SIPPING D. York Internet-Draft Voxeo Intended status: Informational T. Asveren Expires: August 24, 2008 Sonus February 21, 2008 P-Charge-Info - A Private Header (P-Header) Extension to the Session Initiation Protocol (SIP) draft-york-sipping-p-charge-info-01 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 August 24, 2008. Copyright Notice Copyright (C) The IETF Trust (2008). Abstract This document describes 'P-Charge-Info', a private Session Initiation Protocol (SIP) header (P-header) used by a number of equipment vendors and carriers to convey simple billing information. York & Asveren Expires August 24, 2008 [Page 1] Internet-Draft P-Charge-Info, a SIP Private Header February 2008 Table of Contents 1. Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Requirements Language . . . . . . . . . . . . . . . . . . . . . 4 3. The P-Charge-Info Header . . . . . . . . . . . . . . . . . . . 4 3.1. Applicability Statement for the P-Charge-Info header . . . 4 3.2. Usage of the P-Charge-Info header . . . . . . . . . . . . . 4 3.2.1. Procedures at the UA . . . . . . . . . . . . . . . . . 4 3.2.2. Procedures at the Proxy . . . . . . . . . . . . . . . . 4 3.3. Examples of Usage . . . . . . . . . . . . . . . . . . . . . 4 4. Formal Syntax . . . . . . . . . . . . . . . . . . . . . . . . . 5 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 5 6. Security Considerations . . . . . . . . . . . . . . . . . . . . 6 7. References . . . . . . . . . . . . . . . . . . . . . . . . . . 6 7.1. Normative References . . . . . . . . . . . . . . . . . . . 6 7.2. Informative References . . . . . . . . . . . . . . . . . . 6 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 6 Intellectual Property and Copyright Statements . . . . . . . . . . 8 York & Asveren Expires August 24, 2008 [Page 2] Internet-Draft P-Charge-Info, a SIP Private Header February 2008 1. Overview In certain network configurations, it is desirable to decouple the Caller ID from the number used for billing purposes. This document describes the current usage of 'P-Charge-Info', a private SIP header, to provide simple billing information and requests the registration of this header with IANA as required by section 4.1 of RFC 3427 [RFC3427]. In a typical configuration, "Caller ID" is derived from one of the following SIP headers: o Remote-Party-ID o P-Asserted-Identity o From (in the absence of the other two) This number is typically presented to the receiving UA where it is usually displayed for the end user. It is also typically used for billing purposes by the network entities involved in carrying the session. However, in a distributed environment the "Caller ID" presented to the receiving UA may not reflect the actual reality of the underlying network in terms of costs incurred on the PSTN. This may result in excessive charging of one carrier by another based on the erroneous assumption that the call was originating from a different point on the PSTN. There exists a need for a way to pass an additional billing identifier that can be used between network entities in order to correctly bill for services. At least one equipment provider, Sonus Networks, and several carriers have been using the "P-Charge-Info" header for the last 2-3 years as a simple mechanism to exchange this billing identifier. It should be noted that the 3GPP has also recognized the need for such a billing identifier and in section 4.6 of RFC 3455 [RFC3455] established a SIP P-Header, "P-Charging-Vector", to provide similar information. This header, though, is designed for use within 3GPP environments and thus includes parameters appropriate within a 3GPP context. It also allows for the use of any general value as the billing identifier whereas P-Charge-Info, as noted below, specifically requires a SIP URI as the content. York & Asveren Expires August 24, 2008 [Page 3] Internet-Draft P-Charge-Info, a SIP Private Header February 2008 2. Requirements Language 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 RFC 2119. 3. The P-Charge-Info Header 3.1. Applicability Statement for the P-Charge-Info header The P-Charge-Info header is applicable within a single private administrative domain or between different administrative domains where there is a trust relationship between the domains. 3.2. Usage of the P-Charge-Info header The P-Charge-Info header is used to convey information related to billing record for a particular call. The P-Charge-Info header is typically inserted by the SIP proxy on the originating network. 3.2.1. Procedures at the UA The P-Charge-Info header may be inserted by PSTN gateways acting as a SIP UA, either through local policy or as a result of information received via PSTN signaling, e.g. the charge parameter in an ISUP IAM message. The P-Charge-Info header is not used/interpreted by a regular (i.e. non-gateway) UA and should not normally be seen by such a UA. If the header is transmitted to such a UA, the UA should ignore the header. 3.2.2. Procedures at the Proxy A SIP proxy that supports this extension and receives a request, typically a SIP INVITE, without the P-Charge-Info header MAY insert a P-Charge-Info header. The contents of the inserted header may be decided based on local policy or by querying an external entity. A SIP proxy that does not support this extension will pass any received P-Charge-Info header unmodified in compliance with RFC 3261. 3.3. Examples of Usage The content of the P-Charge-Info header is typically simply a SIP URI used as a billing indicator. As such, an example would be as simple as: York & Asveren Expires August 24, 2008 [Page 4] Internet-Draft P-Charge-Info, a SIP Private Header February 2008 P-Charge-Info: Any other applicable SIP URI could be used. P-Charge-Info optionally includes the numbering plan indicator as an additional parameter. This is used when an ISUP message is built from a SIP message for scenarios where SIP is used to connect two PSTN segments and needs to pass charging information between them. An example of the usage of the optional header is: P-Charge-Info: 4. Formal Syntax The Private Header specified in this document is described in both prose and an augmented Backus-Naur Form (BNF) defined in RFC 2234. Further, several BNF definitions are inherited from SIP and are not repeated here. Implementors need to be familiar with the notation and contents of SIP [1] and RFC 2234 [3] to understand this document. The syntax of the P-Charge-Info header is described as follows: P-Charge-Info = "P-Charge-Info" HCOLON charge-param * (SEMI charge-param) charge-param = (addr-spec) * (SEMI charge-params) charge-params = (("npi" EQUAL npi-value)) npi-value = ("ISDN" / "DATA" / "TELEX" / "PRIVATE" / "SPARE0" / "SPARE1" / "SPARE2" / "SPARE3" / "SPARE4" / "SPARE5" / "SPARE6" / "SPARE7" ) 5. IANA Considerations This document defines a private SIP extension header field (beginning with the prefixe "P-"). The extension is registered as a private extension field: RFC Number: RFCXXXX [Note to IANA: Please fill in with the RFC number of this specification. Header Field Name: P-Charge-Info Compact Form: none York & Asveren Expires August 24, 2008 [Page 5] Internet-Draft P-Charge-Info, a SIP Private Header February 2008 6. Security Considerations Given that the information contained in the P-Charge-Info header will be used for billing purposes the proxies that share this information MUST have a trust relationship. If an untrusted entity were inserted between the trusted entities, it could potentially interfere with the billing records for the call. If the SIP connections are not made over a private WAN, a mechanism for securing the confidentiality and integrity of the SIP connection should be used to protect the information. 7. References 7.1. Normative References [RFC3427] Mankin, A., Bradner, S., Mahy, R., Willis, D., Ott, J., and B. Rosen, "Change Process for the Session Initiation Protocol (SIP)", BCP 67, RFC 3427, December 2002. 7.2. Informative References [RFC3455] Garcia-Martin, M., Henrikson, E., and D. Mills, "Private Header (P-Header) Extensions to the Session Initiation Protocol (SIP) for the 3rd-Generation Partnership Project (3GPP)", RFC 3455, January 2003. Authors' Addresses Dan York Voxeo Corporation Burlington, VT USA Phone: +1-407-455-5859 Email: dyork@voxeo.com URI: http://www.voxeo.com/ York & Asveren Expires August 24, 2008 [Page 6] Internet-Draft P-Charge-Info, a SIP Private Header February 2008 Tolga Asveren Sonus Networks 3 Paragon Way Freehold, NJ 07728 USA Email: tasveren@sonusnet.com York & Asveren Expires August 24, 2008 [Page 7] Internet-Draft P-Charge-Info, a SIP Private Header February 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. 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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. Acknowledgment Funding for the RFC Editor function is provided by the IETF Administrative Support Activity (IASA). York & Asveren Expires August 24, 2008 [Page 8]