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VPIM Working Group                                         Stuart McRae
Internet Draft                                        Lotus Development
Document: <draft-ietf-vpim-ivm-01.txt>                    Glenn Parsons
Category: Standards Track                               Nortel Networks
                                                      November 24, 2000

                         Internet Voice Messaging

Status of this Memo

   This document is an Internet-Draft and is in full conformance with
   all provisions of Section 10 of RFC2026.

   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
   The list of Internet-Draft Shadow Directories can be accessed at

1. Abstract

   This document provides for the carriage of voicemail messages over
   Internet mail as part of a unified messaging infrastructure.

   The Internet Voice Messaging (IVM) concept described in this
   document was originally called VPIM v3. This term has been dropped
   to reflect the fact that it is not a successor format to VPIM v2,
   but rather an alternative specification for a different application.

2. Conventions used in this document

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   this document are to be interpreted as described in RFC-2119

3. Introduction

   People naturally communicate using their voices, and this is
   preferable to typing for some forms of communication. By permitting
   voicemail to be implemented in an interoperable way on top of
   Internet Mail, voice messaging and electronic mail need no longer
   remain separate, isolated worlds and users will be able to choose
   the most appropriate form of communication. This will also enable

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   new types of device, without keyboards, to be used to participate in
   electronic messaging when mobile, in a hostile environment, or in
   spite of disabilities.

   There exist unified messaging systems which will transmit voicemail
   messages over the Internet using SMTP/MIME, but these systems suffer
   from a lack of interoperability because various aspects of such a
   message have not hitherto been standardized. In addition, voicemail
   systems can now conform to the Voice Profile for Internet Messaging
   (VPIM v2 as defined in RFC 2421 [VPIM2]) when forwarding messages to
   remote voicemail systems, but VPIM v2 was designed to allow two
   voicemail systems to exchange messages, not to allow a voicemail
   system to interoperate with a desktop e-mail client, and it is often
   not reasonable to expect a VPIM v2 message to be usable by an e-mail
   recipient. The result is messages which cannot be processed by the
   recipient (e.g., because of the encoding used), or look ugly to the

   This document therefore proposes a standard mechanism for
   representing a voicemail message within SMTP/MIME, and a standard
   encoding for the audio content, which unified messaging systems and
   mail clients MUST implement to ensure interoperability. By using a
   standard SMTP/MIME representation, and a widely implemented audio
   encoding, this will also permit most users of e-mail clients not
   specifically implementing the standard to still access the voicemail
   message. In addition, this document describes features an e-mail
   client SHOULD implement to allow recipient's to display voicemail
   message in a more friendly, context sensitive way to the user, and
   intelligently provide some of the additional functionality typically
   found in voicemail systems (such as responding with a voice message
   instead of e-mail). Finally is explained how a client MAY provide a
   level of interoperability with VPIM v2.

   It is desirable that unified messaging mail clients also be able to
   fully interoperate with voicemail servers. This is possible today,
   providing the client implements VPIM v2 [VPIMV2] in addition to this
   specification, and uses it to construct messages to be sent to a
   voicemail server. Separate work may be undertaken in the VPIM
   Working Group to provide further interoperability between clients
   implementing this specification and voicemail systems implementing

   This definition is based on the IVM goals document [GOALS], which is
   being revised to reflect subsequent discussions. This document is
   partly derived from VPIM v2 [VPIMV2] as well as ongoing discussion
   within the VPIM WG on IVM.  It references separate work on critical
   content [CRITICAL], content hints [HINT]. Addressing issues are
   discussed in a related Internet draft [ADDRESS]. Independent work
   within the IETF is also addressing VPIM directory issues.

   Further information on VPIM v2 and related activities can be found
   at http://www.vpim.org.

4. Message Format

   All messages MUST conform with the Internet Mail format as it is
   being defined by the DRUMS working group [DRUMSIMF].

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   The message header SHOULD indicate a content hint of "voice-message"
   (see [HINT]).

   If the receiving user agent identifies the message as a voice
   message (from the content hint), it MAY present it to the user as a
   voice message rather than as an electronic mail message with a voice

   Any content type is permitted in a message, but the top level
   content type on origination of a new, forwarded or reply voice
   message SHOULD be multipart/mixed. If the recipient is known to be
   VPIM v2 compliant then multipart/voice-message MAY be used instead
   (in which case all the provisions of [VPIMV2] SHOULD be

   If the message was created as a voice message, then the appropriate
   audio body part SHOULD be indicated as critical content, via a
   Content-Criticality parameter of CRITICAL (see [CRITICAL]).
   Additional important body parts (such as the original audio message
   if a voicemail is being forwarded) SHOULD also indicated via a
   Content-Criticality of CRITICAL. Contents which are not essential to
   communicating the meaning of the message (e.g. an associated vCard
   for the originator) MAY be indicated via a Content-Criticality of

   The top level content type on origination of a delivery notification
   message MUST be multipart/report. This will allow automatic
   processing of the delivery notification - for example, so that text-
   to-speech processing can render a non-delivery notification in the
   appropriate language for the recipient.

5. Transport

   The message MUST be transmitted in accordance with the Simple Mail
   Transport Protocol as it is being defined by the DRUMS working group

   Delivery Status Notifications SHOULD be requested [DSN] if delivery
   of the message is important to the originator.

6. Addressing

   Any valid Internet Mail address may be used for a voice message.

   It is desirable to be able to use and onramp/offramp for delivery of
   a voicemail message to a user, which will result in specific
   addressing requirements, based on service selectors as defined in
   [SELECTOR]. Further discussion of addressing requirements for voice
   messages can be found in the VPIM Addressing draft [ADDRESS].

   It is desirable to permit the use of a directory service to map
   between the E.164 phone number of the recipient and an SMTP mailbox
   address. How this might be achieved is currently under study in the
   VPIM and ENUM working groups [VPIMENUM],[SCHEMA].

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   If a message is created and stored as a result of call answering,
   the caller's name and number MAY be stored in the message headers in
   its original format per [CLID].

7. Notifications

   Delivery Status Notifications MUST be supported.  All non-delivery
   of messages MUST result in a NDN, if requested [DSN]. If the
   receiving system is unable to process all of the critical media
   types within a voice message (indicated by the content criticality),
   then it MUST non-deliver the entire message.

   Message Disposition Notifications SHOULD be supported (but according
   to MDN rules the user MUST be given the option of deciding whether
   MDNs are returned) [MDN].

   If the recipient is unable to display all of the indicated critical
   content components indicated, then it SHOULD give the user the
   option of returning an appropriate MDN (see [CRITICAL]).

8. Voice Contents

   Voice messages may be contained at any location within a message and
   MUST be contained in an audio/WAV content-type, unless the
   originator is aware that the recipient can handle other content.
   Specifically, Audio/32KADPCM MAY be used when the recipient is known
   to support VPIM v2 [VPIMV2].

   The VOICE parameter from VPIM v2 [VPIMV2] SHOULD be used to identify
   the any spoken names or spoken subjects (as distinct from voice
   message contents).

   The originator's spoken name SHOULD be included with messages as
   separate audio contents, if known, and indicated by the Content-
   Disposition as defined in VPIM v2 [VPIMV2]. If there is a single
   recipient for the message, their spoken name MAY also be included
   (per VPIM v2). A spoken subject MAY also be provided (per VPIM v2).

   An implementation MAY determine the recipient capabilities before
   sending a message and choose a codec accordingly (e.g. using some
   form of content negotiation).  In the absence of such recipient
   knowledge, implementations MUST use MS-GSM within the WAV file -
   indicated via "audio/wav; codec=31".

   Recipients MUST be able to play such a WAV encapsulated MS-GSM
   message, and MAY be able to play G.726 (indicated as audio/32kadpcm)
   to provide some interoperability with VPIM v2 [VPIMV2].

   An implementation MAY be able to play messages encoded with other
   codecs (either natively or via transcoding) but MUST be able to
   record WAV with MS-GSM.

   An implementation MAY support interoperability with VPIM v2
   [VPIMV2], in which case it MUST be able to record G.726 (indicated
   as audio/32kadpcm).

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   These requirements may be summarised as follows:

      Codec       No VPIM v2 Support     With VPIM V2 Support
                  Record    Playback     Record      Playback
      ------      ------    --------     ------      --------
      WAV/MS-GSM  MUST      MUST         MUST        MUST
      G.726       MAY       MAY          MUST        MUST
      Other       MAY       MAY          MAY         MAY

                 Editor's Note:  Based on ongoing discussions in the
                 VPIM WG, the baseline codec for IVM may be changed to
                 G.711 mu-law indicated via "audio/basic" or
                 "audio/wav; codec=7".

9. Fax Contents

   Fax contents SHOULD be carried according to RFC 2532 [IFAX].

10. Further Work

   The above text provides some guidelines as to how to ensure that a
   VPIM v2 message arriving on at a compliant mail system might be
   rendered useful to the recipient. However, a thorough investigation
   of interoperability with VPIM v2 is beyond the scope of this

   Other areas which are candidates to be referenced from this document
   include: Content Negotiation (inc. RESCAP); the VPIM Directory work;
   Spoken Header fields (embedded or references); the inclusion of
   additional voice message specific header information in the RFC822
   header; and a consideration of interoperability with e-mail clients
   not supporting this specification.

11. Security Considerations

   It is anticipated that there are no additional security issues
   beyond those identified in VPIM v2.

12. References

   [ADDRESS] Parsons, G., "VPIM Addressing", <draft-ietf-vpim-address-
   00.txt>, November 2000, Work in Progress.

   [CLID] Collins, J., "Calling Line Identification for VPIM Messages",
   <draft-ema-vpim-clid-01.txt>, November 2000, Work in Progress.

   [CRITICAL] Burger, E., Candell, E., "Critical Content of Internet
   Mail" <draft-burger-vpim-cc-02.txt>, November 2000, Work in

   [DSN] Moore, K., "SMTP Service Extension for Delivery Status
   Notifications" RFC 1891, January 1996.

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                       Internet Voice Messaging          November 2000

   [DRUMSMTP] Klensin, J., "Simple Mail Transfer Protocol", <draft-
   ietf-drums-smtpupd-13.txt>, Work in Progress.

   [DRUMSIMF] Resnick, P., "Internet Message Format", <draft-ietf-
   drums-msg-fmt-09.txt>, Work in Progress.

   [HINT]  Burger, E., Candell, E., Eliot, C., Klyne, G. "Message
   Context Internet Mail" <draft-ietf-vpim-hint-01.txt>, Novemebr 2000,
   Work in Progress.

   [IFAX] Masinter, L., Wing, D. "Extended Facsimile Using Internet
   Mail", RFC 2532, March 1999.

   [KEYWORDS] Bradner, S., "Key Words for use in RFCs To Indicate
   Requirement Levels", RFC 2119, March 1997.

   [GOALS] Candell, E., "Goals for Internet Voice MAil", <draft-ietf-
   vpim-ivm-goals-00.txt>, November 2000, Work in Progress.

   [MIME] Freed, N., Borenstein, N., "Multipurpose Internet Mail
   Extensions (MIME) Part One: Format of Internet Message Bodies", RFC
   2045, November 1996.

   [SELECTOR] Allocchio, C., "Minimal PSTN address format in Internet
   Mail", RFC 2303, March 1998.

   [VPIMENUM] Vaudreuil, G. "Voice Message Routing Service",<draft-
   ietf-vpim-routing-01.txt> , October 2000, Work in Progress.

   [SCHEMA] Brown, A., Vaudreuil, G. "Voice Messaging Directory
   Service",<draft-ietf-vpim-vpimdir-01.txt> , July 2000, Work in

   [VPIMV2]   Vaudreuil, G., Parsons, G., "Voice Profile for Internet
   Mail -  version 2", RFC 2421, September 1998.

   [VPIMV2R2]   Vaudreuil, G., Parsons, G., "Voice Profile for Internet
   Mail - version 2", <draft-ietf-vpim-vpimv2r2-01.txt>, November 2000,
   Work in Progress.

   [VPIMVM]   Vaudreuil, G., and Parsons, G., "VPIM Voice Message: MIME
   Sub-type Registration", RFC 2423, September 1998.

   [WAVMGSM]  Di Silvestro, L., Baribault, G., "Waveform Audio File
   Format MIME Sub-type Registration" <draft-ema-vpim-wav-00.txt>. Work
   in Progress.

13. Author's Addresses

   Stuart J. McRae
   Lotus Development
   43 Seymour Gardens
   Twickenham, United Kingdom
   TW1 3AR

   Phone: +44 208 891 1896
   Fax: +44 1784 499 112

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   Email: stuart_mcrae@lotus.com

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

   Phone: +1-613-763-7582
   Fax: +1-416-597-7005
   Email: gparsons@nortelnetworks.com

14. Full Copyright Statement

   Copyright (C) The Internet Society (2000).  All Rights Reserved.

   This document and translations of it may be copied and furnished to
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   or assist in its implementation may be prepared, copied, published
   and distributed, in whole or in part, without restriction of any
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   are included on all such copies and derivative works.  However, this
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   followed, or as required to translate it into languages other than

   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

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