Internet DRAFT - draft-mohali-cause-for-services
draft-mohali-cause-for-services
Network Working Group M. Mohali
Internet-Draft Orange
Updates: RFC4458 (if approved) October 13, 2014
Intended status: Informational
Expires: April 16, 2015
Session Initiation Protocol (SIP) Cause URI parameter for Service Number
translation
draft-mohali-cause-for-services-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.
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This Internet-Draft will expire on April 16, 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
to this document.
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 values for this URI parameter are added to the existing
ones:
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==========================================================
| Service Name | Value |
| | |
==========================================================
|IN service number (default and generic | |
|value for mapping of the Called IN number| 380 |
|and the original called IN number) | |
|or service access number translation | |
==========================================================
4. Example
In this section an example will be provided to illustrate the
application of hte new cause-param value.
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.
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[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_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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