Network Working Group                                         G. Parsons
Request for Comments: 3362                               Nortel Networks
Category: Standards Track                                    August 2002


                Real-time Facsimile (T.38) - image/t38
                      MIME Sub-type Registration

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 (2002).  All Rights Reserved.

Abstract

   This document describes the registration of the MIME sub-type
   image/t38.  The encoding is defined by ITU Recommendation T.38 and is
   intended for use as an Session Description Protocol (SDP) media
   descriptor.

1.  Conventions used in this document

   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 BCP 14, RFC 2119
   [REQ].

2.  Overview

   This document describes the registration of the MIME sub-type
   image/t38.  The encoding is defined by [T.38] and is intended for use
   as an SDP media descriptor.

3.  T.38 Definition

   ITU-T Recommendation T.38 [T.38] describes the technical features
   necessary to transfer facsimile documents in real-time between two
   standard Group 3 facsimile terminals over the Internet or other
   networks using IP protocols.  The Recommendation allows the use of
   either TCP or UDP depending on the service environment.

   ITU-T Recommendation T.38 [T.38] Annex D describes system level
   requirements and procedures for internet aware facsimile
   implementations and internet aware facsimile gateways conforming to
   ITU-T T.38 to establish calls with other ITU-T T.38 implementations
   using the procedures defined in IETF RFC 2543 [SIP-99] and IETF RFC
   2327 [SDP].

   Note that ITU-T T.38 Recommendation T.38 (04/02) [T.38] is an
   aggregation of the original ITU-T Recommendation T.38 (06/98) [T.38-
   98] and all of the subsequent Amendments and Corrigendum including
   [T.38D-00].  While [T.38] and [T.38D-00] describe SIP procedures per
   [SIP-99], the procedures can also be applied to the revised Session
   Initiation Protocol specification [SIP].

3.1  image/t38 Usage

   Annex D of [T.38] describes that the image/t38 media type is intended
   to indicate a T.38 media stream in SDP.

   This media type registration is not intended for email usage.

4.  IANA Registration

      To: ietf-types@iana.org
      Subject: Registration of Standard MIME media type image/t38

      MIME media type name: image

      MIME subtype name: t38

      Required parameters: none

      Optional parameters: none

      Encoding considerations: Binary

      Security considerations:

         This content denotes a facsimile bit stream that may or
         may not be encrypted.

      Interoperability considerations :

         This MIME media subtype is intended to be used as a
         parameter by SDP in SIP call setup for T.38 as described in
         ITU-T Rec. T.38 Annex D.  Any use of this media type by
         email applications is not defined and as a result is not
         guaranteed to interoperate with a T.38 stream.

      Published specification:

         ITU-T Recommendation T.38, 'Procedures for real-time
         Group 3 facsimile communication over IP networks', April
         2002.

         A copy of the T.38 specifications can be found at:

         http://www.itu.int/rec/recommendation.asp?type=folders&
         lang=e&parent=T-REC-T.38

      Applications which use this media type:

         Real-time facsimile (fax)

      Additional information:

         Magic number(s):
              II (little-endian):
              MM (big-endian):
         File extension(s): .T38
         Macintosh File Type Code(s): T38

      Person & email address to contact for further information:

         Glenn W. Parsons
         gparsons@nortelnetworks.com

      Intended usage: COMMON

      Change controller: Glenn Parsons

5. Security Considerations

   Security considerations for this media type are discussed in the MIME
   type registration that appears in section 4.

6. References

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

   [MIME4]    Freed, N. and N. Borenstein, "Multipurpose Internet Mail
              Extensions (MIME) Part Four: Registration Procedures", BCP
              13, RFC 2048, November 1996.

   [SDP]      Handley, M. and V. Jacobson, "SDP: Session Description
              Protocol", RFC 2327, April 1998.

   [SIP]      Rosenberg, J., Schulzrinne, H., Camarillo, G., Johnston,
              A., Peterson, J., Sparks, R., Handley, M. and E. Schooler,
              "SIP: Session Initiation Protocol", RFC 3261, June 2002.

   [SIP-99]   Handley, M., Schulzrinne, H., Schooler, E. and J.
              Rosenberg, "SIP: Session Initiation Protocol", RFC 2543,
              March 1999.

   [T.38]     ITU-T Recommendation T.38, 'Procedures for real-time Group
              3 facsimile communication over IP networks', April 2002.

   [T.38-98]  ITU-T Recommendation T.38, 'Procedures for real-time Group
              3 facsimile communication over IP networks', June 1998.

   [T.38D-00] ITU-T Recommendation T.38 Amendment 2 Annex D, 'SIP/SDP
              Call Establishment Procedures', February 2000.

7. Authors' Address

   Glenn W. Parsons
   Nortel Networks
   P.O. Box 3511, Station C
   Ottawa, ON  K1Y 4H7
   Canada

   Phone: +1-613-763-7582
   Fax:   +1-613-763-2697
   EMail: gparsons@nortelnetworks.com

8. Full Copyright Statement

   Copyright (C) The Internet Society (2002).  All Rights Reserved.

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   the copyright notice or references to the Internet Society or other
   Internet organizations, except as needed for the purpose of
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   followed, or as required to translate it into languages other than
   English.

   The limited permissions granted above are perpetual and will not be
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   This document and the information contained herein is provided on an
   "AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING
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Acknowledgement

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