
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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