Minimal FAX address format in Internet Mail
RFC 3192

Document Type RFC - Draft Standard (October 2001; No errata)
Obsoletes RFC 2304
Updates RFC 2846
Author Claudio Allocchio 
Last updated 2013-03-02
Stream IETF
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Network Working Group                                       C. Allocchio
Request for Comments: 3192                                    GARR-Italy
Obsoletes: 2304                                             October 2001
Updates: 2846
Category: Standards Track

              Minimal FAX address format in Internet Mail

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 (2001).  All Rights Reserved.


   This memo describes a simple method of encoding Global Switched
   Telephone Network (GSTN) addresses of facsimile devices in the
   local-part of Internet email addresses.

1. Introduction

   As with all Internet mail addresses, the left-hand-side (local-part)
   of an address generated according to this specification, is not to be
   interpreted except by the MTA that is named on the right-hand-side

   Since the very first e-mail to fax gateway objects appeared, a number
   of different methods to specify a fax address as an e-mail address
   have been used by implementors.  Several objectives for this methods
   have been identified, like to enable an e-mail user to send and
   receive faxes from his/her e-mail interface, to allow some kind of
   "fax over e-mail service" transport (possibly reducing the costs of
   GSTN long distance transmissions) while using the existing e-mail

   This memo describes the MINIMAL addressing method and standard
   extensions to encode FAX addresses into e-mail addresses, as required
   in reference [13].  The opposite problem, i.e., to allow a
   traditional numeric-only fax device user to access the e-mail
   transport service, is not discussed here.

Allocchio                   Standards Track                     [Page 1]
RFC 3192      Minimal FAX address format in Internet Mail   October 2001

   These IANA forms used to register the standard elements defined here
   are given in the "IANA Considerations" chapter (section 7 of this

   All implementations supporting FAX over e-mail address format MUST
   support this minimal specification.

1.1 Terminology and Syntax conventions

   In this document the formal definitions are described using ABNF
   syntax, as defined into [7].  We will also use some of the "CORE
   DEFINITIONS" defined in "APPENDIX A - CORE" of that document.  The
   exact meaning of the capitalized words


   is defined in reference [6].

   In this document the following new terms are also defined:

      I-fax device:
         an I-pstn device type [13] which is able to communicate either
         directly or indirectly with the traditional FAX over GSTN

         the Internet domain name which identifies uniquely an I-fax
         device over the Internet (see also mta-I-pstn in [13]);

         the complete Internet e-mail address structure which is used to
         transport a FAX address over the Internet e-mail service (see
         also pstn-email in [13]).

2. Minimal Fax address

   The minimal fax address within e-mail has been defined for
   consistency with reference [13] and it contains two elements: the
   fax-mbox and an optional qualif-type1 element.

   More precisely the GSTN minimal address specification requires the
   use of a unique service-selector for each specific application
   (section 2 in [13]).

   The "service-selector" defined for the fax service is as follows:

      service-selector = "FAX"

Allocchio                   Standards Track                     [Page 2]
RFC 3192      Minimal FAX address format in Internet Mail   October 2001

   In the syntax for the fax address a qualif-type1 element has been
   defined for support of T.30/T.33 subaddresses (see section 2 of
   [13]).  The use of this element is OPTIONAL, but compliant
   implementations MUST be able to support and correctly interpret it
   when present.  Its definition is as follows:

      qualif-type1 = "/" t33-sep "=" sub-addr


      t33-sep = "T33S"

      sub-addr = 1*( DIGIT )

   Thus, the minimal specification of a fax in e-mail address is:

      fax-address = fax-mbox [ "/T33S=" sub-addr ]

      fax-mbox = "FAX=" global-phone


      For the case of a single subaddress, only numbers are allowed in
      <sub-addr> which is consistent with T.30, T.33, and this document.
      While T.30 and T.33 use SPACE to pad its field, padding isn't
      necessary in the <sub-addr> field defined by this document.

      For the case of multiple subaddresses, T.33 specifies the "#"
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