
Telephone Number Mapping                                       A. Brown
Internet Draft                                          Nortel Networks
Document: <draft-ietf-enum-rqmts-01.txt>                      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].

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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

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