ENUM Working Group J. Livingood Internet-Draft Comcast Cable Communications Expires: January 8, 2006 R. Shockey NeuStar July 2005 IANA Registration for an Enumservice Containing Number Portability and PSTN Signaling Information draft-livingood-shockey-enum-npd-00 Status of this Memo This document is an Internet-Draft and is subject to all provisions of Section 3 of RFC 3667. 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 January 8, 2006. Copyright Notice Copyright (C) The Internet Society (2005). Abstract This document registers the Enumservice ônpdö and subtype ôtelö using the URI scheme ætel:Æ as per the IANA registration process defined in the ENUM specification, RFC 3761. This data is used to facilitate the routing of telephone calls in those countries where Number Portability exists. Livingood & Shockey Expires January 8, 2006 [Page 1] Internet-Draft NPD Enumservice July 2005 Table of Contents 1. Terminology....................................................2 2. Introduction...................................................2 3. ENUM Service Registration for NPD..............................3 4. Examples.......................................................4 4.1 Example of a Ported Telephone Number.......................4 4.2 Example of a Non-Ported Telephone Number...................4 5. Security Considerations........................................5 6. IANA Considerations............................................5 7. Acknowledgements...............................................5 8. References.....................................................6 8.1 Normative References.......................................6 8.2 Informative References.....................................6 AuthorsÆ Addresses................................................7 Intellectual Property and Copyright Statements....................7 1. Terminology 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 [1]. 2. Introduction ENUM (E.164 Number Mapping, RFC 3761 [1]) is a system that transforms E.164 numbers (The International Public Telecommunication Number Plan, ITU-T Recommendation E.164 [2]) into domain names and then uses DNS (Domain Name Service, RFC 1034 [3]) delegation through NS records and NAPTR records (Dynamic Delegation Discovery System (DDDS) Part Three: The Domain Name System (DNS) Database, RFC 3403 [4]) to look up what services are available for a specific domain name. This document registers Enumservices according to the guidelines given in RFC 3761 [1] to be used for provisioning in the services field of a NAPTR [4] resource record to indicate the type of functionality associated with an end point and/or telephone number. The registration is defined within the DDDS (Dynamic Delegation Discovery System [4][5][6][7][8]) hierarchy, for use with the "E2U" DDDS Application defined in RFC 3761. Number portability (NP) allows telephone subscribers to keep their telephone numbers when they change service provider, move to a new location, or change the subscribed services [14]. In many counties, such as the United States and Canada, the functions of naming and addressing on the PSTN have been abstracted. The dialed directory Livingood & Shockey Expires January 8, 2006 [Page 2] Internet-Draft NPD Enumservice July 2005 number is not routable on the PSTN and must be translated into a routing number for call completion. The following Enumservice is registered with this document: "npd" to indicate number portability data. The purpose of this Enumservice is to describe information about telephone numbers which cannot be used on the public Internet or a private/peered Internet Protocol (IP) network. Thus, these are numbers which are only reachable via the traditional Public Switched Telephone Network (PSTN). This Enumservice could enable carriers, as well as other service providers and users, to place ported, pooled, and blocks of numbers and their associated PSTN contact information, into ENUM databases, using standardized, non-proprietary methods. This, in turn, could enable such parties to consolidate all telephone number lookups in their networks into a single ENUM lookup, thereby simplifying call routing and network operations, which would then result in either an on-net, or IP-based response, or off-net, or PSTN-based response. It is conceivable that being able to query for this information in ENUM could significantly reduce or eliminate the need for these parties to maintain traditional, SS7/TCAP/SIGTRAN-based query gateways, applications, and protocols in their networks. The service parameters defined in RFC 3761 dictate that a "type" and a "subtype" should be specified. Within this set of specifications the convention is assumed that the "type" (being the more generic term) defines the service and the "subtype" defines the URI scheme. When only one URI scheme is associated with a given service, it should be assumed that an additional URI scheme to be used with this service may be added at a later time. Thus, the subtype is needed to identify the specific Enumservice intended. In this document, there is one URI scheme specified, 'tel:', as specified in RFC 3966 [9], and as further specified with number portability data in draft-ietf-iptel-tel-np-06.txt [10] (Internet- Draft New Parameters for the "tel" URI to Support Number Portability, draft-ietf-iptel-tel-np-06.txt [10]). 3. ENUM Service Registration for NPD Enumservice Name: "npd" Enumservice Type: "npd" Enumservice Subtype: "tel" URI Scheme: 'tel:' Livingood & Shockey Expires January 8, 2006 [Page 3] Internet-Draft NPD Enumservice July 2005 Functional Specification: This Enumservice indicates that the remote resource identified can be addressed by the associated URI scheme in order to initiate a telecommunication session, which may include two-way voice or other communications, to the PSTN. Security Considerations: See Section 5. Intended Usage: COMMON Authors: Jason Livingood and Richard Shockey (for author contact detail see Authors' Addresses section) Any other information the author deems interesting: None 4. Examples The following sub-sections document several examples for illustrative purposes. These examples shall in no way limit the various forms that this Enumservice may take. 4.1 Example of a Ported Telephone Number $ORIGIN 3.1.8.7.1.8.9.5.1.2.1.e164.arpa. NAPTR 10 100 "u" "E2U+npd:tel" "!^.*$!tel:+1-215-981-7813;rn=+1-215-981-7600;npdi!" In this example, a Routing Number (rn) and a Number Portability Dip Indicator (npdi) are used as shown in draft-ietf-iptel-tel-np-06.txt [10] (Internet-Draft New Parameters for the "tel" URI to Support Number Portability, draft-ietf-iptel-tel-np-06.txt [10]). The ænpdiÆ field is included in order to prevent subsequent lookups in legacy- style PSTN databases. 4.2 Example of a Non-Ported Telephone Number $ORIGIN 3.1.8.7.1.8.9.5.1.2.1.e164.arpa. NAPTR 10 100 "u" "E2U+npd:tel" "!^.*$!tel:+1-215-981-7813;npdi!" In this example, a Number Portability Dip Indicator (npdi) is used [10]. The ænpdiÆ field is included in order to prevent subsequent lookups in legacy-style PSTN databases. Livingood & Shockey Expires January 8, 2006 [Page 4] Internet-Draft NPD Enumservice July 2005 5. Security Considerations DNS, as used by ENUM, is a global, distributed database. Thus any information stored there is visible to anyone anonymously. While this is not qualitatively different from publication in a Telephone Directory, it does open or ease access to such data without any indication that such data has been accessed or by whom it has been accessed. Such data harvesting by third parties is often used to generate lists of targets for unsolicited information. Thus, a third party could use this to generate a list that they can use to make unsolicited "telemarketing" phone calls. Many countries have do-not-call registries or other legal or regulatory mechanisms in place to deal with such abuses. Carriers, service providers, and other users may simply choose not to publish such information in the public E164.ARPA tree, but may instead simply publish this in their internal ENUM routing database which is only able to be queried by trusted elements of their network, such as softswitches and SIP proxy servers. Although an E.164 telephone number does not appear to reveal as much identity information about a user as a name in the format username@hostname (e.g., an email or SIP address), the information is still publicly available, thus there is still the risk of unwanted communication. An analysis of threats specific to the dependence of ENUM on the DNS and the applicability of DNSSEC [12] to this is provided in RFC 3761 [1]. A thorough analysis of threats to the DNS itself is covered in RFC 3833 [13]. DNS does not make any policy decisions about the records that it shares with an inquirer. All DNS records must be assumed to be available to all inquirers at all times. The information provided within an ENUM NAPTR resource record must therefore be considered to be open to the public, unless otherwise secured through split-DNS or some other method, which is a cause for some privacy considerations. 6. IANA Considerations This document registers the 'npd' Enumservice and the subtype ôtelö under the Enumservice registry described in the IANA considerations in RFC 3761. Details of this registration are provided in sections 3 and 4 of this document. 7. Acknowledgements Livingood & Shockey Expires January 8, 2006 [Page 5] Internet-Draft NPD Enumservice July 2005 The authors wish to thank Tom Creighton, Jason Gaedtke, Jaime Jimenez, and Chris Kennedy from Comcast Cable, Jonathan Rosenberg from Cisco, and James Yu from NeuStar, for their helpful discussion on this topic. 8. References 8.1 Normative References [1] Faltstrom, P. and M. Mealling, "The E.164 to Uniform Resource Identifiers (URI) Dynamic Delegation Discovery System (DDDS) Application (ENUM)", RFC 3761, April 2004. [2] ITU-T, "The International Public Telecommunication Number Plan", Recommendation E.164, May 1997. [3] Mockapetris, P., "DOMAIN NAMES - CONCEPTS AND FACILITIES", RFC 1034, November 1987. [4] Mealling, M., "Dynamic Delegation Discovery System (DDDS) Part Three: The Domain Name System (DNS) Database", RFC 3403, October 2002. [5] Mealling, M., "Dynamic Delegation Discovery System (DDDS) Part One: The Comprehensive DDDS", RFC 3401, October 2002. [6] Mealling, M., "Dynamic Delegation Discovery System (DDDS) Part Two: The Algorithm", RFC 3402, October 2002. [7] Mealling, M., "Dynamic Delegation Discovery System (DDDS) Part Four: The Uniform Resource Identifiers (URI)", RFC 3404, October 2002. [8] Mealling, M., "Dynamic Delegation Discovery System (DDDS) Part Five: URI.ARPA Assignment Procedures", RFC 3405, October 2002. [9] Schulzrinne, H., "The tel URI for Telephone Numbers", RFC 3966, December 2004. [10] Yu, J., "New Parameters for the "tel" URI to Support Number Portability", draft-ietf-iptel-tel-np-06.txt, June 2005. 8.2 Informative References [11] Bradner, et al., "IANA Registration for Enumservices email, fax, mms, ems and sms", draft-ietf-enum-msg-05.txt, May 2005. Livingood & Shockey Expires January 8, 2006 [Page 6] Internet-Draft NPD Enumservice July 2005 [12] Arends, R. and et al., "Protocol Modifications for the DNS Security Extensions", RFC 4035, March 2005. [13] Atkins, D. and R. Austein, "Threat Analysis of the Domain Name System (DNS)", RFC 3833, August 2004. [14] M. Foster, T. McGarry and J. Yu, "Number Portability in the GSTN: An Overview", RFC 3482, February 2003. AuthorsÆ Addresses Jason Livingood Comcast Cable Communications 1500 Market Street Philadelphia, PA 19102 USA Phone: +1-215-981-7813 Email: jason_livingood@cable.comcast.com Richard Shockey NeuStar 46000 Center Oak Plaza Sterling, VA 20166 USA Phone: +1-571-434-5651 Email: richard.shockey@neustar.biz Intellectual Property and Copyright Statements 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 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. Acknowledgment Funding for the RFC Editor function is currently provided by the Internet Society. Livingood & Shockey Expires January 8, 2006 [Page 8]