VPIM Working Group Stuart McRae
Internet Draft Lotus Development
Document: <draft-ietf-vpim-ivm-02.txt> Glenn Parsons
Category: Standards Track Nortel Networks
July 19, 2001
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
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
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",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC-2119 [KEYWORDS].
McRae & Parsons Expires: 19/02/02 1
Internet Voice Messaging July 2001
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 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] and being clarified for Draft
Standard in [VPIMV2R2]) 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 user.
This document therefore proposes a new 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.
The definition in this document is based on the IVM Requirements
document [GOALS]. It references separate work on critical content
[CRITICAL] and message context [HINT]. Addressing and directory issues
are discussed in related documents [ADDRESS], [VPIMENUM], [SCHEMA].
McRae & Parsons Expires: 19/02/01 2
Internet Voice Messaging July 2001
Further information on VPIM and related activities can be found at
http://www.vpim.org or http://www.ema.org/vpim.
4. Message Format
Voice messages may be created explicitly by a user (e.g. recording a
voicemail message in their mail client) or implicitly by a unified
messaging system (when it records a telephone message).
All messages MUST conform with the Internet Mail format, as updated by
the DRUMS working group [DRUMSIMF].
The message header SHOULD indicate a message context of "voice-message"
(see [HINT]).
If the receiving user agent identifies the message as a voice message
(from the message context), it MAY present it to the user as a voice
message rather than as an electronic mail message with a voice
attachment (see [BEHAVIOUR]).
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 [VPIMV2R2] MUST be implemented in constructing the
message).
If the message was created as a voice message, then the appropriate
audio body part SHOULD be indicated as critical content, via a
Criticality parameter of CRITICAL on the Content-Disposition (see
[CRITICAL]). Additional important body parts (such as the original
audio message if a voicemail is being forwarded) SHOULD also indicated
via a 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 Criticality of IGNORE.
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 updated by the DRUMS working group [DRUMSMTP].
McRae & Parsons Expires: 19/02/01 3
Internet Voice Messaging July 2001
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 document [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. A
discussion on how this may be achieved using the ENUM infrastructure is
in [VPIMENUM]. A definition of the VPIM LDAP schema that a system
would use is found in [SCHEMA].
If a message is created and stored as a result of call answering, the
callerÆs 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 per [CRITICAL].
Message Disposition Notifications SHOULD be supported (but according to
MDN rules the user MUST be given the option of deciding whether MDNs
are returned) per [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
SHOULD always be contained in either an audio/wav or audio/basic
content-type. The only exception is when the originator is aware that
McRae & Parsons Expires: 19/02/01 4
Internet Voice Messaging July 2001
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 on Content-Disposition 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 VOICE parameter 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).
A sending 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, sending implementations MUST use either: MS-GSM with a WAV
header - indicated via "audio/wav; codec=31" [MSGSM],[WAV]; or raw
G.711 mu-law - - indicated via "audio/basic" [G711],[MIME2]. A sending
implementation MAY support interoperability with VPIM v2 [VPIMV2], in
which case it MUST be able to record G.726 (indicated as
audio/32kadpcm)[G726],[ADPCM].
Recipients MUST be able to play both a WAV encapsulated MS-GSM and a
raw G.711 mu-law message, and MAY be able to play G.726 (indicated as
audio/32kadpcm) to provide interoperability with VPIM v2. A receiving
implementation MAY also be able to play messages encoded with other
codecs (either natively or via transcoding).
These requirements may be summarized as follows:
Codec No VPIM v2 Support With VPIM V2 Support
Record Playback Record Playback
------------- ------ -------- ------ --------
MS-GSM in WAV MAY* MUST MAY* MUST
G.711 mu-law MAY* MUST MAY* MUST
G.726 MAY MAY MUST MUST
Other MAY MAY MAY MAY
*MUST record at least one
9. Fax Contents
Fax contents SHOULD be carried according to RFC 2532 [IFAX].
10. Interoperability with VPIM v2
McRae & Parsons Expires: 19/02/01 5
Internet Voice Messaging July 2001
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 how full
interoperability might be provided between IVM and VPIM v2 systems is
beyond the scope of this document.
11. Security Considerations
It is anticipated that there are no additional security issues beyond
those identified in VPIM v2 [VPIMV2R2].
McRae & Parsons Expires: 19/02/01 6
Internet Voice Messaging July 2001
12. References
[ADDRESS] Parsons, G., "VPIM Addressing", <draft-ietf-vpim-address-
01.txt>, April 2001, Work in Progress.
[ADPCM] G. Vaudreuil and G. Parsons, "Toll Quality Voice - 32 kbit/s
ADPCM: MIME Sub-type Registration", RFC 2422, September 1998. Revised
by: <draft-ietf-vpim-vpimv2r2-32k-01.txt>, June 2001.
[BEHAVIOUR] Parsons, G., Maruszak, J., "Voice Messaging Client
Behaviour", <draft-ema-vpim-cb-02.txt>, July 2001, Work in Progress.
[CLID] Parsons, G., Maruszak, J., "Calling Line Identification for VPIM
Messages", <draft-ema-vpim-clid-02.txt>, June 2001, Work in Progress.
[CRITICAL] Burger, E., Candell, E., "Critical Content of Internet Mail"
<draft-burger-vpim-cc-04.txt>, April 2001, Work in Progress.
[DSN] Moore, K., "SMTP Service Extension for Delivery Status
Notifications" RFC 1891, January 1996.
[DRUMSMTP] Klensin, J., "Simple Mail Transfer Protocol", RFC 2821 ,
April 2001.
[DRUMSIMF] Resnick, P., "Internet Message Format", RFC 2822, April
2001.
[GOALS] Candell, E., "Goals for Internet Voice Mail", <draft-ietf-vpim-
ivm-goals-03.txt>, April 2001, Work in Progress.
[G726] CCITT Recommendation G.726 (1990), General Aspects of Digital
Transmission Systems, Terminal Equipment - 40, 32, 24, 16 kbit/s
Adaptive Differential Pulse Code Modulation (ADPCM).
[G711] ITU-T Recommendation G.711 (1993), General Aspects of Digital
Transmission Systems, Terminal Equipment - Pulse Code Modulation (PCM)
of Voice Frequencies.
[HINT] Burger, E., Candell, E., Eliot, C., Klyne, G. "Message Context
Internet Mail" <draft-ietf-vpim-hint-07.txt>, June 2001, 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.
[MIME1] Freed, N., Borenstein, N., "Multipurpose Internet Mail
Extensions (MIME) Part One: Format of Internet Message Bodies", RFC
2045, November 1996.
McRae & Parsons Expires: 19/02/01 7
Internet Voice Messaging July 2001
[MIME2] N. Freed and N. Borenstein, "Multipurpose Internet Mail
Extensions (MIME) Part Two: Media Types ", RFC 2046, Innosoft, First
Virtual, November 1996.
[MSGSM] Di Silvestro, L., Hedberg, E., Baribault, G., "Microsoft GSM
MIME Sub-type Registration" <draft-ema-vpim-wav-00.txt>, April 1999,
Work in Progress (expired).
[SELECTOR] Allocchio, C., "Minimal PSTN address format in Internet
Mail", RFC 2303, March 1998.
[SCHEMA] Brown, A., Vaudreuil, G. "Voice Messaging Directory
Service",<draft-ietf-vpim-vpimdir-01.txt> , July 2000, Work in Progress
(expired).
[VPIMENUM] Vaudreuil, G. "Voice Message Routing Service", <draft-ietf-
vpim-routing-01.txt> , July 2000, Work in Progress (expired).
[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-vpimv2r2-03.txt>, June 2001, Work
in Progress.
[WAV] Di Silvestro, L., Baribault, G., "Waveform Audio File Format
MIME Sub-type Registration" <draft-ema-vpim-wav-00.txt>, April 1999,
Work in Progress (expired).
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
Email: stuart_mcrae@lotus.com
Glenn W. Parsons
Nortel Networks
P.O. Box 3511, Station C
Ottawa, ON K1Y 4H7
Canada
McRae & Parsons Expires: 19/02/01 8
Internet Voice Messaging July 2001
Phone: +1-613-763-7582
Fax: +1-416-597-7005
Email: gparsons@nortelnetworks.com
McRae & Parsons Expires: 19/02/01 9
Internet Voice Messaging July 2001
14. Full Copyright Statement
Copyright (C) The Internet Society (2001). 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 implementation 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.
McRae & Parsons Expires: 19/02/01 10
Datatracker
draft-ietf-vpim-ivm-02
Internet-Draft
