Network Working Group                                          M. Mohali
Internet-Draft                                                    Orange
Updates: RFC4458 (if approved)                          October 26, 2014
Intended status: Informational
Expires: April 29, 2015


Session Initiation Protocol (SIP) Cause URI parameter for Service Number
                              translation
           draft-mohali-dispatch-cause-for-service-number-00

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 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 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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   This Internet-Draft will expire on April 29, 2015.

Copyright Notice

   Copyright (c) 2014 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
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Table of Contents

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

1.  Introduction

   The History-Info header [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].  For instance, the "mp" tag
   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 "mp" tag is added when the target was determined based
   on a mapping to a user other than the target user associated with the
   Request-URI being retargeted.

   Additionally, a mechanism has been defined in [RFC4458] to add a
   "cause" parameter in the target URI to be able to identify
   retargeting due to the call forwarding supplementary services form
   other retargetings.  This "cause" parameter has defined values
   equivalent to the TDM Redirecting reasons.

   There is no solution to identify other reasons for retargeting than
   call forwarding service whereas some others already exist in PSTN/
   ISDN.  In particular, it is the case for IN services number
   translation identified in ISUP by the "called IN number" and the
   "original called IN number".

   Cause is a URI parameter that is used to indicate the service that
   the User Agent Server (UAS) receiving the message should perform.



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   This specification proposes a solution for well-known services such
   as premium or tool free services that are doing retagertings.

2.  Problem Statement

   A mechanism is required to identify URIs that are issued form a
   retargeting 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" 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 [RFC7044] when the "mp" tag is present and the
   URI is issued form a retargeting by a specific service similar to
   PSTN/ISDN IN services.
   As defined in [RFC4458], the cause URI parameter MUST be encoded in
   the 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


   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 hte new cause-param value.

   History-Info: <sip: ToolFree_service_number>;index=1,
   <sip: callcenter_addr;cause=380>;index=1.1;mp=1

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: 480.
   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.


    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.




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

7.2.  Informative References

   [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)",
              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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