Telephone Number Mapping A. Brown Internet Draft Nortel Networks Document: June 2000 Category: Informational ENUM Requirements Status of this Memo This document is an Internet-Draft and is in full conformance with all provisions of Section 10 of RFC2026 [1]. 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. 1. Abstract This paper defines the requirements for a DNS-based architecture and protocols for mapping a telephone number to a set of attributes (e.g., URLs) that can be used to contact a resource associated with that number. There are many possible protocols that can be considered for a telephone number mapping service. The purpose of this document is to focus discussion on a DNS-based solution. The intention is to enumerate the expectations of such a solution and to clarify the scope. 2. Conventions used in this document 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 [2]. 3. Requirements 3.1 Endpoint Address Lookup The system SHALL provide a service for the retrieval of service specific endpoint addresses (e.g., email address, IP address, SIP address, URL, etc.) or the retrieval of the addresses of servers, if available, which may contain this endpoint information. ENUM Requirements June 2000 3.2 Capabilities Retrieval/Negotiation The retrieval or negotiation of capabilities is beyond the scope of the system. 3.3 Retrieval of Additional Information and Capabilities The retrieval of additional, application-specific information (e.g., spoken name for verification purposes) is beyond the scope of the system. The system MUST provide a service for the retrieval of protocol and service information if available. The system SHOULD provide access to capabilities relevant to the telephone number in question. The retrieval or negotiation of capabilities will depend on the outcome of the rescap work or work done in other groups. 3.4 Qualification of the Request The system is not required to enable the qualification of a request by a user, for the purposes of filtering for reducing returned information or for traffic reduction. 3.5 Provisioning The architecture and protocol MAY support at least the existing administrative model as the current E.164 telephone number delegation system. The protocol SHOULD also provide the ability to support corporate numbering plan or competitive directory service providers under separate root domains. It SHOULD NOT require an additional centralized administrator beyond that required for the existing telephone number system. The distribution of telephone numbers is a national affair by ITU treaty and different telephone number distribution schemes may require different delegation models. How nations choose to administer the ENUM space within their borders is a national issue. In any case, the subscriber or enterprise is the ultimate authority for service provisioning. Further, it must be possible for the authority to which a telephone number has been delegated to redirect the query to a different entity that provides service-specific information for that number. 3.6 Propagation of Changes Propagation of Changes If multiple copies of the data are distributed in different areas, their update should be incorporated almost simultaneously depending on the application of DNS to services. ENUM Requirements June 2000 When a numbering plan change is made in a country or network, the update of relevant E.164 number data in DNS needs to be coordinated with the change. 3.7 Response Timeout The system SHALL have a defined timeout mechanism. 3.8 Global Number Portability The system MUST support existing local number portability mechanisms, where applicable. It is RECOMMENDED that the system not be designed in such as way as to impede future global number portability. 3.9 Scalability The system MUST scale to handle quantities of telephone numbers and queries comparable to current and expected future PSTN usage. It must be possible to operate the system based on telephone number blocks defined at the digit boundaries as well as explicit per- number configuration. 3.10 Query Performance It SHOULD be possible to administer the ENUM service using the selected protocols and structures such that the current user expectations for latency in telecommunications services can be met. In particular, it SHOULD be possible to operate the system in such a manner that an ENUM query for a service-specific record can be satisfied within one second 95% of the time and that within two seconds, the query can be satisfied 99% of the time. 3.11 Other PSTN Numbering Services E.164 numbers, short codes, service codes and prefixes are categorized in dialing plans. A prefix is an indicator consisting of one or more digits that allows the selection of different types of number formats, networks and/or services. Prefixes are not part of the number and are part of a dialing plan. The uses and the formats of prefixes are a national matter. Short codes, e.g. emergency, or service codes may be used based on the national numbering plan. Those codes are not universal and typically valid only within a numbering domain identified with the same country code or country code + network identification code. PSTN type numbering services such as Emergency 911, directory assistance 411, and other carrier codes for services accessible via non-E164 (or subset) telephone number service access codes are outside the scope of ENUM. 3.12 Privacy ENUM Requirements June 2000 The system MUST allow the owner of the telephone number to control the information which prospective callers may receive. 3.13 Competition The solution MUST permit competing service providers to offer telecommunications service for a given number. Competing telecommunications services MUST be enabled where the ENUM entry is administered by the single entity to which the number is delegated. Who that single entity is, is beyond the scope of ENUM. 3.14 Authorization of Requests and Responses The system SHALL enable the authorization of requests and responses. 3.15 Privacy and Integrity of Requests and Responses The system SHALL enable the privacy and integrity of requests and responses. 3.16 Call Routing The system is not required to provide a service for routing calls or locating gateways to a specific service. 3.17 Service Logic The system is not responsible for employing service logic for the intelligent retrieval of information. 3.18 E.164 Numbers The system is not responsible for returning information on private numbering plans and non-E.164 numbers. The system is responsible for returning information on 1-800 and other legitimate E.164 numbers. 3.19 Application Specific Use of ENUM The ENUM service MUST be application agnostic. It is expected that various other IETF work groups will develop ENUM specific usage profiles for their specific application. ENUM will not mandate the use of any specific DNS Resource Record for any particular application. 4. Security Considerations This document specifies several security requirements including privacy of information, and authorization, privacy and integrity or requests and responses. ENUM Requirements June 2000 The system will be designed to retrieve information required to initiate an Internet telephony session. Each of these session types will have their own security threats, which should be addressed in the groups responsible for those services. 5. References 1 Bradner, S., "The Internet Standards Process -- Revision 3", BCP 9, RFC 2026, October 1996. 2 Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997 6. Acknowledgements This document is based on discussions from the ENUM working group. 7. Author's Addresses Anne Brown Nortel Networks P.O. Box 3511, Station C K1Y 4H7 Phone: +1 613 765 5274 Email: arbrown@nortelnetworks.com 8. Changes From draft-enum-rqmts-00.txt Based on WG discussions and input documents from the SG2 workshop, the following changes have been made since the previous version of this draft: 3.1 Endpoint Address Lookup Major - URLs are not the only response 3.3 Retrieval of Additional Information and Capabilities Renamed from "Retrieval of Additional Information" Minor - Added paragraph on capabilities 3.5 Provisioning Major - New text involving change of ENUM scope 3.6 Propagation of Changes New section Major - New section based on nnar-e164-dns-iw-info.txt 3.9 Scalability Renumbered from 3.8 Major - New paragraph on handling of both blocks and individual telephone numbers. 3.10 Query Performance Renumbered from 3.9 Major - Upgraded to support PSTN performance expectations 3.11 Other PSTN Numbering Services Renumbered from 3.10 ENUM Requirements June 2000 Renamed from "Other PSTN Services" Minor - Changes for clarification based on WG discussions and nnar-e164-dns-iw-info.txt 3.13 Competition Renumbered from 3.12 Major - Telephone number MUST be able to be administered by a single entity 3.19 Application Specific Use of ENUM New Section Major - For clarification Full Copyright Statement "Copyright (C) The Internet Society (date). 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