SIPPING WG Rocky Wang, Ed. Internet Draft Youzhu Shi Expires: April 15, 2006 Huawei Technologies October 13, 2005 A header to deliver the calling party category draft-rocky-sipping-calling-party-category-00.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 April 15, 2006. Copyright Notice Copyright (C) The Internet Society (2005). Abstract SS7 ISUP [3] defines a Calling Party's Category (CPC) parameter that characterizes the station used to originate a call and carries other important state that can describe the originating party. Based on the CPC parameter from the calling network, the called network can do some special processes related to the calling party category, just like override the calee's DND and some other barring services. Rocky Expires - April 2006 [Page 1] Internet-Draft Calling party category in SIP October 2005 This document specifies a way to deliver the calling party category to implement some supplementary services derived from the PSTN network. Table of Contents 1. Introduction...................................................2 2. Conventions....................................................3 3. The P-CPC header field.........................................3 4. Usage..........................................................4 5. Security Considerations........................................5 6. IANA Considerations............................................5 7. References.....................................................5 7.1 Normative References........................................5 7.2 Informational References....................................5 Acknowledgment....................................................6 Author's Address..................................................6 Intellectual Property Statement...................................6 Disclaimer of Validity............................................7 Copyright Statement...............................................7 1. Introduction The Do Not Disturb (DND) supplementary service allows the served user to instruct the network to automatically reject incoming calls because he does not want to be disturbed. The Anonymous Call Rejection (ACR) supplementary service allows the served user to reject incoming calls from users or subscribers who have restricted the presentation of their calling party identifier. DND and ACR are popular supplementary services in the public switch telephone network (PSTN) and have already been used by a great number of subscribers. But there are some provisions for exceptional cases that the calling party should have the opportunity to override the DND or ACR service to reach the called party even though the services are activated and the service-specific conditions are met. For an instance, a call from a police station, emergency call center or from an operator who has the rights to override the served user's services. SS7 ISUP [3] defines a Calling Party's Category (CPC) parameter that characterizes the station used to originate a call and carries other important state that can describe the originating party. Based on the CPC parameter from the calling network, the called network can do some special processes related to the calling party category, just like the cases described above. Rocky Expires - April 2006 [Page 2] Internet-Draft Calling party category in SIP October 2005 This document defines a new header to deliver the calling party category. The draft [8] defines a URI parameter, "cpc", to deliver the CPC parameter. But the calling party category is always required to be considered as a part of the caller's profile or subscription. That is, the calling network must know the detail of it and it must be asserted by the network if it is provided by the calling party station. So, it is better that only the network equipments add, remove or read and process it, and in this case it is better to deliver such a parameter by a separated header field. 2. Conventions The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in BCP 14, RFC 2119 [4]. 3. The P-CPC header field The P-CPC header field MAY appear in any request out of a dialog. The syntax of the header field follows the standard SIP header syntax. P-CPC = "P-CPC" HCOLON cpc-value *( SEMI cpc-param ) cpc-value = "ordinary" / "operator" / "test" / "payphone" / "prison" / "hotel" / "hospital" / "police" / "cellular" / "cellular-roaming" / "freecharge" / "data" / "unknown" / token cpc-param = cpc-pname [ "=" cpc-pvalue ] cpc-pname = 1*paramchar cpc-pvalue = 1*paramchar The "paramchar" is defined in RFC3261 [1]. The semantics of these Calling Party Category values are described below: ordinary: The caller has been identified, and has no special features. operator: The call was generated by an operator position. test: This is a test call that has been originated as part of a maintenance procedure. payphone: The calling station is a payphone. prison: The calling station is in a prison. hotel: The calling station is in a hotel or motel. hospital: The calling station is in a medical facility. police: The calling station is associated with a branch of law enforcement. cellular: The calling station is a radio-telephone operating in Rocky Expires - April 2006 [Page 3] Internet-Draft Calling party category in SIP October 2005 its home network. cellular-roaming: The calling station is a radio-telephone roaming in another network freecharge: The caller is a free-charge subscriber. data: The calling station is a data station. unknown: The CPC could not be ascertained. To enables the network received the P-CPC header do some special process based on the calling party category, the P-CPC header is should only appear in the request message out of a dialog. 4. Usage The calling party category is always related to the caller service profile or subscription, that’s why only the network server should be responsible for keeping and providing this information to all the others who need it. Because the network server is responsible for setting/adding the P- CPC header, this operation cannot be performed by the calling user endpoints. This calling party category information belongs to the caller's profile and if provided by the caller endpoint it must be asserted by the originating network. Because of the need for strict authenticity of this header, it is recommended that only the network server should be able to add, remove and process it, through an independent header field. After receiving the request from the caller endpoint, the network server should add the P-CPC header into the request before it is transferred across to the called network. When a network server receives this request from another network server and the P-CPC header field is found to be absent. In this case the receiving network server would consider the calling party category of this request as "ordinary" by default To ensure trusted behavior in the system, the caller network server must overwrite any existing P-CPC header in the incoming request from the caller's endpoint. Rocky Expires - April 2006 [Page 4] Internet-Draft Calling party category in SIP October 2005 Once the request reaches the called party network, the called party network server can do some special processing related to the calling party category information, for example implementing the DND and ACR override by the caller if his category is "police". The calling party category information is sensitive and the called network server should remove it and ensure this information is not transferred to the called user endpoint. 5. Security Considerations The information contained in the P-CPC header may be of a private nature, and it may not be appropriate for this value to be revealed to the destination user (typically it would not be so revealed in the PSTN). To reach this, before sending the request to the called party endpoint, the server, any logical entity it is, should remove this header and maybe some other sensitive information also. Otherwise, this mechanism adds no new security considerations to those discussed in [1]. 6. IANA Considerations This extension defines a new header field: Name of Header: P-CPC Short form: none Normative description: section 3 of this document 7. References 7.1 Normative References [1] 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. [2] Crocker, D. and P. Overell, "Augmented BNF for Syntax Specifications: ABNF", RFC 2234, November 1997. [3] International Telecommunications Union, "Recommendation Q.763: Signalling System No. 7: ISDN user part formats and codes", December 1999, . [4] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. 7.2 Informational References [5] Peterson, J., "A Privacy Mechanism for the Session Initiation Rocky Expires - April 2006 [Page 5] Internet-Draft Calling party category in SIP October 2005 Protocol (SIP)", RFC 3323, November 2002. [6] American National Standards Institute, "ANSI T1.113-2000, Signaling System No. 7, ISDN User Part", 2000, . [7] ETSI, "Services and Protocols for Advanced Networks (SPAN); Anonymous Call Rejection (ACR) Supplementary Service; Service description", ETSI EN 301 798 v1.1.1, October 2000, . [8] Rohan Mahy, "The Calling Party's Category tel URI Parameter", draft-mahy-iptel-cpc-02 (work in progress), February 21, 2005. Acknowledgment We would like to thank Rohan Mahy for his draft giveing us some idea to resolve the problem under some circumstances. We also thank Peili Xu, Smile Wang, Qing Zhou, Mukund and Prasanna for providing useful comments. Author's Address Rocky Wang (Editor) Huawei Technologies Co., Ltd. Huadian Building, Bantian, Longgang District, Shenzhen 518129 P.R.C. EMail: rocky.wang@huawei.com Youzhu Shi Huawei Technologies Co., Ltd. Huadian Building, Bantian, Longgang District, Shenzhen 518129 P.R.C. EMail: cainong@huawei.com Intellectual Property Statement 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 Rocky Expires - April 2006 [Page 6] Internet-Draft Calling party category in SIP October 2005 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. 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Disclaimer of Validity 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 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. Copyright Statement Copyright (C) The Internet Society (2005). 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. Rocky Expires - April 2006 [Page 7]