[Search] [pdfized|bibtex] [Tracker] [WG] [Email] [Diff1] [Diff2] [Nits]
Versions: 00 01 02 rfc4024                                 Informational
     Network Working Group                              Janusz Maruszak
     Internet Draft                                     Nortel Networks
     Document: <draft-ema-vpim-cb-02.txt>                 Glenn Parsons
     Category: Informational                            Nortel Networks
                                                          July 18, 2001

                          Voice Messaging Client Behaviour

     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

Maruszak & Parsons         Expires:  18/01/02                        1

                   Voice Messaging Client Behaviour      July 18, 2001

     Table of Contents

     1. Abstract.....................................................3
     2. Conventions used in this document............................3
     3. Introduction.................................................3
     4. Message Icon.................................................4
     4.1 Proposed Mechanism..........................................4
     5. Sender's Number Column.......................................4
     5.1 Proposed Mechanism..........................................4
     6. Message Size.................................................5
     6.1 Proposed Mechanism..........................................5
     7. Media Viewer.................................................6
     7.1 Proposed Mechanism..........................................7
     8. Mark Message as Read.........................................7
     8.1 Proposed Mechanism..........................................7
     9. Security Considerations......................................7
     10. References..................................................8
     11. Acknowledgments.............................................8
     12. Author's Addresses..........................................8
     13. Full Copyright Statement....................................9

Maruszak & Parsons         Expires: 24/05/01                         2

                   Voice Messaging Client Behaviour      July 18, 2001

     1. Abstract

     This document defines the expected behaviour of a client to   various
     aspects of a VPIM message or any voice and/or fax message.

     2. Conventions used in this document

     In examples, "C:" and "S:" indicate lines sent by the client and server

     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 [4].

     3. Introduction

     As Internet messaging evolves into unified messaging, the term "e-mail" no
     longer refers to text-only messages.  Today's "e-mail" are often multi-
     media.  That is, they can have numerous non-text parts. These parts can be
     attachments or can contain voice and/or fax.

     Each of voice, fax, and text have their own distinct characteristics, which
     are intuitive to the user.  For example, each of these message types
     require a different media viewer (text editor for text, audio player for
     voice, and image viewer for fax), and the dimensions of message size are
     also different for all three (kilobytes for text, seconds for voice, and
     pages for fax).  As a result, a message that includes more than one of
     these in its parts is termed a mixed media message.

     How the messaging client responds to, and acts on these differences is
     termed "Client Behaviour".  This is dependant on the concept of "Message-
     Context" [2] (previously called primary content), which defines whether the
     message is a voice mail, fax, or text message.  The client can utilize this
     header to determine the appropriate client behaviour for a particular

     Traditionally, a messaging "client" referred to some sort of visual
     interface (or GUI -
graphical user interface) that was presented on the
     users computer.  However, as messaging evolves to unified communications
     the actual form of the messaging client is expected to change.  TodayËs
     email can often be viewed on wireless devices with very limited screens or
     even "viewed" over a telephone (i.e., listening to email as you would
     listen to voice mail through a TUI -
telset user interface).

     The intent of this document is to be general and refer to all types of
     messaging clients, as the userËs expectation of behaviour based on the
     type of message is not expected to change.  However, some of the following
     concepts may tend towards the more common GUI client.

Maruszak & Parsons        Expires: 24/05/01                         3

                   Voice Messaging Client Behaviour      July 18, 2001

     4. Message Icon

     The preferred method to distinguish between voice, fax, and text messages
     on a GUI client is with a visual cue, or icon.  A similar voice prompt or
     "earcon" would be used for TUI clients.

     As it is possible for the message to contain more than one media type, the
     icon should describe the primary message content, as defined by the
     "Message-Context" header.  Obvious choices for the icon/message pairs would
     be a telephone for a voice message, a fax machine for a fax message, and an
     envelope for a text mail message.  Similarly obvious for the earcons would
     be short spoken prompts like "voice message".

     This could be taken a step further, and have the GUI icon change to
     indicate that the message has been read as is currently done in some email
     clients (others do not change the icon but merely bold the message in the
     message list to indicate it is unread).  For example, a telephone with the
     receiver off-hook could indicate that the voice message has been played.  A
     fax machine with paper at the bottom, as opposed to the top, would show
     that the fax had been viewed.  Finally, an open envelope indicates that a
     text message has been read.

     4.1 Proposed Mechanism

     As the choice of icon is determined by the primary message type, the client
     should obtain this information from the "Message-Context " message header.
     This header is defined in [2].

     5. Sender's Number Column

     As is the case with most email GUI clients today, important message
     information is organized into columns when presented to the user in a the
     summary message list. TUIs often present even briefer aummaries to the user
     at the beginning of the session.  Typical columns in the GUI client include
     the message subject, and the date the message was received.

     Another important piece of information for the user is the origin of the
     message.  For a voice or fax message, the origin is typically a telephone
     or fax machine respectively, each of which has an associated telephone
     number.  This telephone number is critical to the user if they wish to
     return the call.  This should be presented accurately to the user (without
     making it an email address).

     5.1 Proposed Mechanism

     Instead of forcing the telephone number into an email address, a new
     Internet message header can be used to hold the originating telephone
     number [3].  If the message is indicated as being a voice or fax message
     per [2], the client should extract the number, and display it to the user

Maruszak & Parsons        Expires: 24/05/01                         4

                   Voice Messaging Client Behaviour      July 18, 2001

     in a separate column.  As this header is defined to only hold the digits of
     the telephone number, it is left to the client to add any separating
     characters (e.g. "-").

     6. Message Size

     In the cases of large attachments, small clients (e.g., PDA) and slow links
     (e.g., wireless) there is also a need for the client to see the length of
     the message in a suitable format before opening it.

     Currently, message size is normally given in kilobytes (kB).  This  is
     sufficient for plain text messages, but while it may give a hint as to how
     good the compression algorithm is, kB is not very useful in knowing the
     size of a voice and/or fax message.  Instead, the size should give an
     indication of the length of the message, i.e. the duration (in seconds) of
     a voice message, and the number of pages of a fax.  Again, the message may
     contain multiple types, so the size displayed should be that of the primary
     content type, per [2].

     6.1 Proposed Mechanisms

     There are three suggested methods to relay this information, of them, the
     first method is favoured:

     6.1.1  MIME Header Content-Duration as described in RFC 2424 [5]

     For voice messages, the Content-Duration field of the main audio/* body
     part (as indicated by content-disposition per [1]) should be displayed as
     the length of the message.  If there are several audio parts, an
     implementation may display the message size as an aggregate of the length
     of each.

     For fax messages a new MIME Header, Content-Page-Length, could be defined,
     similar to Content-Duration with the exception that number of pages would
     be specified, rather than number of seconds. (e.g. Content-Page-Length:3).
     This would be created at origination.

     6.1.2  Message length indicated as a parameter of an existing Content-Type
     Header Field

     This would be created at the source.  This proposed method would allow the
     message length to be passed to the client by default in IMAP.  Again the
     client would have to choose between the main voice message length or an
     aggregate message length for display.

Maruszak & Parsons        Expires: 24/05/01                         5

                   Voice Messaging Client Behaviour      July 18, 2001

     Content-Type Header Field example:

     Content-Type=audio/*; length=50
     Content-Type=image/tiff; pages=3

     6.1.3  Message length indicated as part of an existing RFC822 [9] Header

     This field would be created at the source and may include message length
     information, but because it is part of the message headers, it could also
     be amended on reception (by a local process).  This method would allow the
     message length to be passed to any client by default and not require any
     client modification.  If used, this field would indicate the aggregate
     length of all attachments.

     The advantage of this mechanism is that no new headers are required and it
     works with existing clients.  The downside is that it overloads the subject

     Subject Header Field example:

     Subject=Voice Message (0:04)
     Subject=Fax Message (3p)
     Subject=Voice Message (0:14) with Fax (1p)

     7. Media Viewer

     When a message is initially opened, the client should, by default, open
     the proper media viewer to display the primary message content.  That is,
     an audio player for voice messages, an image viewer for fax, and a text
     editor for text messages.  Note that on a TUI, the viewer would render the
     media to sound (which would have varying effect depending on the media and
     available process).

     Where there is more than one body part, obviously the appropriate viewer
     should be used depending on which body part the user has selected.

     In the case where several viewers are available for a single media type,
     the user should be prompted to select the desired viewer on the first
     occasion that the message type is encountered.  That viewer should then
     become the default viewer for that media type.  The user should have the
     ability to change the default viewer for a media type at any time.

     Note that it is possible that the media viewer may not be part of the
     client or local to the host of the client.  For example, a user could
     select to play a voice message from a GUI and the message is played over a
     telephone (perhaps because the user has no desktop speakers).
     Additionally, a user listening to a unified messaging inbox over a TUI
     could chose to print a particular message to a nearby fax machine.

Maruszak & Parsons        Expires: 24/05/01                         6

                   Voice Messaging Client Behaviour      July 18, 2001

     7.1 Proposed Mechanism

     As mentioned, the default viewer displayed to the user should be the
     appropriate one for the primary message type.  The client is able to
     determine the primary message type from the "Message-Context" message
     header per [2].

     8. Mark Message as Read

     Obviously, the user must be able to know which messages they have read, and
     which are unread.  This feature would also control the message icon or
     earcon as mentioned in section 1.

     With the proliferation of voice and fax messages, clients should only
     indicate that these messages are read when the primary body part has been
     read. For example, a voice message should not be indicated as read until
     the audio part has been played.  The default is currently to mark a message
     read, when the first body part (typically text) is viewed.

     8.1 Proposed Mechanism

     Implementation of this feature on most clients is a local issue.

     For example, in the case of IMAP4 [6], these clients should only set the
     \SEEN flag after the first attachment of the primary content type has been
     opened.  That is, if the message context is voice message, the \SEEN flag
     would be set after the primary voice message (indicated by content-
     disposition [1] or content-criticality [8]) is opened.

     9. Security Considerations

     The desirable client behaviours described here are intended to provide the
     user with a better client experience.  However, supporting the proposed
     behaviours described in this document does not make a client immune from
     the risks of being a mail client.  That is, the client is not responsible
     for the format of the message received, it only interprets.  As a result,
     messages could be spoofed or masqueraded to look like a message they are
     not to elicit a desired client behaviour.  This could be used to fool the
     end user, for example, into thinking a message was a voice message
     (because of the icon) when it was not.

Maruszak & Parsons        Expires: 24/05/01                         7

                   Voice Messaging Client Behaviour      July 18, 2001

     10. References

     1. Parsons, G., Vaudreuil, G., "Voice Profile for Internet Mail -  version
     2", draft-ietf-vpim-vpimv2r2-03.txt, June 2001, Work in Progress.

     2. Burger, E., Candell, E., Klyne, G., Eliot, C., "Message Context for
     Internet Mail", draft-ietf-vpim-hint-07.txt, June 2001, Work in Progress

     3. Parsons & Maruszak, "Calling Line Identification for VPIM Messages",
     draft-ema-vpim-clid-02.txt, June 2001, Work in Progress

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

     5. Vaudreuil, G., Parsons, G., "Content Duration MIME Header Definition",
     RFC2424, September 1998

     6. Crispin, M., "Internet Message Access Protocol - Version 4rev1", RFC
     2060, December 1996

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

     8. Burger, E., "Critical Content of Internet Mail" <draft-burger-vpim-cc-
     04.txt>, June 2001, Work in Progress.

     9. Resnick, P., "Internet Message Format", RFC 2822, April 2001.

     11. Acknowledgments

     This work was inspired by the discussion of "Proposed Mechanisms" for IMAP
     that were detailed in a since expired draft (draft-ema-vpim-imap-01.txt).
     The authors would like to acknowledge all those who contributed to that
     document.  In addition, Cheryl Kinden, Derrick Dunne and Jason Maruszak
     assisted in the editing of previous revisions of this document.

     12. Author's Addresses

     Janusz Maruszak
     Nortel Networks
     522 University Avenue
     Toronto, ON  M5G 1W7

     Phone: +1-416-597-7517
     Email: marusj@nortelnetworks.com

Maruszak & Parsons        Expires: 24/05/01                         8

                   Voice Messaging Client Behaviour      July 18, 2001

     Glenn 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

     13. 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

Maruszak & Parsons        Expires: 24/05/01                         9