ECRIT Working Group M. Patel Internet-Draft Nortel Intended status: Standards Track December 16, 2008 Expires: June 19, 2009 SOS Uniform Resource Identifier (URI) Parameter for Marking of Session Initiation Protocol (SIP) Requests related to Emergency Services draft-patel-ecrit-sos-parameter-02.txt Status of this Memo By submitting this Internet-Draft, each author represents that any applicable patent or other IPR claims of which he or she is aware have been or will be disclosed, and any of which he or she becomes aware will be disclosed, in accordance with Section 6 of BCP 79. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF), its areas, and its working groups. Note that other groups may also distribute working documents as Internet- Drafts. 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." The list of current Internet-Drafts can be accessed at http://www.ietf.org/ietf/1id-abstracts.txt. The list of Internet-Draft Shadow Directories can be accessed at http://www.ietf.org/shadow.html. This Internet-Draft will expire on June 19, 2009. Abstract This document defines a new Session Initiation Protocol (SIP) Uniform Resource Identifier (URI) parameter intended for marking SIP registration requests related to emergency services. The usage of this new URI parameter complements the usage of the Service Uniform Resource Name (URN) and is not intended to replace it. Patel Expires June 19, 2009 [Page 1]
Internet-Draft SOS URI Parameter for SIP Emergency December 2008 Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . . 3 3. The "sos" URI Parameter . . . . . . . . . . . . . . . . . . . . 3 3.1. REGISTER Request . . . . . . . . . . . . . . . . . . . . . 4 3.2. 2xx Reponse to REGISTER Request . . . . . . . . . . . . . . 4 4. Formal Syntax . . . . . . . . . . . . . . . . . . . . . . . . . 4 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 4 6. Security Considerations . . . . . . . . . . . . . . . . . . . . 5 7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 5 8. References . . . . . . . . . . . . . . . . . . . . . . . . . . 5 8.1. Normative References . . . . . . . . . . . . . . . . . . . 5 8.2. Informative References . . . . . . . . . . . . . . . . . . 6 Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 6 Intellectual Property and Copyright Statements . . . . . . . . . . 7 Patel Expires June 19, 2009 [Page 2]
Internet-Draft SOS URI Parameter for SIP Emergency December 2008 1. Introduction One way to differentiate a SIP-based emergency call from an ordinary call is by the presence of the Service URN as defined in RFC 5031 [RFC5031] (and used in the IETF emergency services architecture described in PhoneBCP[I-D.ietf-ecrit-phonebcp]). The 3GPP IP Multimedia Subsystem (IMS) emergency services architecture, illustrated in 3GPP TS 23.167 [3GPP.23.167], specifies that the User Equipment (UE) performs emergency registration prior to or during the initiation of an emergency call. The circumstances where such an emergency registration is required are listed below: - the UE is not registered with its home network - is currently registered but roaming Emergency registration is possible only when the UE has sufficient credentials to register with its home network and can detect that an emergency session is initiated. Unfortunately, marking of the emergency registration can not be fulfilled by the use of the Service URN. When a UE issues an emergency marked REGISTER request it informs the registrar that the contact address and the address-of-record being registered is to be used for emergency calls, and roaming and barring restrictions should not be applied for the registered address-of- record. A call back from a PSAP would be routed to the registered contact address. This document proposes a way to mark a REGISTER message as an emergency registration. 2. Terminology The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in BCP 14, RFC 2119 [RFC2119] 3. The "sos" URI Parameter This section provides an overview of the proposed new URI parameter to be used for marking REGISTER requests related to emergency services. A new URI parameter "sos" is defined in this document. The "sos" Patel Expires June 19, 2009 [Page 3]
Internet-Draft SOS URI Parameter for SIP Emergency December 2008 parameter is appended to a URI consistent with RFC 3261 [RFC3261]. It is proposed that use of this URI parameter is restricted to the Contact header included in the REGISTER request (and the 2xx response to the REGISTER request) related to an emergency call only. The "sos" URI parameter MUST NOT be considered as a replacement for the Service URN for emergency calls originated by a UA. 3.1. REGISTER Request When the UA sends a REGISTER request for emergency registration, the "sos" URI parameter MUST be appended to the URI in the Contact header. This serves as an indication to the registrar that the request is for emergency registration. Example: Contact: "Alice" <sip:alice@example.com;sos> ;q=0.7; expires=3600 3.2. 2xx Reponse to REGISTER Request The "sos" URI parameter MUST be present in the Contact header in the 200 (OK) response sent by the registrar upon successful registration. The "sos" URI parameter is appended to the URI included in the Contact header, thus indicating to the UA that this contact address will be included in the Contact header of an INVITE for emergency call intiation. 4. Formal Syntax The following syntax specification uses the augmented Backus-Naur Form (BNF) as described in RFC 2234 [RFC2234] uri-parameter = *(";"value) value = sos 5. IANA Considerations This specification defines one new SIP URI parameter, as per the registry created by RFC 3969 [RFC3969] Parameter Name: sos Predefined Values: none Reference: [RFCXXXX] Patel Expires June 19, 2009 [Page 4]
Internet-Draft SOS URI Parameter for SIP Emergency December 2008 [NOTE TO IANA: Please replace XXXX with the RFC number of this specification.] 6. Security Considerations As an identifier, the "sos" parameter itself does not raise any particular security issues. The semantic described by the "sos" parameter are meant to be well-known so privacy considerations do not apply to the URN. The main possibility of attack involves use of the "sos" parameter to bypass the normal procedures in order to achieve fraudulent use of services or to bypass security procedures. The usage of this parameter as described in this document is purely for the purpose of the REGISTER message and hence in presence of user authentication it is ensured that the respective user can be held accountable. It is RECOMMENDED to log events of misuse of the "sos" URI parameter, for example by including it in a request or response not related to an emergency calls. 7. Acknowledgements The author would like to thank Keith Drage, Milo Orsic, John-Luc Bakker, Andrew Allen, Hiroshi Ishikawa, Sean Schneyer, Peter Leis, Georg Mayer, Marvin Bienn, Ricky Kaura, Steve Norreys, Laura Liess, AC Mahendran, Roozbeh Atarius, Ramachandran Subramanian and Sandeep Sharma for the discussions and contributions that lead to this work. 8. References 8.1. Normative References [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. [RFC3261] Rosenberg, J., Schulzrinne, H., Camarillo, G., Johnston, A., Peterson, J., Sparks, R., Handley, M., and E. Schooler, "SIP: Session Initiation Protocol", RFC 3261, June 2002. [RFC2234] Crocker, D., Ed. and P. Overell, "Augmented BNF for Syntax Specifications: ABNF", RFC 2234, November 1997. [RFC3969] Camarillo, G., "The Internet Assigned Number Authority (IANA) Uniform Resource Identifier (URI) Parameter Patel Expires June 19, 2009 [Page 5]
Internet-Draft SOS URI Parameter for SIP Emergency December 2008 Registry for the Session Initiation Protocol (SIP)", BCP 99, RFC 3969, December 2004. 8.2. Informative References [I-D.ietf-ecrit-phonebcp] Rosen, B. and J. Polk, "Best Current Practice for Communications Services in support of Emergency Calling", draft-ietf-ecrit-phonebcp-06 (work in progress), November 2008. [RFC5031] Schulzrinne, H., "A Uniform Resource Name (URN) for Emergency and Other Well-Known Services", RFC 5031, January 2008. [3GPP.23.167] 3GPP, "IP Multimedia Subsystem (IMS) emergency sessions", 3GPP TS 23.167 7.10.0, September 2008. Author's Address Milan Patel Nortel Maidenhead Office Park, Westacott Way Maidenhead, Berkshire, UK Email: milanpa@nortel.com Patel Expires June 19, 2009 [Page 6]
Internet-Draft SOS URI Parameter for SIP Emergency December 2008 Full Copyright Statement Copyright (C) The IETF Trust (2008). This document is subject to the rights, licenses and restrictions contained in BCP 78, and except as set forth therein, the authors retain all their rights. This document and the information contained herein are provided on an "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY, THE IETF TRUST AND THE INTERNET ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. Intellectual Property The IETF takes no position regarding the validity or scope of any Intellectual Property Rights or other rights that might be claimed to pertain to the implementation or use of the technology described in this document or the extent to which any license under such rights might or might not be available; nor does it represent that it has made any independent effort to identify any such rights. Information on the procedures with respect to rights in RFC documents can be found in BCP 78 and BCP 79. Copies of IPR disclosures made to the IETF Secretariat and any assurances of licenses to be made available, or the result of an attempt made to obtain a general license or permission for the use of such proprietary rights by implementers or users of this specification can be obtained from the IETF on-line IPR repository at http://www.ietf.org/ipr. The IETF invites any interested party to bring to its attention any copyrights, patents or patent applications, or other proprietary rights that may cover technology that may be required to implement this standard. Please address the information to the IETF at ietf-ipr@ietf.org. Patel Expires June 19, 2009 [Page 7]