Applications Area Dan Wing Internet Draft Cisco Systems November 19, 1997 Expires May 1998 draft-ietf-fax-dsn-extensions-00.txt Extensions to Delivery Status Notifications for Fax Status of this memo This document is an Internet-Draft. 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." To learn the current status of any Internet-Draft, please check the "1id-abstracts.txt" listing contained in the Internet-Drafts Shadow Directories on ftp.is.co.za (Africa), ftp.nordu.net (Europe), munnari.oz.au (Pacific Rim), ds.internic.net (US East Coast), or ftp.isi.edu (US West Coast). Copyright Notice Copyright (C) The Internet Society (1997). All Rights Reserved. 1. Abstract This document describes new per-recipient Delivery Status Notification fields [DSN] useful for billing fax PSTN calls, and describes how to use existing Enhanced Mail System Status Codes [ENH-CODES] for fax, and describes new Enhanced Mail System Status Codes specifically for fax. 2. Introduction The fax specification [FAX-SPEC] describes the behavior of SMTP servers, fax onramps, and fax offramps. Wing Expires May 1998 [Page 1] Internet Draft DSN Extensions for Fax November 1997 [FAX-REQ] and [FAX-SCEN] should be consulted for detailed background information (XXX - text from [FAX-REQ, FAX-SCEN] should be included here). 2.1. Extensions to Delivery Status Notifications SMTP does not provide a mechanism to indicate the 'cost' associated with a message. Although a large message can cost more (network bandwidth, transmission time, disk storage, processing time to encode/ decode), there typically isn't a direct cost attributable to an email message. Fax messages are simply encoded as a MIME type [TIFF] and sent as normal email messages. However, a fax offramp functions as a gateway between SMTP and the PSTN. Costs are always associated with PSTN calls. These costs range from (at the lowest cost) a business telephone line itself with free local calls to (at the highest cost) a business telephone line making international telephone calls. These costs must be billed. It is desirable for users to audit the charges that are made to their bills, and a Delivery Status Notification that is sent to them (and possibly used by the billing system itself) provides a convenient method of verifying the accuracy of a bill. 2.2. Enhanced Mail System Status Codes While Enhanced Mail System Status Codes [ENH-CODES] is quite complete in its description of events specific to email, it does not provide error codes which map directly to all the error codes necessary for other services that are proposed to run over SMTP, such as VPIM [VPIM] or FPIM [FAX-SPEC]. This document describes how existing codes from [ENH-CODES] can be used with a fax offramp, and documents new codes that are necessary to support fax offramps. 2.3. Definitions This document uses several terms which aren't in common use. onramp: A device which receives an incoming fax call, translates the fax image to [TIFF], and can send the message to an SMTP server. An onramp can be diskless and have limited memory capacity. Wing Expires May 1998 [Page 2] Internet Draft DSN Extensions for Fax November 1997 offramp: A device which receives an SMTP message in [TIFF] format and calls a fax machine, translates the [TIFF] message to a fax image, and transmits the fax image to the remote fax machine. An offramp can be diskless and have limited memory capacity. PSTN: Public Switched Telephone Network. 2.4. Discussion of this Draft This draft is being discussed on the "ietf-fax" mailing list. To subscribe, send a message to: ietf-fax-request@imc.org with the line: subscribe in the body of the message. Archives are available from http://www.imc.org/ietf-fax. 3. New Per-recipient DSN Extension Codes Two new per-recipient extension fields, as described in [DSN], are defined using the format described in [ABNF]: extension-field = call-length / call-type call-length = "Call-Length" ":" call-seconds call-seconds = 1*DIGIT call-type = "Call-Type" ":" billing-rate billing-rate = "LD" / "local" / "international" / billing-ext billing-ext = "X-" vendorname "-" *ALPHA / *DIGIT vendorname = *ALPHA XXX - needs significantly more work 4. Enhanced Mail System Status Codes [ENH-CODES] allows new codes to be defined. The following table maps fax-specific codes to [ENH-CODES] codes where possible, and defines new fax-specific codes if [ENH-CODES] doesn't already have a suitable mapping. 4.1. Use of Existing Enhanced Mail System Status Codes by Fax Many of the codes described in [ENH-CODES] map perfectly to fax offramp failure and success codes. Wing Expires May 1998 [Page 3] Internet Draft DSN Extensions for Fax November 1997 XXX - do we want to overload these at all?? no such telephone number = 5.1.1 (Bad destination mailbox address) The mailbox specified in the address does not exist. For Internet mail names, this means the address portion to the left of the "@" sign is invalid. This code is only useful for permanent failures. unable to parse telephone number = 5.1.3 (Bad destination mailbox address syntax) The destination address was syntactically invalid. This can apply to any field in the address. This code is only useful for permanent failures. busy = X.4.1 (No answer from host) The outbound connection attempt was not answered, either because the remote system was busy, or otherwise unable to take a call. This is useful only as a persistent transient error. no answer = X.3.2 (System not accepting network messages) The host on which the mailbox is resident is not accepting messages. Examples of such conditions include an immanent shutdown, excessive load, or system maintenance. This is useful for both permanent and permanent transient errors. 4.2. New Enhanced Mail System Status Codes for Fax [ENH-CODES] describes that status codes have the following format: status-code = class "." subject "." detail class = "2"/"4"/"5" subject = 1*3digit detail = 1*3digit Fax-specific codes will have a subject of 8. XXX -- it would probably be better to more carefully specify these to correspond with the "subject"s that already exist (and define new detail codes) instead of a new "subject". X.8.X Fax Offramp Status The fax offramp status codes refer to events that are specific to a device dialing a remote phone number. The new fax-specific codes are: Wing Expires May 1998 [Page 4] Internet Draft DSN Extensions for Fax November 1997 no carrier = X.X.X XXX - description unable to train = X.X.X XXX - description no confirmation received from remote machine = X.X.X XXX - description 5. Security Considerations Security considerations are not (yet) described in this memo. 6. Acknowledgments XXX 7. References [ABNF] D. Crocker, P. Overell, "Augmented BNF for Syntax Specifications: ABNF", RFC 2234, November 1997. [DSN] K. Moore, "SMTP Service Extension for Delivery Status Notifications", RFC 1891, January 1996. [ENH-CODES] G. Vaudreuil, "Enhanced Mail System Status Codes", RFC 1893, January 1996. [FAX-REQ] L. Masinter, "Requirements for Internet FAX", Internet Draft, Work in Progress, draft-ietf-fax-requirements-XX.txt. [FAX-SCEN] D. Wing, "Scenarios for Delivery of FAX messages over SMTP", Internet Draft, Work in Progress, draft-ietf-fax- scenarios-XX.txt. [FAX-SPEC] L. Masinter, D.Wing, "Fax Profile for Internet Mail", Internet Draft, Work in Progress, draft-ietf-fax-spec-XX.txt [ITU-FAX] D. Crocker, "PROCEDURES FOR THE TRANSFER OF FACSIMILE DATA VIA INTERNET MAIL", Internet Draft, Work in Progress, draft- ietf-fax-itudc-XX.txt. [TIFF] L. McIntyre, S. Zilles, R. Buckley, D. Venable, "File Format for Internet Fax", Internet Draft, Work in Progress, draft- ietf-fax-tiffplus-XX.txt. Wing Expires May 1998 [Page 5] Internet Draft DSN Extensions for Fax November 1997 [VPIM] G. Vaudreuil, G. Parsons, "Voice Profile for Internet Mail - version 2", Internet Draft, Work in Progress, draft-ema-vpim- XX.txt. 9. Copyright Copyright (C) The Internet Society 1997. 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 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. 10. Author's Address Dan Wing Cisco Systems, Inc. 101 Cooper Street Santa Cruz, CA 95060 USA Phone: +1 408 457 5200 Fax: +1 408 457 5208 EMail: dwing@cisco.com Wing Expires May 1998 [Page 6]