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
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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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