Mohali
   Orange
   38-40 rue du General Leclerc
   Issy-Les-Moulineaux Cedex 9  92794
   France

   Phone: +33 1 45 29 45 14
   Email: marianne.mohali@orange.com




































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