Individual Submission A. Gallant Internet Draft NeuStar, Inc. Document: November 17, 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 subscriber preferences for receiving faxes via Internet mail or SIP delivery. Further work on ENUM for Internet Fax is indicated, one example being 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: - 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. See the references for further information. 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]. 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 - sip:+46-8-976-1234@sipsco.com Further work is indicated and could include H.323. Gallant Expires May 2001 2 ENUM, E.164, and Internet Fax November 2000 NAPTRs (Naming Authority Pointer DNS resource records) are described in RFC 2915. ENUM use of NAPTRs is decribed in RFC 2916. The usage is roughly described as, "E.164 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 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. Note that the T.38 record is given first by convention based on the values in the order and preference fields. Further work is indicated and could include H.323. 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 SIP for Internet faxes, but store-and-forward delivery by SMTP is also available. Further work is indicated and could include H.323. ENUM could allow a subscriber to consolidate a variety of delivery options. ENUM might also support Internet fax in a variety of 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. Gallant Expires May 2001 3 ENUM, E.164, and Internet Fax November 2000 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 and SIP (and possibly 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. 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. Gallant Expires May 2001 4 ENUM, E.164, and Internet Fax November 2000 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. 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 (date). 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 implmentation 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 Gallant Expires May 2001 6