VPIM Voice Message MIME Sub-type Registration
A MIME label to mark messages as voice mail.
Vaudreuil, G. and G. Parsons, "VPIM Voice Message MIME Sub-type Registration", RFC 2423, DOI 10.17487/RFC2423, September 1998, <https://www.rfc-editor.org/info/rfc2423>.
@misc{rfc2423,
series = {Request for Comments},
number = 2423,
howpublished = {RFC 2423},
publisher = {RFC Editor},
doi = {10.17487/RFC2423},
url = {https://www.rfc-editor.org/info/rfc2423},
author = {G. Vaudreuil and G. Parsons},
title = {{VPIM Voice Message MIME Sub-type Registration}},
pagetotal = 6,
year = 1998,
month = sep,
} RFC text
Contents
Network Working Group G. Vaudreuil
Request for Comments: 2423 Lucent Technologies
Obsoletes: 1911 G. Parsons
Category: Standards Track Northern Telecom
September 1998
VPIM Voice Message
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 (1998). All Rights Reserved.
Overview
This document describes the registration of the MIME sub-type
multipart/voice-message for use with the Voice Profile for Internet
Mail (VPIM). A full description of usage can be found in the VPIM v2
specification.
1. Abstract
This document describes the registration of the MIME sub-type
multipart/voice-message for use with the Voice Profile for Internet
Mail (VPIM). A full description of usage can be found in the VPIM v2
specification [VPIM2]. This document revises an earlier sub-type
registration in RFC 1911 [VPIM1].
2. VPIM Scope
The VPIM specification defines a restricted profile of the Internet
multimedia messaging protocols for use between voice processing
platforms. These platforms have historically been special-purpose
computers and often do not have the same facilities normally
associated with a traditional Internet Email-capable computer. As a
result, VPIM also specifies additional functionality as it is needed.
The profile is intended to specify the minimum common set of features
to allow interworking between compliant systems.
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 [REQ].
3. Voice Message Interchange
3.1 multipart/voice-message
The MIME sub-type multipart/voice-message is defined to hold specific
media contents that are interchanged in messages between voice
messaging systems described in [VPIM2]. Essentially, the sub-type
provides a simple wrapper that easily identifies the entire content
as being the components of a single voice message. The sub-type is
identical in semantics and syntax to multipart/mixed, as defined in
[MIME2]. As such, it may be safely interpreted as a multipart/mixed
by systems that do not understand the sub-type (only the
identification as a voice message would be lost).
This mechanism allows the insertion of an explanatory preamble (e.g.
VPIM voice message attached) for recipients who read the message with
pre-MIME software, since the preamble will be ignored by MIME-
compliant software.
In addition to the MIME required boundary parameter, a version
parameter is also required for this sub-type. This is to
distinguish, this refinement of the sub-type from the previous
definition in [VPIM1]. The value of the version parameter is "2.0"
if the content conforms to the requirements of [VPIM2]. Should there
be further revisions of this content type, there MUST be backwards
compatibility (i.e. systems implementing version n can read version
2, and systems implementing version 2 can read version 2 contents
within a version n). The default version value (when the parameter
is missing) is 1, indicating the content conforms to the requirements
of [VPIM1].
[VPIM2] describes the restriction that only specific media types,
applicable to voice messaging, are valid `next-level' contents of
this sub-type (when version=2.0). They are: audio/*, image/*,
message/rfc822 and application/directory. The multipart provides for
the packaging of as many of these contents as is necessary.
3.2 VPIM v2 Usage
The multipart/voice-message sub-type is a primary component of the
VPIM specification [VPIM2]. All VPIM Messages MUST contain this
sub-type to identify the wrapping of a voice message. The contents
of this wrapper can vary from only one audio/32KADPCM content to a
complex set of related and nested contents.
Typically, if more than one audio segment is present, the first is
the spoken name of the originator, the second is the spoken subject,
and the third is the voice message itself. This order, however, MUST
NOT be assumed in any case. Further, the order that the contents
appear SHOULD be the order in which they are presented to the user.
The spoken name segment, if available, shall contain the name of the
message sender in the voice of the sender. The length of the spoken
name segment must not exceed 12 seconds.
The spoken subject segment, if available, shall contain the subject
of the message sender in the voice of the sender. The length of the
spoken subject segment must not exceed 20 seconds.
The directory information part, if present, will contain information
specific to the orginator of the voice message.
Refer to the VPIM v2 Specification for details on proper usage.
4. IANA Registration
To: ietf-types@iana.org
Subject: Registration of MIME media type
multipart/voice-message
MIME media type name: multipart
MIME subtype name: voice-message
Required parameters: boundary, version
The use of boundary is defined in [MIME2]
The version parameter that contains the value "2.0" if
enclosed content conforms to [VPIM2]. The absence of this
parameter indicates conformance to the previous version
defined in RFC 1911 [VPIM1].
Optional parameters: none
Encoding considerations: 7bit, 8bit or Binary
Security considerations:
This definition identifies the content as being a voice
message. In some environments (though likely not the
majority), the loss of the anonymity of the content may be a
security issue.
Interoperability considerations:
Systems developed to conform with [VPIM1] may not conform to
this registration. Specifically, the required version will
likely be absent, in this case the recipient system should
still be able to accept the message and will be able to
handle the content. The VPIM v1 positional identification,
however, would likely be lost.
Published specification:
This document
[VPIM2]
Applications which use this media type:
Primarily voice messaging
Additional information:
Magic number(s): ?
File extension(s): .VPM
Macintosh File Type Code(s): VPIM
Person & email address to contact for further information:
Glenn W. Parsons
Glenn.Parsons@Nortel.ca
Gregory M. Vaudreuil
Greg.Vaudreuil@Octel.Com
Intended usage: COMMON
Author/Change controller:
Glenn W. Parsons & Gregory M. Vaudreuil
5. Authors' Addresses
Glenn W. Parsons
Northern Telecom
P.O. Box 3511, Station C
Ottawa, ON K1Y 4H7
Canada
Phone: +1-613-763-7582
Fax: +1-613-763-4461
EMail: Glenn.Parsons@Nortel.ca
Gregory M. Vaudreuil
Lucent Technologies
17080 Dallas Parkway
Dallas, TX 75248-1905
United States
Phone/Fax: +1-972-733-2722
EMail: GregV@Lucent.Com
6. References
[MIME2] Freed, N., and N. Borenstein, "Multipurpose Internet Mail
Extensions (MIME) Part Two: Media Types ", RFC 2046, November
1996.
[MIME4] Freed, N., Klensin, J., and J. Postel, "Multipurpose Internet
Mail Extensions (MIME) Part Four: Registration Procedures",
RFC 2048, November 1996.
[VPIM1] Vaudreuil, G., "Voice Profile for Internet Mail", RFC 1911,
February 1996.
[VPIM2] Vaudreuil, G., and G. Parsons, "Voice Profile for Internet
Mail - version 2", RFC 2421, September 1998.
[REQ] Bradner, S., "Key words for use in RFCs to Indicate Requirement
Levels", BCP 14, RFC 2119, March 1997.
7. Full Copyright Statement
Copyright (C) The Internet Society (1998). 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 implmentation 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
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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
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."
AI ELI5
On this page
§1Why Voice Mail Needs a Label
The Voice Profile for Internet Mail (VPIM) brings voice messaging to email systems. A voice message is not plain text or a simple attachment—it is a structured package that may contain multiple parts: the sender's spoken name, the message subject, the voice content itself, and directory information about the sender. Email systems need a way to recognize and handle these packages correctly.
RFC 2423 defines multipart/voice-message, a MIME subtype specifically designed as a container for VPIM voice messages. This label tells email clients and systems that they are dealing with voice mail, so they can process it appropriately.
A voice message has several pieces: who it is from (their voice), what it is about, and what they are saying. The email label multipart/voice-message wraps all these pieces together so the email system knows what to do with them.
§2The multipart/voice-message Container
The multipart/voice-message subtype is functionally identical to multipart/mixed, defined in RFC 2046. This means systems that do not recognize multipart/voice-message can safely treat it as a regular mixed container without breaking the message. The difference is semantic: the presence of multipart/voice-message signals that the contents represent a voice message.
A multipart/voice-message container must include two required parameters: boundary (which separates the message parts) and version (which indicates conformance to VPIM version 2.0 or earlier). The version parameter allows future versions of VPIM to maintain backward compatibility.
Think of multipart/voice-message as a labeled box. Inside the box are the voice recording, the sender's name, and other pieces. The label tells a mail program what kind of box it is.
§3What Goes Inside
A VPIM v2 voice message typically contains multiple parts in this order: a spoken name segment (the sender's voice saying their name), a spoken subject segment (the sender's voice stating the topic), and the voice message itself. Additional parts may include images and directory information about the message sender.
The spoken name must not exceed 12 seconds; the spoken subject must not exceed 20 seconds. Only specific media types are allowed inside a v2 container: audio/*, image/*, message/rfc822 and application/directory. This restriction ensures that VPIM systems can reliably process voice messages.
A voice message typically has three parts: first, the sender says their name (up to 12 seconds), next they state the subject (up to 20 seconds), then comes the message itself. There may also be a picture or contact information.
§4Identifying Voice Messages
RFC 2423 acknowledges a privacy consideration: the multipart/voice-message label explicitly identifies a message as voice mail. In some environments where message content confidentiality is important, this visible labeling could reveal information about message types. However, in most practical email deployments, this is not a significant security concern.
The registration specifies the MIME type's intended usage as COMMON, reflecting broad applicability in voice messaging systems. It includes optional information such as the file extension .VPM and Macintosh file type code VPIM.
By labeling something as a voice message, anyone looking at the email headers can tell it is voice mail, not a regular email. Usually that is fine, but sometimes it might matter.