Internet DRAFT - draft-gallant-enum-ifax
draft-gallant-enum-ifax
Individual Submission A. Gallant
Internet Draft NeuStar, Inc.
Document: <draft-gallant-enum-ifax-01.txt> November 24, 2000
Category: Informational
ENUM, E.164, and Internet Fax
Status of this Memo
This document is an Internet-Draft and is in full conformance with
all provisions of Section 10 of RFC2026 [1].
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF), its areas, and its working groups. Note that
other groups may also distribute working documents as Internet-
Drafts.
Internet-Drafts are draft documents valid for a maximum of six
months and may be updated, replaced, or obsoleted by other documents
at any time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."
The list of current Internet-Drafts can be accessed at
http://www.ietf.org/ietf/1id-abstracts.txt
The list of Internet-Draft Shadow Directories can be accessed at
http://www.ietf.org/shadow.html.
1. Abstract
E.164 numbers are often used for fax addresses. Internet fax
provides store-and-forward (T.37) and real-time (T.38) modes.
Subscribers could use ENUM to store Internet fax preferences in DNS
under their fax numbers. Network devices could then query DNS to
retrieve that information. An example is discovery of subscriber
preferences for receiving faxes via Internet mail, SIP delivery, or
H.323 delivery. Policy aspects are out of scope of this draft. This
document is not associated with any working group. Comments may be
sent to the author.
2. Conventions used in this document
This document includes very preliminary work. References to relevant
Internet RFCs and ITU-T Recommendations are provided.
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].
Gallant Expires May 2001 1
ENUM, E.164, and Internet Fax November 2000
3. ENUM and DNS
ENUM is described in RFC 2916 [3]. The response to a DNS query of
an E.164 number may contain multiple NAPTR records [4]. Each record
contains a URI, from which a service and address may be derived. An
example from RFC 2916 is the following:
- The original E.164 number is: +46-8-976-1234.
- The queried ENUM name is: 4.3.2.1.6.7.9.8.6.4.e164.arpa.
- The DNS response is:
$ORIGIN 4.3.2.1.6.7.9.8.6.4.e164.arpa.
IN NAPTR 100 10 "u" "sip+E2U" "!^.*$!sip:info@tele2.se!" .
IN NAPTR 102 10 "u" "mailto+E2U" "!^.*$!mailto:info@tele2.se!" .
This indicates that the subscriber prefers to be contacted first via
SIP and second via SMTP.
4. Internet Fax Operational Modes
General concepts for Internet fax may be found in RFC 2542 [5] and
Rec. F.185 [6]. References for store-and-forward Internet fax
include RFC 2305 [7], RFC 2532 [8] and Rec. T.37 [9]. A reference
for real-time Internet fax is Rec. T.38 [10]. Fax operational modes
are roughly as follows (see the references for further information):
- Store-and-forward fax using Internet mail (Rec. T.37):
- simple mode - supports transfer of image data.
- extended (full) mode - adds capabilities exchange, confirmation.
- Real-time (session oriented) fax over IP networks (Rec. T.38):
- preserves contents and sequence of messages, and
- maintains direct communications comparable to circuit-switched.
5. Possible URIs and NAPTRs for T.37 and T.38 faxes
URIs are described in RFC 2396 [11]. Email addressing for Internet
Fax is described in RFC 2304 [12] and RFC 2846 [13]. For SIP start
with RFC 2543 [14]. For telephony URLs see RFC 2806 [15]. For real-
time fax over H.323 see Rec. H.323 Annex D [16]. H.323 URL scheme
definition is in an Internet-Draft [17].
URIs may be used for service-specific handling. For T.37 and T.38
faxes, possible URIs based on example addresses might include:
- mailto:FAX=+46-8-976-1234@faxworld.org (store-and-forward, SMTP)
- sip:+46-8-976-1234@sipsco.com (real-time, SIP)
- h323:agallant-fax@newservices.com (real-time, H.323)
Gallant Expires May 2001 2
ENUM, E.164, and Internet Fax November 2000
Note that addresses of the form "userpart@hostpart" typically will
contain alias names [18] or may contain different telephone numbers.
NAPTRs (Naming Authority Pointer DNS resource records) are described
in RFC 2915. ENUM use of NAPTRs is described in RFC 2916. The usage
is roughly described as, "E.164 number in, URIs out." The NAPTR
fields for this include the service and regexp fields. The service
field may contain values for a protocol specification and a
resolution service. The regexp field (regular expression) shows how
to construct a name to use for the next step.
NAPTRs may be used for service-specific handling. For T.37 and T.38
faxes, possible values for the service field could include
T37fax+E2U and T38fax+E2U. This would indicate a particular fax
protocol and its association with a resolution service.
It is possible to imagine NAPTR records for store-and-forward and
real-time Internet fax that could look like the following:
IN NAPTR 100 10 "u" ( ; continue across line break
"T38fax+E2U" ; service field
"!^.*$!sip:+46-8-976-1234@sipsco.com!" ; regexp
. ) ; end of record
IN NAPTR 100 10 "u" ( ; continue across line break
"T38fax+E2U" ; service field
"!^.*$!h323:agallant-fax@newservices.com!" ; regexp
. ) ; end of record
IN NAPTR 102 10 "u" ( ; continue across line break
"T37fax+E2U" ; service field
"!^.*$!mailto:fax=+46-8-976-1234@faxworld.org!" ; regexp
. ) ; end of record
In this example, real-time fax is preferred over store-and-forward
fax, with SIP and H.323 delivery being equally preferred. Note that
T.38 records are given first by convention based on the values in
the order and preference fields.
6. ENUM and Internet Fax
A network device, such as an Internet fax gateway (onramp or
offramp) or an Internet Aware Fax (IAF) device, could use ENUM when
handling a fax addressed to an E.164 number.
In the example above, a DNS query returns information that the
subscriber prefers real-time delivery via either SIP or H.323 for
Internet faxes. The subscriber also has store-and-forward delivery
by SMTP as an available method.
Gallant Expires May 2001 3
ENUM, E.164, and Internet Fax November 2000
ENUM could be used to allow a subscriber to consolidate a variety of
delivery options. ENUM might also support Internet fax in a variety
of other ways.
Using NAPTRs provides flexibility for ENUM for Internet fax. The
example applies to delivery preference, service choice, and address
resolution, through the appropriate use of the order, service,
regexp, and other fields. Further work is indicated.
7. Formal Syntax
A possible goal of looking at ENUM for Internet fax is the
specification of NAPTRs and protocols for T.37 and T.38 faxes, for
delivery via Internet mail, SIP, and H.323.
Formal syntax may be developed as these and other possibilities are
identified and considered. Further work is indicated.
8. Security Considerations
Various RFCs and Internet drafts have already identified security
considerations for modes of Internet fax, Internet mail, SIP, and
ENUM. Further work is indicated to determine if different or
otherwise unforeseen security matters might occur.
9. 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.
3 RFC 2916, "E.164 number and DNS", P. Faltstrom, September 2000.
4 RFC 2915, "The Naming Authority Pointer (NAPTR) DNS Resource
Record", M. Mealling, R. Daniel, September 2000.
5 RFC 2542, "Terminology and Goals for Internet Fax", L. Masinter,
March 1999.
6 Rec. F.185, "Internet facsimile: Guidelines for the support of
the communication of facsimile documents", ITU-T, 06/98.
7 RFC 2305, "A Simple Mode of Facsimile Using Internet Mail", K.
Toyoda, H. Ohno, J. Murai, D. Wing, March 1998.
Gallant Expires May 2001 4
ENUM, E.164, and Internet Fax November 2000
8 RFC 2532, "Extended Facsimile Using Internet Mail", L. Masinter,
D. Wing, March 1999.
9 Rec. T.37, "Procedures for the transfer of facsimile data via
store-and-forward on the Internet", ITU-T, 06/98. Note also:
Rec. T.37 Amendment 1, "Full Mode", ITU-T, 09/99.
10 Rec T.38, "Procedures for real-time Group 3 facsimile
communication over IP networks", ITU-T, 06/98. Note also: Rec.
T.38 Amendment 1, ITU-T, 04/99; Rec. T.38 Amendment 2, ITU-T,
02/00 (to be published); Rec. T.38 Implementor's Guide, ITU-T,
06/00; and Rec. T.38 Draft Amendment 3 (to be approved).
11 RFC 2396, "Uniform Resource Identifiers (URI): Generic Syntax",
T. Berners-Lee, R. Fielding, L. Masinter, August 1998.
12 RFC 2304, "Minimal FAX address format in Internet Mail", C.
Allocchio, March 1998.
13 RFC 2846, "GSTN Address Element Extensions in E-mail Services",
C. Allocchio, June 2000.
14 RFC 2543, "SIP: Session Initiation Protocol. M. Handley, H.
Schulzrinne, E. Schooler, J. Rosenberg", March 1999.
15 RFC 2806, "URLs for Telephone Calls", A. Vaha-Sipila, April 2000.
16 Rec. H.323 ("Packet-Based Multimedia Communications Systems")
Annex D, "Real-time facsimile over H.323 systems", ITU-T, 11/00.
17 Internet Draft <draft-levin-iptel-h323-url-scheme-01.txt>, "H.323
URL scheme definition", O. Levin, November, 2000.
18 Private communication via email, O. Levin, 11/22/00.
10. Author's Address
Andrew Gallant
NeuStar, Inc.
1120 Vermont Ave NW Suite 550
Washington, DC 20005 USA
Phone: 202-533-2812
Fax: 202-533-2976
Email: andrew.gallant@neustar.com
Gallant Expires May 2001 5
ENUM, E.164, and Internet Fax November 2000
Full Copyright Statement
"Copyright (C) The Internet Society (2000). All Rights Reserved.
This document and translations of it may be copied and furnished to
others, and derivative works that comment on or otherwise explain it
or assist in its implementation may be prepared, copied, published
and distributed, in whole or in part, without restriction of any
kind, provided that the above copyright notice and this paragraph
are included on all such copies and derivative works. However, this
document itself may not be modified in any way, such as by removing
the copyright notice or references to the Internet Society or other
Internet organizations, except as needed for the purpose of
developing Internet standards in which case the procedures for
copyrights defined in the Internet Standards process must be
followed, or as required to translate it into languages other than
English.
The limited permissions granted above are perpetual and will not be
revoked by the Internet Society or its successors or assigns.
This document and the information contained herein is provided on an
"AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING
TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING
BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION
HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF
MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE."
Gallant Expires May 2001 6
