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 Task Force (IETF). Note that other groups may also distribute working documents as Internet-Drafts. The list of current Internet- Drafts is at http://datatracker.ietf.org/drafts/current/. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any 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 Mohali Expires July 25, 2015 [Page 1]
Internet-Draft Cause for service number translation January 21, 2015 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. Mohali Expires July 25, 2015 [Page 2]
Internet-Draft Cause for service number translation January 21, 2015 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 Mohali Expires July 25, 2015 [Page 3]
Internet-Draft Cause for service number translation January 21, 2015 The following value for this URI parameter is added to the existing ones: +---------------------------------+-------+ | Service Type | Value | +---------------------------------+-------+ | Service number translation | 380 | +---------------------------------+-------+ Mohali Expires July 25, 2015 [Page 4]
Internet-Draft Cause for service number translation January 21, 2015 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 Mohali Expires July 25, 2015 [Page 5]
Internet-Draft Cause for service number translation January 21, 2015 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. Mohali Expires July 25, 2015 [Page 6]
Internet-Draft Cause for service number translation January 21, 2015 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)", Mohali Expires July 25, 2015 [Page 7]
Internet-Draft Cause for service number translation January 21, 2015 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 Mohali Expires July 25, 2015 [Page 8]