ENUM Working Group J. Livingood
Internet-Draft Comcast Cable Communications
Expires: January 31, 2008 P. Pfautz
AT&T
R. Stastny
Oefeg
July 2007
The E.164 to Uniform Resource Identifiers (URI)
Dynamic Delegation Discovery System (DDDS) Application for
Infrastructure ENUM
draft-ietf-enum-infrastructure-06
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Copyright (C) The IETF Trust (2007).
Abstract
This document defines the use case for Infrastructure ENUM and
proposes its implementation as a parallel namespace to "e164.arpa" as
defined in RFC3761, as the long-term solution to the problem of
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allowing carriers to provision DNS records for telephone numbers
independently of those provisioned by end users (number assignees).
Table of Contents
1. Terminology....................................................2
2. Introduction...................................................2
3. Zone Apex for Infrastructure ENUM..............................3
4. IANA Considerations............................................3
5. Security and Privacy Considerations............................3
6. Acknowledgements...............................................4
7. References.....................................................4
7.1 Normative References.......................................4
7.2 Informative References.....................................4
Authors' Addresses................................................4
Intellectual Property and Copyright Statements....................5
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 [5].
2. Introduction
ENUM (E.164 Number Mapping, RFC 3761 [1]) is a system that transforms
E.164 numbers [2] into domain names and then uses the DNS (Domain
Name Service) [3] to discover NAPTR records that specify what
services are available for a specific domain name.
ENUM as originally defined was based on the end-user opt-in
principle. While this has great potential to foster new services and
end-user choice in the long-term, the current requirements for IP-
based interconnection of Voice over IP (VoIP) domains require the
provisioning of large numbers of allocated or served (hosted) numbers
of a participating service provider, without the need for individual
users to opt-in or not and so that service providers can provision
their own ENUM information that is separate, distinct, and likely to
be different from what and end-user may provision. This is
particularly important if Infrastructure ENUM is used for number
portability applications, for example, which an end-user would be
unlikely to be interested in provisioning but which a service
provider would likely find essential.
In addition, while it is possible that service providers could
mandate that their users opt-in into e164.arpa through end-user
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contract terms and conditions, there are substantial downsides to
such an approach. Thus, for all these reasons and many others, ENUM
for end-user provisioning is ill-suited for use by service providers
for the interconnection of VoIP domains.
As VoIP evolves and becomes pervasive, E.164-addressed telephone
calls need not necessarily traverse the Public Switched Telephone
Network (PSTN). Therefore, VoIP service providers have an interest
in using ENUM, on a so-called "Infrastructure" basis, to keep VoIP
traffic on IP networks on an end-to-end basis, both within and
between service provider domains. This requires of means of
identifying a VoIP point of interconnection to which calls addressed
to a given E.164 number may be delivered and Infrastructure ENUM
provides this means. Calls that can originate and terminate on IP
networks, and not have to traverse the PSTN, will require fewer or no
points of transcoding, and can also involve additional IP network
services that are not possible on the PSTN, among other benefits.
Requirements for Infrastructure ENUM are provided in[4].
This document defines that Infrastructure ENUM be implemented by
means of a parallel namespace to e164.arpa dedicated to
Infrastructure ENUM, in a domain which is to be determined. Use of a
parallel namespace allows carriers and end users to control their
ENUM registrations for a number independently without forcing one to
work through the other.
Infrastructure ENUM Tier 2 resource records in the Infrastructure
ENUM tree would be controlled by the service provider that is
providing services to a given E.164 number, generally referred to in
various nations as the "carrier of record" (see [4]). The definition
of a carrier of record for a given E.164 number is a national matter
or is defined by the entity controlling the numbering space.
3. Zone Apex for Infrastructure ENUM
See Section 3, Requirements, in [4].
4. IANA Considerations
This document contains no requested IANA actions.
IANA has created a registry for Enumservices as originally specified
in RFC 2916 and revised in RFC 3761. Enumservices registered with
IANA are valid for Infrastructure ENUM as well as end-user ENUM.
5. Security and Privacy Considerations
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See Section 4, Security Considerations, in [4].
6. Acknowledgements
The authors wish to thank Lawrence Conroy, Patrik Faltstrom, Michael
Haberler, Otmar Lendl, Steve Lind, Alexander Mayrhofer, Jim Reid, and
Richard Shockey for their helpful discussion of this draft and the
concept of Infrastructure ENUM.
7. References
7.1 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, February 2005.
[3] Mockapetris, P., "DOMAIN NAMES - CONCEPTS AND FACILITIES", RFC
1034, November 1987.
[4] Lind, S., Pfautz, P., "Infrastructure ENUM Requirements", draft-
ietf-enum-infrastructure-enum-reqs-04, May 2007.
[5] Bradner, S., "Key words for use in RFCs to Indicate Requirement
Levels", RFC 2119, March 1997.
7.2 Informative References
[6] Bush, R., Karrenberg, D., Kosters, M., Plzak, R., "Root Name
Server Operational Requirements", RFC 2870, June 2000.
Authors' Addresses
Jason Livingood
Comcast Cable Communications
1500 Market Street
Philadelphia, PA 19102
USA
Phone: +1-215-981-7813
Email: jason_livingood@cable.comcast.com
Penn Pfautz
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Internet-Draft Infrastructure ENUM July 2007
AT&T
200 S. Laurel Ave
Middletown, NJ 07748
USA
Phone: +1-732-420-4962
Email: ppfautz@att.com
Richard Stastny
Oefeg
Postbox 147
1103 Vienna
Austria
Phone: +43-664-420-4100
Email: Richard.stastny@oefeg.at
Intellectual Property and Copyright Statements
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