    Network Working Group                                          K. Toyoda
    Request for Comments: 4143                                           PCC
    Category: Standards Track                                     D. Crocker
                                                                 Brandenburg
                                                               November 2005

              Facsimile Using Internet Mail (IFAX) Service of ENUM

    Status of This Memo

       This document specifies an Internet standards track protocol for the
       Internet community, and requests discussion and suggestions for
       improvements.  Please refer to the current edition of the "Internet
       Official Protocol Standards" (STD 1) for the standardization state
       and status of this protocol.  Distribution of this memo is unlimited.

    Copyright Notice

       Copyright (C) The Internet Society (2005).

    Abstract

       This document describes the functional specification and definition
       of the ENUM Naming Authority Pointer (NAPTR) record for IFax service.
       IFax is "facsimile using Internet mail".  For this use, the Domain
       Name System (DNS) returns the email address of the referenced IFax
       system.  This mechanism allows email-based fax communication to use
       telephone numbers instead of requiring the sender to already know the
       recipient email address.

    1.   Functional Specification

       An IFax client makes a [ENUMbis] DNS query, using the target system's
       telephone number.  The returned NAPTR record specifies an email
       address to be used for reaching the target system.  The email address
       is then used in accordance with Simple Mode of Facsimile using
       Internet Mail [RFC3965], Extended Facsimile using Internet Mail
       [RFC2532], or Full Mode Fax Profile for Internet Mail [FFPIM] is
       applied.

       The key words "MUST", "MUST NOT", "SHOULD", "SHOULD NOT", and "MAY"
       in this document are to be interpreted as defined in "Key words for
       use in RFCs to Indicate Requirement Levels" [KEYWORDS].

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    RFC 4143                  IFAX service of ENUM             November 2005

    2.  IFax Service Registration

       Service Name : "E2U+ifax"

       Type: "ifax"

       Subtype: "mailto"

       URI Scheme: "mailto"
       The URI Scheme is "mailto" because facsimile is a profile of standard
       Internet mail and uses standard Internet mail addressing.

       Functional Specification: See section 1

       Security Considerations: See section 3

       Intended usage: COMMON

       Author: Kiyoshi Toyoda (toyoda.kiyoshi@jp.panasonic.com)
               Dave Crocker (dcrocker@bbiw.net)

    3.  Security Considerations

       DNS, as used by ENUM, is a globally distributed database.  Thus, any
       information stored in it is visible to anyone anonymously.  Although
       this is not qualitatively different from publication in a telephone
       directory, it does expose the data subject to automatic data
       collection without any indication that this has been done or by whom.

       Data harvesting by third parties is often used to generate lists of
       targets for unrequested information; in short, the lists are used to
       address "spam".  The publication of a telephone number in ENUM,
       especially when it is an associated Internet fax service, may be used
       to send "junk faxes", for example.

       In the case of electronic mail, users subscribed to mailing lists can
       have "sacrificial" email accounts.  These special-purpose addresses
       help the user filter out unrequested email.  This is not so easy with
       published telephone numbers.  The PSTN E.164 number assignment
       process is much more involved and less flexible; usually a single
       E.164 number (or a fixed range of numbers) is associated with each
       PSTN access.  Thus, it is not possible to use a "sacrificial" phone
       number.

       Due to the implications of publishing data in a globally accessible
       database, as a principle, the data subject MUST give explicit
       informed consent to data being published in ENUM.

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    RFC 4143                  IFAX service of ENUM             November 2005

       Internet Fax is based on existing use of Internet mail.  Developers
       and users should also consider the Security Consideration sections in
       [RFC3965] and [RFC2532].

       In addition to the specific security considerations given above, the
       Security Considerations section of [ENUMbis] applies to this
       document.

    4.  Example

       The following is an example of the use of IFax service in a NAPTR
       record.

          $ORIGIN 4.3.2.1.6.7.9.8.6.4.e164.arpa
            IN NAPTR 10 10 "u" "E2U+ifax:mailto"
                                   "!^.*$!mailto:toyo@example.com!"

    5.  IANA Considerations

       This specification creates a DNS NAPTR registration, according to the
       terms specified in [ENUMbis].

       The registration details are contained in section 2, Fax Service
       Registration.

    6.  References

    6.1.  Normative References

       [KEYWORDS] Bradner, S., "Key words for use in RFCs to Indicate
                  Requirement Levels", BCP 14, RFC 2119, March 1997.

       [ENUMbis]  Faltstrom, P. and M. Mealling, "The E.164 to Uniform
                  Resource Identifiers (URI) Dynamic Delegation Discovery
                  System (DDDS) Application (ENUM)", RFC 3761, April 2004.

       [RFC3965]  Toyoda, K., Ohno, H., Murai, J., and D. Wing, "A Simple
                  Mode of Facsimile Using Internet Mail", RFC 3965, December
                  2004.

       [RFC2532]  Masinter, L. and D. Wing, " Extended Facsimile Using
                  Internet Mail", RFC 2532, March 1999.

       [FFPIM]    Crocker, D. and G. Klyne, "Full-mode Fax Profile for
                  Internet Mail (FFPIM)", RFC 4142, November 2005.

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    RFC 4143                  IFAX service of ENUM             November 2005

    Authors' Addresses

       Kiyoshi Toyoda
       Research and Development Laboratory
       Panasonic Communications Co., Ltd.
       4-1-62 Minoshima Hakata-ku, Fukuoka 812-8531 Japan

       Phone: +81-50-3380-5181
       EMail: toyoda.kiyoshi@jp.panasonic.com

       Dave Crocker
       Brandenburg InternetWorking
       675 Spruce Drive
       Sunnyvale, CA  94086  USA

       Phone: +1.408.246.8253
       EMail: dcrocker@bbiw.net

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    RFC 4143                  IFAX service of ENUM             November 2005

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    Acknowledgement

       Funding for the RFC Editor function is currently provided by the
       Internet Society.

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