💾 Archived View for gemini.bortzmeyer.org › rfc-mirror › rfc3801.txt captured on 2023-11-04 at 14:00:25.
⬅️ Previous capture (2021-11-30)
-=-=-=-=-=-=-
Network Working Group G. Vaudreuil
Request for Comments: 3801 Lucent Technologies
Obsoletes: 2421 G. Parsons
Category: Standards Track Nortel Networks
June 2004
Voice Profile for Internet Mail - version 2 (VPIMv2)
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 (2004).
Abstract
This document specifies a restricted profile of the Internet
multimedia messaging protocols for use between voice processing
server platforms. The profile is referred to as the Voice Profile
for Internet Mail (VPIM) in this document. 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. This profile is intended to specify
the minimum common set of features to allow interworking between
conforming systems.
This document obsoletes RFC 2421 and describes version 2 of the
profile with greater precision. No protocol changes were made in
this revision. A list of changes from RFC 2421 are noted in Appendix
F. Appendix A summarizes the protocol profiles of this version of
VPIM.
Vaudreuil & Parsons Standards Track [Page 1]
RFC 3801 VPIMv2 June 2004
Table of Contents
1. Introduction...................................................3
1.1. Voice Messaging System Limitations.......................3
1.2. Design Goals.............................................4
1.3. Applicability for VPIM...................................5
2. Requirements Language..........................................5
3. Protocol Restrictions..........................................6
4. Voice Message Interchange Format...............................6
4.1. VPIM Message Addressing Formats..........................7
4.2. Message Header Fields....................................9
4.3. MIME Audio Content Descriptions.........................17
4.4. Voice Message Content Types.............................19
4.5. Other MIME Contents.....................................23
4.6. Delivery Status Notification (DSN)......................25
4.7. Message Disposition Notification (MDN)..................26
4.8. Forwarded Messages......................................26
4.9. Reply Messages..........................................27
5. Message Transport Protocol....................................27
5.1. Base SMTP Protocol......................................28
5.2. SMTP Service Extensions.................................28
5.3. ESMTP - SMTP Downgrading................................30
6. Directory Address Resolution..................................30
7. Management Protocols..........................................30
7.1. Network Management......................................31
8. Conformance Requirements......................................31
9. Security Considerations.......................................32
9.1. General Directive.......................................32
9.2. Threats and Problems....................................32
9.3. Security Techniques.....................................33
10. Normative References..........................................33
11. Acknowledgments...............................................36
12. Appendix A - VPIM Requirements Summary........................37
13. Appendix B - Example Voice Messages...........................43
14. Appendix C - Example Error Voice Processing Error Codes.......49
15. Appendix D - Example Voice Processing Disposition Types.......50
16. Appendix E - IANA Registrations...............................50
16.1. Voice Content-Disposition Parameter Definition.........51
16.2. Multipart/Voice-Message MIME Media Type Definition.....51
17. Appendix F - Change History: RFC 2421 (VPIM V2) To This Doc...53
18. Authors' Addresses............................................54
19. Full Copyright Statement......................................55
Vaudreuil & Parsons Standards Track [Page 2]
RFC 3801 VPIMv2 June 2004
1. Introduction
MIME is the Internet multipurpose, multimedia-messaging standard.
This document explicitly recognizes its capabilities and provides a
mechanism for the exchange of various messaging technologies,
primarily voice and facsimile.
Voice messaging evolved as telephone answering service into a full
send, receive, and forward messaging paradigm with unique message
features, semantics and usage patterns. Voice messaging was
introduced on special purpose computers that interface to a telephone
switch and provide call answering and voice messaging services.
Traditionally, messages sent from one voice messaging system to
another were transported using analog networking protocols based on
DTMF signaling and analog voice playback. As the demand for
networking increases, there was a need for a standard high-quality
digital protocol to connect these machines. VPIM has successfully
demonstrated its usefulness as this new standard. VPIM is widely
implemented and is seeing deployment in customer networks. This
document clarifies ambiguities found in the earlier specification and
is consistent with implementation practice. The profile is referred
to as Voice Profile for Internet Mail (VPIM) in this document.
This document specifies a restricted profile of the Internet
multimedia messaging protocols for use between voice processing
server 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. This profile is intended to specify the minimum common set
of features to allow interworking between conforming systems.
This document obsoletes RFC 2421 and describes VPIM version 2 of with
greater precision. No protocol changes were made in this revision.
A list of changes from RFC 2421 are noted in Appendix F. Appendix A
summarizes the protocol profiles of this version of VPIM.
1.1. Voice Messaging System Limitations
The following are typical limitations of voice messaging platforms
that were considered in creating this baseline profile.
1) Text messages are not normally received and often cannot be
easily displayed or viewed. They can often be processed only via
text-to-speech or text-to-fax features not currently present in
many of these machines.
Vaudreuil & Parsons Standards Track [Page 3]
RFC 3801 VPIMv2 June 2004
2) Voice mail machines usually act as an integrated Message
Transfer Agent, Message Store and User Agent. There is typically
no relaying of messages. RFC822 header fields may have limited
use in the context of the limited messaging features currently
deployed.
3) Voice mail message stores are generally not capable of
preserving the full semantics of an Internet message. As such,
use of a voice mail machine for gatewaying is not supported. In
particular, storage of recipient lists, "Received:" lines, and
"Message-ID:" may be limited.
4) Internet-style distribution/exploder mailing lists are not
typically supported. Voice mail machines often implement only
local alias lists, with error-to-sender and reply-to-sender
behavior. Reply-all capabilities using a Cc list are not generally
available.
5) Error reports must be machine-parsable so that helpful
responses can be voiced to users whose only access mechanism is a
telephone.
6) The voice mail systems generally limit address entry to 16 or
fewer numeric characters, and normally do not support alphanumeric
mailbox names. Alpha characters are not generally used for
mailbox identification, as they cannot be easily entered from a
telephone terminal.
It should be noted that newer systems are based natively on SMTP/MIME
and do not suffer these limitations. In particular, some systems may
support media other than voice and fax.
1.2. Design Goals
It is a goal of this profile to make as few restrictions and
additions to the existing Internet mail protocols as possible while
satisfying the requirements for interoperability with current
generation voice messaging systems. This goal is motivated by the
desire to increase the accessibility to digital messaging by enabling
the use of proven existing networking software for rapid development.
This specification is intended for use on a TCP/IP network; however,
it is possible to use the SMTP protocol suite over other transport
protocols. The necessary protocol parameters for such use are
outside the scope of this document.
Vaudreuil & Parsons Standards Track [Page 4]
RFC 3801 VPIMv2 June 2004
This profile is intended to be robust enough to be used in an
environment, such as the global Internet, with installed-base
gateways that do not understand MIME. Full functionality, such as
reliable error messages and binary transport, will require careful
selection of gateways (e.g., via MX records) to be used as VPIM
forwarding agents. Nothing in this document precludes use of
general-purpose MIME email packages to read and compose VPIM
messages. While no special configuration is required to receive VPIM
conforming messages, some may be required to originate conforming
structures.
It is expected that a system administrator who can perform TCP/IP
network configuration will manage a VPIM messaging system. When
using facsimile or multiple voice encodings, it is suggested that the
system administrator maintain a list of the capabilities of the
networked mail machines to reduce the sending of undeliverable
messages due to lack of feature support. Configuration,
implementation and management of these directory-listing capabilities
are local matters.
1.3. Applicability for VPIM
VPIM is intended for the exchange of voice messages between
traditional voice messaging systems and for systems that need to
interoperate with such systems. VPIM is intended connect voice-
messaging systems into special-purpose voice messaging networks.
VPIM may also be used between message store servers and VPIM-aware
clients such as web servers, TUI, and GUI clients. VPIM is not
intended or optimized for downloading to, or sending from commercial
email clients.
Internet Voice Messaging, the subject of a separate standards
initiative, is intended to enable general-purpose email clients to
send and receive voice content through general-purpose message stores
in an interoperable way. IVM may also be a suitable format for
downloading voice messages from a VPIM server to a commercial email
client. It may also be a suitable format for submission of a voice
message from a general-purpose client into a VPIM system.
2. Requirements Language
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].
Vaudreuil & Parsons Standards Track [Page 5]
RFC 3801 VPIMv2 June 2004
3. Protocol Restrictions
This protocol does not limit the number of recipients per message.
Where possible, server implementations should not restrict the number
of recipients in a single message. It is recognized that no
implementation supports unlimited recipients, and that the number of
supported recipients may be quite low.
This protocol does not limit the maximum message length.
Implementers should understand that some machines will be unable to
accept excessively long messages. A mechanism is defined in [SIZE]
to declare the maximum message size supported.
The following sections describe the restrictions and additions to
Internet mail protocols that are required to be conforming with this
VPIM v2 profile. Though various SMTP, ESMTP and MIME features are
described here, the implementer is referred to the relevant RFCs for
complete details. The table in Appendix A summarizes the protocol
details of this profile.
4. Voice Message Interchange Format
The voice message interchange format is a profile of the Internet
Mail Protocol Suite. Any Internet Mail message containing the format
defined in this section is referred to as a VPIM Message in this
document. As a result, this document assumes an understanding of the
Internet Mail specifications. Specifically, VPIM references
components from the message format standard for Internet messages
[RFC822], the Multipurpose Internet Message Extensions [MIME1-5], the
X.400 gateway specification [X.400], and the delivery status and
message disposition notifications [REPORT][DSN][DRPT][STATUS][MDN].
MIME, introduced in [MIME1], is a general-purpose message body format
that is extensible to carry a wide range of body parts. It provides
for encoding binary data so that it can be transported over the 7-bit
text-oriented SMTP protocol. This transport encoding (denoted by the
"Content-Transfer-Encoding:" MIME field) is in addition to the audio
encoding required to generate a binary object.
MIME defines two transport-encoding mechanisms to transform binary
data into a 7-bit representation, one designed for text-like data
("Quoted-Printable"), and one for arbitrary binary data ("Base64").
While Base64 is dramatically more efficient for audio data, either
will work. Where binary transport is available, no transport
encoding is needed, and the data can be labeled as "Binary".
Vaudreuil & Parsons Standards Track [Page 6]
RFC 3801 VPIMv2 June 2004
4.1. VPIM Message Addressing Formats
VPIM addresses SHALL use the RFC 822 format based on the Domain Name
System. This naming system has two components: the local part, used
for username or mailbox identification; and the host part, used for
global machine identification.
4.1.1. VPIM Addresses
The local part of the address shall be a US-ASCII string uniquely
identifying a mailbox on a destination system. For voice messaging,
the local part SHALL be a printable string containing the mailbox ID
of the originator or recipient. While alpha characters and long
mailbox identifiers MAY be permitted, short numeric local parts
SHOULD be used as most voice mail networks rely on numeric mailbox
identifiers to retain compatibility with the limited 10-digit
telephone keypad. As a result, some voice messaging systems may only
be able to handle a numeric local part. The reception of
alphanumeric local parts on these systems may result in the address
being mapped to some locally unique (but confusing to the recipient)
number or, in the worst case the address could be deleted making the
message unreplyable. Additionally, it may be difficult to create
messages on these systems with an alphanumeric local part without
complex key sequences or some form of directory lookup (see 6). The
use of the Domain Name System should be transparent to the user. It
is the responsibility of the voice mail machine to lookup the fully-
qualified domain name (FQDN) based on the address entered by the user
(see 6).
In the absence of a global directory, specification of the local part
is expected to conform to international or private telephone
numbering plans. It is likely that private numbering plans will
prevail and these are left for local definition. However, it is
RECOMMENDED that public telephone numbers be noted according to the
international numbering plan described in [E.164]. The indication
that the local part is a public telephone number is given by a
preceding "+" (the "+" would not be entered from a telephone keypad,
it is added by the system as a flag). Since the primary information
in the numeric scheme is contained by the digits, other character
separators (e.g., "-") may be ignored (i.e., to allow parsing of the
numeric local mailbox) or may be used to recognize distinct portions
of the telephone number (e.g., country code). The specification of
the local part of a VPIM address can be split into the four groups
described below:
1) mailbox number
- for use as a private numbering plan (any number of digits)
- e.g., 2722@lucent.com
Vaudreuil & Parsons Standards Track [Page 7]
RFC 3801 VPIMv2 June 2004
2) mailbox number+extension
- for use as a private numbering plan with extensions
any number of digits, use of "+" as separator
- e.g., 2722+111@Lucent.com
3) +international number
- for international telephone numbers conforming to E.164
maximum of 15 digits
- e.g., +16137637582@vm.nortel.ca
4) +international number+extension
- for international telephone numbers conforming to E.164
maximum of 15 digits, with an extension (e.g., behind a
PBX) that has a maximum of 15 digits.
- e.g., +17035245550+230@ema.org
Note that this address format is designed to be compatible with
current usage within the voice messaging industry. It is not
compatible with the addressing formats of RFCs 2303-2304. It is
expected that as telephony services become more widespread on the
Internet, these addressing formats will converge.
4.1.2. Special Addresses
Special addresses to represent the sender are provided for
compatibility with the conventions of Internet mail. These addresses
do not use numeric local addresses, both to conform to current
Internet practice and to avoid conflict with existing numeric
addressing plans. Two special addresses are RESERVED for use as
follows:
postmaster@domain
By convention, a special mailbox named "postmaster" MUST exist on all
systems. This address is used for diagnostics and should be checked
regularly by the system manager. This mailbox is particularly likely
to receive text messages, which is not normal on a voice-processing
platform. The specific handling of these messages is an individual
implementation choice.
non-mail-user@domain
If a reply to a message is not possible, such as a telephone-
answering message, then the special address "non-mail-user" SHOULD be
used as the originator's address. Any text name such as "Telephone
Answering", or the telephone number if it is available, is permitted.
This special address is used as a token to indicate an unreachable
originator. A conforming implementation MUST NOT permit a reply to an
Vaudreuil & Parsons Standards Track [Page 8]
RFC 3801 VPIMv2 June 2004
address from "non-mail-user". For compatibility with the installed
base of mail user agents, implementations MUST reject the message
when a message addressed to "non-mail-user" is received. The status
code for such NDN's is 5.1.1 "Mailbox does not exist".
Example:
From: Telephone Answering <non-mail-user@mycompany.com>
4.1.3. Distribution Lists
There are many ways to handle distribution list (DL) expansions and
none are 'standard'. A VPIM implementation MAY support DLs. Using a
simple alias is a behavior closest to what many voice mail systems do
today and what is to be used with VPIM messages. A couple of
important features that need special care when DLs are used are:
Reply to the originator - (Address in the RFC822 "Reply-To:" or
"From" field)
Errors to the submitter - (Address in the MAIL FROM field of the
ESMTP exchange or the "Return-Path:"
RFC822 field)
Some proprietary voice messaging protocols include only the recipient
of the particular copy in the envelope and include no "header fields"
except date and per-message features. Most voice messaging systems
do not provide for "Header Information" in their messaging queues and
only include delivery information. As a result, recipient
information MAY be in either the "To:" or "Cc:" header fields. If all
recipients cannot be presented then the recipient header fields
SHOULD be omitted to indicate that an accurate list of recipients
(e.g., for use with a reply-all capability) is not known.
4.2. Message Header Fields
Internet messages contain a header information block. This header
block contains information required to identify the sender, the list
of recipients, the message send time, and other information intended
for user presentation. Except for specialized gateway and mailing
list cases, header fields do not indicate delivery options for the
transport of messages.
Distribution list processors are noted for modifying or adding to the
header fields of messages that pass through them. VPIM systems MUST
be able to accept and ignore header fields that are not defined here.
The following header lines are permitted for use with VPIM messages:
Vaudreuil & Parsons Standards Track [Page 9]
RFC 3801 VPIMv2 June 2004
4.2.1. From
SEND RULES
The originator's fully qualified domain address (a mailbox address
followed by the fully qualified domain name) MUST be present.
Systems conforming with this profile SHOULD provide the text personal
name of the voice message originator in a quoted phrase, if the name
is available. Text names of corporate or positional mailboxes MAY be
provided as a simple string. From: [RFC822]
Example:
From: "Joe S. User" <12145551212@mycompany.com>
From: Technical Support <611@serviceprovider.com>
From: Non-mail-user@myserver.mycompany.com
Voice mail machines may not be able to support separate attributes
for the "From:" header fields and the SMTP MAIL FROM, VPIM-conforming
systems SHOULD set these values to the same address. Use of
addresses different than those present in the "From:" header field
address may result in unanticipated behavior.
RECEIVE RULES
The user listed in the "From:" field MUST be presented in the voice
message envelope of the voice messaging system as the originator of
the message, though the exact presentation is an implementation
decision (e.g., the mailbox ID or the text name MAY be presented).
The "From:" address SHOULD be used for replies (see 4.9).
4.2.2. To
The "To:" field contains the recipient's fully-qualified domain
address.
Example:
To: +12145551213@mycompany.com
SEND RULES
There MAY be one or more "To:" fields in any message. Systems SHOULD
provide a list of recipients only if all recipients are available.
Vaudreuil & Parsons Standards Track [Page 10]
RFC 3801 VPIMv2 June 2004
Systems, such as gateways from protocols or legacy platforms that do
not indicate the complete list of recipients, MAY provide a "To:"
line. Because these systems cannot accurately enumerate all
recipients in the "To:" headers, recipients SHOULD NOT be enumerated.
RECEIVE RULES
Systems conforming to this profile MAY discard the addresses in the
"To:" fields if they are unable to store the information. This
would, of course, make a reply-to-all capability impossible. If
present, the addresses in the "To:" field MAY be used for a reply
message to all recipients.
4.2.3. Cc
The "Cc:" field contains additional recipients' fully qualified
domain addresses. Many voice mail systems maintain only sufficient
envelope information for message delivery and are not capable of
storing or providing a complete list of additional recipients.
SEND RULES
Conforming implementations MAY send "Cc:" lists if all recipients are
known at the time of origination. If not, systems SHOULD omit the
"Cc:" fields to indicate that the full list of recipients is unknown
or otherwise unavailable. The list of disclosed recipients MUST NOT
include undisclosed recipients (i.e., those sent via a blind copy).
Example:
Cc: +12145551213@mycompany.com
RECEIVE RULES
Systems conforming to this profile MAY add all the addresses in the
"Cc:" field to the "To:" field, others MAY discard the addresses in
the "Cc:" fields. If a list of "Cc:" addresses is present, these
addresses MAY be used for a reply message to all recipients.
4.2.4. Date
The "Date:" field contains the date and time the message was sent by
the originator.
SEND RULES
The sending system MUST report the time the message was sent. The
time zone MUST be present and SHOULD be represented in a four-digit
Vaudreuil & Parsons Standards Track [Page 11]
RFC 3801 VPIMv2 June 2004
time zone offset, such as -0500 for North American Eastern Standard
Time. This MAY be supplemented by a time zone name in parentheses,
e.g., "-0700 (PDT)".
Example:
Date: Wed, 28 Jul 96 10:08:49 -0800 (PST)
If the VPIM sender is relaying a message from a system that does not
provide a time stamp, the time of arrival at the gateway system
SHOULD be used as the date.
RECEIVE RULES
Conforming implementations SHOULD be able to convert [RFC822] date
and time stamps into local time
4.2.5. Sender
The "Sender:" field contains the actual address of the originator if
an agent on behalf of the author indicated in the "From:" field sends
the message.
SEND RULES
This header field MAY be sent by VPIM-conforming systems.
RECEIVE RULES
If the address in the "Sender:" field cannot be preserved in the
recipient's message queues or in the next-hop protocol from a
gateway, the field MAY be silently discarded.
4.2.6. Return-Path
The "Return-path:" field is added by the final delivering SMTP
server. If present, it contains the address from the MAIL FROM
parameter of the ESMTP exchange (see [RFC822]). Any error messages
resulting from the delivery failure MUST be sent to this address.
Note that if the "Return-path:" is null ("<>") (e.g., a call answer
message would have no return path) delivery status notifications MUST
NOT be sent.
SEND RULES
The originating system MUST NOT add this header.
Vaudreuil & Parsons Standards Track [Page 12]
RFC 3801 VPIMv2 June 2004
RECEIVE RULES
If the receiving system is incapable of storing the return path (or
MAIL FROM) to be used for subsequent delivery errors (i.e., it is a
gateway to a legacy system or protocol), the receiving system must
otherwise ensure that further delivery errors don't happen. Systems
that do not support the return path MUST ensure that at the time the
message is acknowledged (i.e., when a DSN would be sent), the message
is delivered to the recipient's ultimate mailbox. Non-Delivery
notifications SHOULD NOT be sent after that final delivery.
4.2.7. Message-id
The "Message-Id:" field contains a globally unique per-message
identifier.
SEND RULES
A globally unique message-id MUST be generated for each message sent
from a VPIM-conforming implementation.
Example:
Message-Id: <12345678@mycompany.com>
RECEIVE RULES
When provided in the original message, it MUST be used when sending a
MDN. This identifier MAY be used for tracking and auditing. From
[RFC822]
4.2.8. Reply-To
If present, the "Reply-To:" header provides a preferred address to
which reply messages should be sent (see 4.9). Typically, voice mail
systems can only support one originator of a message so it is likely
that this field will be ignored by the receiving system. From:
[RFC822]
SEND RULES
A conforming system SHOULD NOT send a "Reply-To:" header.
RECEIVE RULES
If a "Reply-To:" field is present, a reply-to-sender message MAY be
sent to the address specified (that is, in lieu of the address in the
"From:" field). If the receiving system (e.g., multi-protocol
Vaudreuil & Parsons Standards Track [Page 13]
RFC 3801 VPIMv2 June 2004
gateway) only supports one address for the originator, then the
address in the "From:" field MUST be used and the "Reply-To:" field
MAY be silently discarded.
4.2.9. Received
The "Received:" field contains trace information added to the
beginning of a RFC822 message by MTAs. This is the only field that
may be added by an MTA. Information in this header is useful for
debugging when using an US-ASCII message reader or a header-parsing
tool. From: [RFC822]
SEND RULES
A VPIM-conforming system MUST add a "Received:" field. When acting
as a gateway, information about the system from which the message was
received SHOULD be included.
RECEIVE RULES
A VPIM-conforming system MUST NOT remove any "Received:" fields when
relaying messages to other MTAs or gateways. These header fields MAY
be ignored or deleted when the message is received at the final
destination.
4.2.10. MIME Version
The "MIME-Version:" field MUST be present to indicate that the
message conforms to [MIME1-5]. Systems conforming with this
specification SHOULD include a comment with the words "(Voice 2.0)".
[VPIM1] defines an earlier version of this profile and uses the token
(Voice 1.0). Example:
MIME-Version: 1.0 (Voice 2.0)
This identifier is intended for information only and SHOULD NOT be
used to semantically identify the message as being a VPIM message.
Instead, the presence of the multipart/voice-message content type
defined in section 18.2 SHOULD be used if identification is
necessary.
4.2.11. Content-Type
The "Content-Type:" header MUST be present to declare the type of
content enclosed in the message. The typical top-level content in a
VPIM Message SHOULD be Multipart/Voice-Message. The allowable
contents are detailed starting in section 4.4 of this document.
From: [MIME2]
Vaudreuil & Parsons Standards Track [Page 14]
RFC 3801 VPIMv2 June 2004
4.2.12. Content-Transfer-Encoding
Because Internet mail was initially specified to carry only 7-bit
US-ASCII text, it may be necessary to encode voice and fax data into
a representation suitable for that environment. The "Content-
Transfer-Encoding:" header describes this transformation if it is
needed.
SEND RULES
An implementation in conformance with this profile SHOULD send audio
and/or facsimile data in "Binary" form when binary message transport
is available (see section 5). When binary transport is not
available, implementations MUST encode the audio and/or facsimile
data as "Base64".
RECEIVE RULES
Conforming implementations MUST recognize and decode the standard
encodings, "Binary" (when binary support is available), "7bit,
"8bit", "Base64" and "Quoted-Printable" per [MIME1]. The detection
and decoding of "Quoted-Printable", "7bit", and "8bit" MUST be
supported in order to meet MIME requirements and to preserve
interoperability with the fullest range of possible devices.
4.2.13. Sensitivity
The "Sensitivity:" field, if present, indicates the requested privacy
level. If no privacy is requested, this field is omitted. The
header definition is as follows:
Sensitivity := "Sensitivity" ":" Sensitivity-value
Sensitivity-value := "Personal" / "Private" / "Company-Confidential"
SEND RULES
A VPIM-conforming implementation MAY include this header to indicate
the sensitivity of a message. If a user marks a message "Private", a
conforming implementation MUST send only the "Private" sensitivity
level. There are no VPIM-specific semantics defined for the values
"Personal" or "Company-Confidential". A conforming implementation
SHOULD NOT send the values "Personal" or "Company-Confidential". If
the message is of "Normal" sensitivity, this field SHOULD be omitted.
From: [X.400]
Vaudreuil & Parsons Standards Track [Page 15]
RFC 3801 VPIMv2 June 2004
RECEIVE RULES
If a "Sensitivity:" field with a value of "Private" is present in the
message, a conforming system MUST prohibit the recipient from
forwarding this message to any other user. A conforming system,
however, SHOULD allow the responder to reply to a sensitive message,
but SHOULD NOT include the original message content. The responder
MAY set the sensitivity of the reply message.
A receiving system MAY ignore sensitivity values of "Personal" and
"Company Confidential".
If the receiving system does not support privacy and the sensitivity
is "Private", a negative delivery status notification MUST be sent to
the originator with the appropriate status code (5.6.0) "Other or
undefined protocol status" indicating that privacy could not be
assured. The message contents SHOULD be returned to the sender to
allow for a voice context with the notification. A non-delivery
notification to a private message SHOULD NOT be tagged private since
it will be sent to the originator. From: [X.400]
A message with no privacy explicitly noted (i.e., no header) or with
"Normal" sensitivity has no special treatment.
4.2.14. Importance
Indicates the requested importance to be given by the receiving
system. If no special importance is requested, this header MAY be
omitted and the value of the absent header assumed to be "normal".
From: [X.400]
Importance := "Importance" ":" importance-value
Importance-value := "low" / "normal" / "high"
SEND RULES
Conforming implementations MAY include this header to indicate the
importance of a message.
RECEIVE RULES
If the receiving system does not support "Importance:", the attribute
MAY be silently dropped.
Vaudreuil & Parsons Standards Track [Page 16]
RFC 3801 VPIMv2 June 2004
4.2.15. Subject
The "Subject:" field is often provided by email systems but is not
widely supported on voice mail platforms. From: [RFC822]
SEND RULES
For compatibility with text-based mailbox interfaces, a text subject
field SHOULD be generated by a conforming implementation. It is
RECOMMENDED that voice-messaging systems that do not support any text
user interfaces (e.g., access only by a telephone) insert a generic
subject header of "VPIM Message" or "Voice Message" for the benefit
of GUI-enabled recipients.
RECEIVE RULES
It is anticipated that many voice-only systems will be incapable of
storing the subject line. The subject MAY be discarded by a
receiving system.
4.3. MIME Audio Content Descriptions
4.3.1. Content-Description
This field MAY be present to facilitate the text identification of
these body parts in simple email readers. Any values may be used.
Example:
Content-Description: Big Telco Voice Message
SEND RULES
This field MAY be added to a voice body part to offer a freeform
description of the voice content. It is useful to incorporate the
values for Content-Disposition with additional descriptions. For
example, this can be used to indicate product name or transcoding
records.
RECEIVE RULES
This field MAY be displayed to the recipient. However, since it is
only informative it MAY be ignored.
Vaudreuil & Parsons Standards Track [Page 17]
RFC 3801 VPIMv2 June 2004
4.3.2. Content-Disposition
This field MUST be present to allow the parsable identification of
body parts within a VPIM voice message. This is especially useful
if, as is typical, more than one Audio/* body occurs within a single
level (e.g., Multipart/Voice-Message). Since a VPIM voice message is
intended to be automatically played in the order in which the audio
contents occur, the audio contents MUST always be of disposition
inline. However, it is still useful to include a filename value, so
this SHOULD be present if this information is available. From:
[DISP]
SEND RULES
In order to distinguish between the various types of audio contents
in a VPIM voice message a new disposition parameter "voice" is
defined with IANA (see section 18.1) with the parameter values below
to be used as appropriate:
Audio-Type := "voice" "=" Audio-type-value
Audio-type-value := "Voice-Message" / "Voice-Message-Notification" /
"Originator-Spoken-Name" /"Recipient-Spoken-Name" /"Spoken-Subject"
Voice-Message - the primary voice message,
Voice-Message-Notification - a spoken delivery notification
or spoken disposition notification,
Originator-Spoken-Name - the spoken name of the originator,
Recipient-Spoken-Name - the spoken name of the recipient(s) if
available to the originator
Spoken-Subject- the spoken subject of the message, typically
spoken by the originator
Note that there SHOULD only be one instance of each of these types of
audio contents per message level. Additional instances of a given
type (i.e., parameter value) MAY occur within an attached forwarded
or reply voice message. If there are multiple recipients for a given
message, recipient-spoken-name MUST NOT be used.
RECEIVE RULES
Implementations SHOULD use this header. However, those that do not
understand the "voice" parameter (or the "Content-Disposition:"
header) can safely ignore it, and will present the audio body parts
in order (but will not be able to distinguish between them). If more
than one instance of the "voice" parameter type value is encountered
at one level (e.g., multiple 'Voice-Message' tagged contents) then
they SHOULD be presented together.
Vaudreuil & Parsons Standards Track [Page 18]
RFC 3801 VPIMv2 June 2004
4.3.3. Content-Duration
The "Content-Duration:" header provides an indication of the audio
length in seconds of the segment.
Example:
Content-Duration: 33
SEND RULES
This field MAY be present to allow the specification of the length of
the audio body part in seconds.
RECEIVE RULES
The use of this field on reception is a local implementation issue.
From: [DUR]
4.3.4. Content-Language:
This field MAY be present to allow the specification of the spoken
language of the audio body part. The encoding is defined in [LANG].
Example for UK English:
Content-Language: en-UK
SEND RULES
A sending system MAY add this field to indicate the language of the
voice. The determination of this (e.g., automated or user-selected)
is a local implementation issue.
RECEIVE RULES
The use of this field on reception is a local implementation issue.
It MAY be used as a hint to the recipient (e.g., end-user or an
automated translation process) as to the language of the voice
message.
4.4. Voice Message Content Types
The content types described in this section are identified for use
within the Multipart/Voice-Message content. This content is referred
to as a "VPIM message" in this document and is the fundamental part
of a "VPIM message".
Vaudreuil & Parsons Standards Track [Page 19]
RFC 3801 VPIMv2 June 2004
Only the contents profiled can be sent within a VPIM voice message
construct (i.e., the Multipart/Voice-Message content type) to form a
simple or a more complex structure (several examples are given in
Appendix B). The presence of other contents within a VPIM voice
message is not permitted. In the absence of a bilateral agreement,
conforming implementations MUST NOT create a message containing
prohibited contents. In the spirit of liberal acceptance, a
conforming implementation MAY accept and render prohibited content.
Systems unable to accept or render prohibited contents MAY discard
the prohibited contents as necessary to deliver the acceptable
content. When multiple contents are present within the
Multipart/Voice-Message, they SHOULD be presented to the user in the
order that they appear in the message.
Some deployed implementations based on a common interpretation of the
original VPIM v2 specification reject messages with prohibited
content rather than discard the unsupported contents. For
interoperability with these systems, it is especially important that
prohibited contents not be sent within a Multipart/Voice-Message.
4.4.1. Multipart/Voice-Message
This MIME multipart structure provides a mechanism for packaging a
voice message into one container that is tagged as VPIM v2
conforming. 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).
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 this specification. 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).
SEND RULES
The Multipart/Voice-Message content-type MUST only contain the
profiled media and content types specified in this section (i.e.,
Audio/*, Image/*, and Message/RFC822). The most common will be:
spoken name, spoken subject, the message itself, and an attached fax.
Forwarded messages are created by simply using the Message/RFC822
construct.
Vaudreuil & Parsons Standards Track [Page 20]
RFC 3801 VPIMv2 June 2004
Conformant implementations MUST use Multipart/Voice-Message in a VPIM
message. In most cases, this Multipart/Voice-Message Content-Type
will be the top level but may be included within a Message/RFC822 if
the message is forwarded or within a multipart/mixed when more than
one message is being forwarded.
RECEIVE RULES
Conformant implementations MUST recognize the Multipart/Voice-Message
content (whether it is a top-level content or contained in a
Multipart/Mixed) and MUST be able to separate the contents (e.g.,
spoken name or spoken subject).
The semantic of Multipart/Voice-Message (defined in section 18.2) is
identical to Multipart/Mixed and may be interpreted as that by
systems that do not recognize this content-type.
4.4.2. Message/RFC822
SEND RULES
MIME requires support of the Message/RFC822 message encapsulation
body part. This body part SHOULD be used within a Multipart/Voice-
Message to forward complete messages (see 4.8) or to reply with
original content (see 4.9). From: [MIME2]
RECEIVE RULES
The receiving system MUST accept this format and SHOULD treat this
attachment as a forwarded message. The receiving system MAY flatten
the forwarding structure (i.e., remove this construct to leave
multiple voice contents or even concatenate the voice contents to fit
in a recipient's mailbox), if necessary.
4.4.3. Audio/32KADPCM
SEND RULES
An implementation conforming to this profile MUST send Audio/32KADPCM
by default for voice [ADPCM]. This encoding is a moderately-
compressed encoding with a data rate of 32 kbits/second using
moderate processing resources. Typically, this body contains several
minutes of message content; however, if used for spoken name or
subject the content is expected to be considerably shorter (i.e.,
about 5 and 10 seconds respectively).
Vaudreuil & Parsons Standards Track [Page 21]
RFC 3801 VPIMv2 June 2004
RECEIVE RULES
Receivers MUST be able to accept and decode Audio/32KADPCM. If an
implementation can only handle one voice body, then multiple voice
bodies (if present) SHOULD be concatenated, and MUST NOT be
discarded. If concatenated, the contents SHOULD be in the same order
they appeared in the multipart.
4.4.4. Image/TIFF
A common image encoding for facsimile, known as TIFF-F, is a
derivative of the Tag Image File Format (TIFF) and is described in
several documents. For the purposes of VPIM, the F Profile of TIFF
for Facsimile (TIFF-F) is defined in [TIFF-F], and the Image/TIFF
MIME content-type is defined in [TIFFREG]. While there are several
formats of TIFF, only TIFF-F is profiled for use within
Multipart/Voice-Message. Further, since the TIFF-F file format is
used in a store-and-forward mode with VPIM, the image MUST be encoded
so that there is only one image strip per facsimile page.
SEND RULES
All VPIM implementations that support facsimile MUST generate TIFF-F
compatible facsimile contents in the Image/TIFF subtype using the
application=faxbw encoding by default. If the VPIM message is a
voice- annotated fax, the implementation SHOULD send this fax content
in Multipart/Voice-Message. If the message is a simple fax, an
implementation MAY send it without using the Multipart/Voice-Message
to be more compatible with fax-only (RFC 2305) implementations.
While any valid MIME body header MAY be used (e.g., Content-
Disposition to indicate the filename), none are specified to have
special semantics for VPIM and MAY be ignored. Note that the
content-type parameter application=faxbw MUST be included in outbound
messages.
RECEIVE RULES
Not all VPIM systems support fax, but all SHOULD accept it within the
multipart/voice-message. Within a Multipart/Voice-Message, a
receiving system that cannot render fax content SHOULD accept the
voice content of a VPIM message and discard the fax content. Outside
a Multipart/Voice-Message, a recipient system MAY reject (with
appropriate NDN) the entire message if it cannot store or is not
capable of rendering a message with fax attachments. VPIM conforming
systems MAY support fax outside of (or without) the Multipart/Voice-
Message.
Vaudreuil & Parsons Standards Track [Page 22]
RFC 3801 VPIMv2 June 2004
Some deployed implementations based on a common interpretation of the
original VPIM V2 specification reject messages with fax content
within the Multipart/Voice-Message rather than discard the
unsupported contents. These systems will return the message to the
sender with an NDN indicating lack of support for fax.
4.5. Other MIME Contents
The following MIME contents (with the exception of multipart/mixed in
section 4.5.1) MAY be included within a multipart/voice message.
Other contents MUST NOT be included. Their handling is a local
implementation issue. Multipart/mixed is included to promote
interoperability with a wider range of systems and also to allow the
creation of more complex multimedia messages (with a VPIM message as
one part).
4.5.1. Multipart/Mixed
This common MIME content-type allows the enclosing of several body
parts in a single message.
SEND RULES
A VPIM voice message (i.e., multipart/voice-message) MAY be included
within a message with a Multipart/Mixed top-level content type.
Typically, this would only be used when mixing non-voice and non-fax
contents with a voice message.
RECEIVE RULES
Such a message is not itself a VPIM message and the handling of such
a construct is outside the scope of the VPIM profile. However, an
the spirit of liberal acceptance, a conforming implementation MUST
accept and render a VPIM voice message contained in a
Multipart/Mixed.
4.5.2. Text/Directory
SEND RULES
This content was profiled in the original specification of VPIM v2 as
a means of transporting contact information from the sender to the
recipient. This usage did not find widespread adoption and is no
longer a feature of VPIM V2. Conforming implementations SHOULD NOT
send the Text/Directory content type.
Vaudreuil & Parsons Standards Track [Page 23]
RFC 3801 VPIMv2 June 2004
RECEIVE RULES
For compatibility with an earlier specification of VPIM v2, the
Text/Directory content type MUST be accepted by a conforming
implementation, but need not be stored, processed, or rendered to the
recipient.
4.5.3. Proprietary Voice or Fax Formats
Use of any other encoding except the required codecs reduces
interoperability in the absence of explicit knowledge about the
capabilities of the recipient. A conforming implementation SHOULD
NOT use any other encoding unless a unique identifier is registered
with the IANA prior to use (see [MIME4]). The voice encodings SHOULD
be registered as subtypes of Audio. The fax encodings SHOULD be
registered as subtypes of Image.
SEND RULES
Proprietary voice encoding formats or other standard formats SHOULD
NOT be sent under this profile unless the sender has a reasonable
expectation that the recipient will accept the encoding. In
practice, this requires explicit per-destination configuration
information maintained either in a directory, personal address book,
or gateway configuration tables.
RECEIVE RULES
Systems MAY accept other Audio/* or Image/* content types if they can
decode them. Systems which receive Audio/* or Image/* content types
which they are unable to deposit or unable to render MUST return the
message (and SHOULD include the original content) to the originator
with an NDN indicating media not supported.
4.5.4. Text/Plain
MIME requires support of the basic Text/Plain content type (with the
US-ASCII character set). This content type has limited applicability
within the voice-messaging environment. However, because VPIM is a
MIME profile, MIME requirements SHOULD be met.
SEND RULES
Conforming VPIM implementations SHOULD NOT send the Text/Plain
content-type. Implementations MAY send the Text/Plain content-type
outside the Multipart/Voice-Message.
Vaudreuil & Parsons Standards Track [Page 24]
RFC 3801 VPIMv2 June 2004
RECEIVE RULES
Within a Multipart/Voice-Message, the Text/Plain content-type MAY be
dropped from the message, if necessary, to deliver the audio/fax
components. The recipient SHOULD NOT reject the entire message if
the text component cannot be accepted or rendered.
Outside a Multipart/Voice-Message, conforming implementations MUST
accept Text/Plain; however, specific handling is left as an
implementation decision. From: [MIME2]
Some deployed implementations based on a common interpretation of the
original VPIM V2 specification reject messages with any text content
rather than discard the unsupported contents. These systems will
return the message to the sender with an NDN indicating lack of
support for text.
4.6. Delivery Status Notification (DSN)
A DSN is a notification of delivery (positive DSN), non-delivery
(negative DSN), or temporary delivery delay (delayed DSN). The top-
level content-type of a DSN is Multipart/Report, which is defined in
[REPORT]. The content-type which distinguishes DSN's from other
types of notifications is Message/Delivery-Status, which is defined
in [DSN].
SEND RULES
A VPIM-compliant implementation MUST be able to send DSN's that
conform to [REPORT] and [DSN]. Unless requested otherwise, a non-
delivery DSN MUST be sent when any form of non-delivery of a message
occurs.
A VPIM-compliant implementation SHOULD provide a spoken delivery
status in the "human-readable" body part of the DSN, but MAY provide
a textual status.
RECEIVE RULES
A VPIM-compliant implementation MUST be able to receive DSN's that
conform to [REPORT] and [DSN].
A VPIM-compliant implementation MUST be able to receive a DSN whose
"human-readable" body part contains a spoken delivery status phrase
or a textual description. Though subsequent use of the phrase or
text is a local implementation issue, the intent of the DSN MUST be
presented to the end user.
Vaudreuil & Parsons Standards Track [Page 25]
RFC 3801 VPIMv2 June 2004
4.7. Message Disposition Notification (MDN)
An MDN is a notification indicating what happens to a message after
it is deposited in the recipient's mailbox. An MDN can be positive
(message was read/played/rendered/etc.) or negative (message was
deleted before recipient could see it, etc.). The top-level
content-type of a MDN is Multipart/Report, which is defined in
[REPORT]. The content-type which distinguishes MDN's from other
types of notifications is Message/Disposition-Notification, which is
defined in [MDN].
SEND RULES
A VPIM-compliant implementation SHOULD support the ability to request
MDNs. This is done via the use of the "Disposition-Notification-To:"
header field as defined in [MDN].
A VPIM-compliant implementation SHOULD support the ability to send
MDNs, but these MDNs MUST conform to [REPORT] and [MDN].
When sending an MDN, a VPIM-compliant implementation SHOULD provide a
spoken message disposition in the "human-readable" body part of the
MDN, but MAY provide a textual status.
RECEIVE RULES
A VPIM-compliant implementation SHOULD respond to an MDN request with
an MDN response.
A VPIM-compliant implementation MUST be able to receive MDNs that
conform to [REPORT] and [MDN], if it is capable of requesting MDNs.
If a VPIM-compliant implementation is capable of receiving MDNs, it
MUST be able to receive a MDN whose "human-readable" body part
contains a spoken message disposition phrase or a textual disposition
description. Though subsequent use of the phrase or text is a local
implementation issue, the intent of the MDN MUST be presented to the
end user.
4.8. Forwarded Messages
VPIM v2 explicitly supports the forwarding of voice and fax content
with voice or fax annotation. However, only the two constructs
described below are acceptable in a VPIM message. Since only the
first (i.e., Message/RFC822) can be recognized as a forwarded message
(or even multiple forwarded messages), it is RECOMMENDED that this
construct be used whenever possible.
Vaudreuil & Parsons Standards Track [Page 26]
RFC 3801 VPIMv2 June 2004
Forwarded VPIM messages SHOULD be sent as a Multipart/Voice-Message
with the entire original message enclosed in a Message/RFC822
content-type and the annotation as a separate Audio/* or Image/* body
part. If the RFC822 header fields are not available for the
forwarded content, simulated header fields with available information
SHOULD be constructed to indicate the original sending timestamp, and
the original sender as indicated in the "From:" field. Note that at
least one of "From:", "Subject:", or "Date:" MUST be present. As
well, the Message/RFC822 content MUST include at least the "MIME-
Version:", and "Content-Type:" header fields. From: [MIME2]
In the event that forwarding information is lost, the entire audio
content MAY be sent as a single Audio/* segment without including any
forwarding semantics. An example of this loss is an AMIS message
being forwarded through an AMIS-to-VPIM gateway.
4.9. Reply Messages
VPIM v2 explicitly supports replying to received messages.
Support of multiple originator header fields in a reply message is
often not possible on voice messaging systems, so it may be necessary
to choose only one when gatewaying a VPIM message to another voice
message system. However, implementers should note that this may make
it impossible to send DSN's, MDN's, and replies to their proper
destinations.
In some cases, replying to a message is not possible, such as with a
message created by telephone answering (i.e., classic voice mail).
In this case, the From field SHOULD contain the special address non-
mail-user@domain (see 4.1.2). The recipient's VPIM system SHOULD NOT
offer the option to reply to this kind of message (unless an
outcalling feature is offered - which is out of scope for VPIM).
5. Message Transport Protocol
Messages are transported between voice mail machines using the
Internet Extended Simple Mail Transfer Protocol (ESMTP). All
information required for proper delivery of the message is included
in the ESMTP dialog. This information, including the sender and
recipient addresses, is commonly referred to as the message
"envelope". This information is equivalent to the message control
block in many analog voice messaging protocols.
ESMTP is a general-purpose messaging protocol, designed both to send
mail and to allow terminal console messaging. Simple Mail Transport
Protocol (SMTP) was originally created for the exchange of US-ASCII
7-bit text messages. Binary and 8-bit text messages have
Vaudreuil & Parsons Standards Track [Page 27]
RFC 3801 VPIMv2 June 2004
traditionally been transported by encoding the messages into a 7-bit
text-like form. [ESMTP] formalized an extension mechanism for SMTP,
and subsequent RFCs have defined 8-bit text networking, command
streaming, binary networking, and extensions to permit the
declaration of message size for the efficient transmission of large
messages such as multi-minute voice mail.
The following sections list ESMTP commands, keywords, and parameters
that are required and those that are optional for conformance to this
profile.
5.1. Base SMTP Protocol
A conforming system MUST implement all mandatory SMTP and ESMTP
commands. Any defined optional command or parameter MAY be
supported.
5.2. SMTP Service Extensions
VPIM utilizes a number of SMTP Service Extensions to provide full-
featured voice messaging service. The following extensions are
profiled for use with VPIM:
5.2.1. DSN Extension
The DSN extension defines a mechanism which allows an SMTP client to
specify (a) DSN's should be generated under certain conditions, (b)
whether such DSN's should return the contents of the message, and (c)
additional information, to be returned with a DSN, that allows the
sender to identify both the recipient(s) for which the DSN was
issued, and the transaction in which the original message was sent.
The DSN extension MUST be supported by VPIM conforming
implementations.
In addition, beyond the requirements of [DRPT], conforming
implementations MUST support NOTIFY parameter on the RCPT command to
allow indication of when the originator requests a notification. The
RET parameter SHOULD be supported to return the original message with
the notification. Parameters ORCPT and ENVID MAY also be supported.
From: [DRPT]
5.2.2. SIZE Extension
The SIZE extension defines a mechanism whereby an SMTP client and
server may interact to give the server an opportunity to decline to
accept a message (perhaps temporarily) based on the client's estimate
of the message size. From: [SIZE]
Vaudreuil & Parsons Standards Track [Page 28]
RFC 3801 VPIMv2 June 2004
The SIZE extension MUST be supported by VPIM-compliant
implementations.
5.2.3. ENHANCEDSTATUSCODES Extension
The ENHANCEDSTATUSCODES extension defines a mechanism whereby an SMTP
server augments its responses with the enhanced mail system status
codes defined in [CODES]. These codes can then be used to provide
more informative explanations of error conditions. From: [STATUS]
The ENHANCEDSTATUSCODES extension SHOULD be supported by VPIM-
compliant implementations.
5.2.4. PIPELINING Extension
The PIPELINING extension defines a mechanism whereby an SMTP server
can indicate the extent of its ability to accept multiple commands in
a single TCP send operation. Using a single TCP send operation for
multiple commands can improve SMTP performance significantly. From
[PIPE]
The PIPELINING extension SHOULD be supported by VPIM-compliant
implementations.
5.2.5. CHUNKING Extension
The CHUNKING extension defines a mechanism that enables an SMTP
client and server to negotiate the use of the message data transfer
command "BDAT" (in alternative to the DATA command) for efficiently
sending large MIME messages. From: [BINARY]
The CHUNKING extension MAY be supported by VPIM-compliant
implementations.
5.2.6. BINARYMIME Extension
The BINARYMIME extension defines a mechanism that enables an SMTP
client and server to negotiate the transfer of unencoded binary
message data utilizing the BDAT command. From: [BINARY]
The BINARYMIME extension MAY be supported by VPIM-compliant
implementations. Note that [BINARY] specifies that if BINARYMIME is
to be supported, then CHUNKING has to be supported by definition.
Vaudreuil & Parsons Standards Track [Page 29]
RFC 3801 VPIMv2 June 2004
5.3. ESMTP - SMTP Downgrading
The SMTP extensions suggested or required for conformance to VPIM
fall into two categories. The first category includes features that
increase the efficiency of the transport system such as SIZE,
BINARYMIME, and PIPELINING. In the event of a downgrade to a less-
functional transport system, these features can be dropped with no
functional change to the sender or recipient.
The second category of features is transport extensions in support of
new functions. DSN and ENHANCEDSTATUSCODES provide essential
improvements in the handling of delivery status notifications to
bring email to the level of reliability expected of Voice Mail. To
ensure a consistent level of service across an intranet or the global
Internet, it is essential that VPIM-conforming ESMTP support the DSN
extension at all hops between a VPIM originating system and the
recipient system. In the situation where a "downgrade" is
unavoidable a relay hop may be forced (by the next hop) to forward a
VPIM message without the ESMTP request for delivery status
notification. It is RECOMMENDED that the downgrading system should
continue to attempt to deliver the message, but MUST send an
appropriate delivery status notification to the originator, e.g., the
message left an ESMTP host and was sent relayed to a non-DSN-aware
destination, and this may be the last DSN received.
6. Directory Address Resolution
It is the responsibility of a VPIM system to provide the fully-
qualified domain name (FQDN) of the recipient based on the address
entered by the user (if the entered address is not already a FQDN).
This would typically be an issue on systems that offer only a
telephone user interface. The mapping of the dialed target number to
a routable FQDN address, allowing delivery to the destination system,
can be accomplished through implementation-specific means.
To facilitate a local cache, an implementation may wish to populate
local directories with the first and last names, as well as the
senders' spoken name information extracted from received messages.
Addresses or names parsed from the header fields of VPIM messages MAY
be used to populate directories.
7. Management Protocols
The Internet protocols provide a mechanism for the management of
messaging systems, from the management of the physical network
through the management of the message queues. SNMP SHOULD be
supported on a VPIM-conforming machine.
Vaudreuil & Parsons Standards Track [Page 30]
RFC 3801 VPIMv2 June 2004
7.1. Network Management
The digital interface to the VM and the TCP/IP protocols MAY be
managed. MIB II MAY be implemented to provide basic statistics and
reporting of TCP and IP protocol performance [MIB II].
8. Conformance Requirements
VPIM is a messaging application that will be supported in several
environments and be supported on differing devices. These
environments include traditional voice processing systems, desktop
voice messaging systems, store-and-forward relays, and protocol
translation gateways.
In order to accommodate all environments, this document defines two
areas of conformance: transport and content.
Transport-conformant systems will pass VPIM messages in a store-and-
forward manner with assured delivery notifications and without the
loss of information. It is expected that most store-and-forward
Internet mail-based messaging systems will be VPIM transport-
conformant.
Content-conformant systems will generate and interpret VPIM messages.
Conformance in the generation of VPIM messages indicates that the
restrictions of this profile are honored. Only contents specified in
this profile or extensions agreed to by bilateral agreement may be
sent. Conformance in the interpretation of VPIM messages indicates
that all VPIM content types and constructs can be received; that all
mandatory VPIM content types can be decoded and presented to the
recipient in an appropriate manner; and that any unrenderable
contents result in the appropriate notification.
A summary of the conformance requirements is contained in Appendix A.
VPIM end systems are expected to be both transport- and content-
conformant. Voice messaging systems and protocol conversion gateways
are considered end systems.
Relay systems are expected to be transport-conformant in order to
receive and send conforming messages. However, they must also create
VPIM-conforming delivery status notifications in the event of
delivery problems.
Desktop Email clients that support VPIM are expected to be content-
conformant. Desktop email clients use various protocols and API's
for exchanging messages with the local message store and message
transport system. While these clients may benefit from VPIM
Vaudreuil & Parsons Standards Track [Page 31]
RFC 3801 VPIMv2 June 2004
transport capabilities, specific client-server requirements are out-
of-scope for this document.
9. Security Considerations
9.1. General Directive
This document is a profile of existing Internet mail protocols. To
maintain interoperability with Internet mail, any security to be
provided should be part of the Internet security infrastructure,
rather than a new mechanism or some other mechanism outside of the
Internet infrastructure.
9.2. Threats and Problems
Both Internet mail and voice messaging have their own set of threats
and countermeasures. As such, this specification does not create any
security issues not already existing in the profiled Internet mail
and voice mail protocols themselves. This section attends only to
the set of additional threats that ensue from integrating the two
services.
9.2.1. Spoofed sender
The actual sender of the voice message might not be the same as that
specified in the "Sender:" or "From:" message header fields or the
MAIL FROM address from the SMTP envelope. In a tightly constrained
environment, sufficient physical and software controls may be able to
ensure prevention of this problem. In addition, the recognition of
the sender's voice may provide confidence of the sender's identity
irrespective of that specified in "Sender:" or "From:". It should be
recognized that SMTP implementations do not provide inherent
authentication of the senders of messages, nor are sites under
obligation to provide such authentication.
9.2.2. Unsolicited voice mail
Assigning an Internet mail address to a voice mailbox opens the
possibility of receiving unsolicited messages (either text or voice
mail). Traditionally, voice mail systems operated in closed
environments and were not susceptible to unknown senders. Voice mail
users have a higher expectation of mailbox privacy and may consider
such messages as a security breach. Many Internet mail systems are
choosing to block all messages from unknown sources in an attempt to
curb this problem.
Vaudreuil & Parsons Standards Track [Page 32]
RFC 3801 VPIMv2 June 2004
9.2.3. Message disclosure
Users of voice messaging systems have an expectation of a level of
message privacy that is higher than the level provided by Internet
mail without security enhancements. This expectation of privacy by
users SHOULD be preserved as much as possible.
9.3. Security Techniques
Sufficient physical and software control may be acceptable in
constrained environments. Further, the profile specified in this
document does not in any way preclude the use of any Internet object
or channel security protocol to encrypt, authenticate, or non-
repudiate the messages.
10. Normative References
[8BIT] Klensin, J., Freed, N., Rose, M., Stefferud, E. and D.
Crocker, "SMTP Service Extension for 8bit-MIMEtransport",
RFC 1652, July 1994.
[ADPCM] Vaudreuil, G. and G. Parsons, "Toll Quality Voice - 32
kbit/s Adaptive Differential Pulse Code Modulation (ADPCM)
MIME Sub-type Registration", RFC 3802, June 2004.
[AMIS-A] Audio Messaging Interchange Specifications (AMIS) - Analog
Protocol Version 1, Issue 2, February 1992.
[AMIS-D] Audio Messaging Interchange Specifications (AMIS) - Digital
Protocol Version 1, Issue 3, August 1993.
[BINARY] Vaudreuil, G., "SMTP Service Extensions for Transmission of
Large and Binary MIME Messages", RFC 3030, December 2000.
[CODES] Vaudreuil, G. "Enhanced Mail System Status Codes", RFC
1893, January 1996.
[MIMEDIR] Dawson, F., Howes, T. and M. Smith, "A MIME Content-Type
for Directory Information", RFC 2425, September 1998.
[DISP] Troost, R. and S. Dorner, "Communicating Presentation
Information in Internet Messages: The Content-Disposition
Header", RFC 2183, August 1997.
[DNS1] Mockapetris, P., "Domain names - implementation and
specification", RFC 1035, November 1987.
Vaudreuil & Parsons Standards Track [Page 33]
RFC 3801 VPIMv2 June 2004
[DNS2] Mockapetris, P., "Domain names - concepts and facilities",
RFC 1034, November 1987.
[DRPT] Moore, K., "Simple Mail Transfer Protocol (SMTP) Service
Extension for Delivery Status Notifications (DSNs)", RFC
3461, January 2003.
[DSN] Moore, K. and G. Vaudreuil, "An Extensible Message Format
for Delivery Status Notifications", RFC 3464, January 2003.
[DUR] Parsons, G. and G. Vaudreuil, "Content Duration MIME Header
Definition", RFC 3803, June 2004.
[E164] CCITT Recommendation E.164 (1991), Telephone Network and
ISDN Operation, Numbering, Routing and Mobile Service -
Numbering Plan for the ISDN Era.
[ESMTP] Klensin, J., "Simple Mail Transfer Protocol", RFC 2821,
April 2001.
[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).
[HOSTREQ] Braden, R., "Requirements for Internet Hosts -- Application
and Support", STD 3, RFC 1123, October 1989.
[LANG] Alvestrand, H., "Tags for the Identification of Languages",
BCP 47, RFC 3066, January 2001.
[MDN] Hansen, T., Ed. and G. Vaudreuil, Ed., "Message Disposition
Notification", RFC 3798, May 2004.
[MIB II] Rose, M., "Management Information Base for Network
Management of TCP/IP-based internets: MIB-II", RFC 1213,
March 1991.
[MIME1] Freed, N. and N. Borenstein, "Multipurpose Internet Mail
Extensions (MIME) Part One: Format of Internet Message
Bodies", RFC 2045, November 1996.
[MIME2] Freed, N. and N. Borenstein, "Multipurpose Internet Mail
Extensions (MIME) Part Two: Media Types ", RFC 2046,
November 1996.
Vaudreuil & Parsons Standards Track [Page 34]
RFC 3801 VPIMv2 June 2004
[MIME3] Moore, K., "Multipurpose Internet Mail Extensions (MIME)
Part Three: Message Header Extensions for Non-ASCII Text ",
RFC 2047, November 1996.
[MIME4] Freed, N., Klensin, J. and J. Postel, "Multipurpose
Internet Mail Extensions (MIME) Part Four: Registration
Procedures", RFC 2048, November 1996.
[MIME5] Freed, N. and N. Borenstein, "Multipurpose Internet Mail
Extensions (MIME) Part Five: Conformance Criteria and
Examples ", RFC 2049, November 1996.
[PIPE] Freed, N.and A. Cargille, "SMTP Service Extension for
Command Pipelining" STD 60, RFC 2920, September 2000.
[REPORT] Vaudreuil, G., "The Multipart/Report Content Type for the
Reporting of Mail System Administrative Messages", RFC
3462, January 2003.
[REQ] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC822] Crocker, D., "Standard for the Format of ARPA Internet Text
Messages", STD 11, RFC 822, August 1982.
[SIZE] Klensin, J., Freed, N. and K. Moore, "SMTP Service
Extensions for Message Size Declaration" STD 10, RFC 1870,
November 1995.
[STATUS] Freed, N., "SMTP Service Extension for Returning Enhanced
Error Codes", RFC 2034, October 1996.
[TIFF-F] Parsons, G. and J. Rafferty, "Tag Image File Format:
Application F", RFC 2306, March 1998.
[TIFFREG] Parsons, G., Rafferty, J. and S. Zilles, "Tag Image File
Format: image/tiff - MIME sub-type registration", RFC 2302,
March 1998.
[V-MSG] Vaudreuil, G. and G. Parsons, "VPIM Voice Message MIME
Sub-type Registration", RFC 2423, September 1998.
[VCARD] Dawson, F. and T. Howes, "vCard MIME Directory Profile" RFC
2426, September 1998.
[VPIM1] Vaudreuil, G., "Voice Profile for Internet Mail", RFC 1911,
February 1996.
Vaudreuil & Parsons Standards Track [Page 35]
RFC 3801 VPIMv2 June 2004
[VPIM2] Vaudreuil, G. and G. Parsons, "Voice Profile for Internet
Mail, Version 2", RFC 2421, September 1998.
[X.400] CCITT/ISO, "CCITT Recommendations X.400/ ISO/IEC 10021-1,
Message Handling: System and Service Overview", December
1988.
11. Acknowledgments
The authors would like to offer a special thanks to the Electronic
Messaging Association (EMA), especially the members of the Voice
Messaging Committee, and the IETF VPIM Work Group, for their support
of the VPIM specification and the efforts they have made to ensure
its success.
Vaudreuil & Parsons Standards Track [Page 36]
RFC 3801 VPIMv2 June 2004
12. Appendix A - VPIM Requirements Summary
The following table summarizes the profile of VPIM version 2 detailed
in this document. Since in many cases it is not possible to simplify
the qualifications for supporting each feature this appendix is
informative. The reader is recommended to read the complete
explanation of each feature in the referenced section. The text in
the previous sections shall be deemed authoritative if any item in
this table is ambiguous.
The conformance table is separated into various columns:
Feature - name of protocol feature (note that the indenting
indicates a hierarchy of conformance, i.e., the
conformance of a lower feature is only relevant if there
is conformance to the higher feature)
Section - reference section in main text of this document
Area - conformance area to which each feature applies:
C - content
T - transport
Status - whether the feature is mandatory, optional, or prohibited.
The key words used in this table are to be interpreted as described
in [REQ], though the following list gives a quick overview of the
different degrees of feature conformance:
Must - mandatory
Should - required in the absence of a compelling
need to omit.
May - optional
Should not - prohibited in the absence of a compelling
need.
Must not - prohibited
Footnote - special comment about conformance for a particular feature
Vaudreuil & Parsons Standards Track [Page 37]
RFC 3801 VPIMv2 June 2004
VPIM version 2 Conformance
| | | | |S| |
| | | | | |H| |F
| | | | | |O|M|o
| | | |S| |U|U|o
| | | |H| |L|S|t
| |A|M|O| |D|T|n
| |R|U|U|M| | |o
| |E|S|L|A|N|N|t
| |A|T|D|Y|O|O|t
FEATURE |SECTION | | | | |T|T|e
-------------------------------------------|----------|-|-|-|-|-|-|-
| | | | | | | |
Message Addressing Formats: | | | | | | | |
Use DNS host names |4.1 |C|x| | | | |
Use only numbers in mailbox IDs |4.1.1 |C| |x| | | |
Numbers in mailbox IDs follow E.164 |4.1.1 |C| |x| | | |
Use alpha-numeric mailbox IDs |4.1.1 |C| | |x| | |
Support of postmaster@domain |4.1.2 |C|x| | | | |
Support of non-mail-user@domain |4.1.2 |C| |x| | | |
Support of distribution lists |4.1.3 |C| | |x| | |
| | | | | | | |
Message Header Fields: | | | | | | | |
Sending outbound messages | | | | | | | |
From |4.2.1 |C|x| | | | |
Addition of text name |4.2.1 |C| |x| | | |
Same value as MAIL FROM |4.2.1 |C| |x| | | |
To |4.2.2 |C| |x| | | |1
cc |4.2.3 |C| | |x| | |1
Date |4.2.4 |C|x| | | | |
Sender |4.2.5 |C| | |x| | |
Return-Path |4.2.6 |C| | | | |x|
Message-ID |4.2.7 |C|x| | | | |
Reply-To |4.2.8 |C| | | |x| |
Received |4.2.9 |C|x| | | | |
MIME Version: 1.0 (Voice 2.0) |4.2.10 |C| |x| | | |
Content-Type |4.2.11 |C|x| | | | |
Content-Transfer-Encoding |4.2.12 |C|x| | | | |
Sensitivity |4.2.13 |C| | |x| | |
Importance |4.2.14 |C| | |x| | |
Subject |4.2.15 |C| |x| | | |
Disposition-notification-to |4.7 |C| |x| | | |
Other Headers |4.2 |C| | |x| | |
| | | | | | | |
Vaudreuil & Parsons Standards Track [Page 38]
RFC 3801 VPIMv2 June 2004
| | | | | |H| |F
| | | | | |O|M|o
| | | |S| |U|U|o
| | | |H| |L|S|t
| |A|M|O| |D|T|n
| |R|U|U|M| | |o
| |E|S|L|A|N|N|t
| |A|T|D|Y|O|O|t
FEATURE |SECTION | | | | |T|T|e
-------------------------------------------|----------|-|-|-|-|-|-|-
Receiving inbound messages | | | | | | | |
From |4.2.1 |C|x| | | | |
Present text personal name |4.2.1 |C| | |x| | |
To |4.2.2 |C|x| | | | |
cc |4.2.3 |C| | |x| | |
Date |4.2.4 |C|x| | | | |
Conversion of Date to local time |4.2.4 |C| |x| | | |
Sender |4.2.5 |C| | |x| | |
Return-Path |4.2.6 |C| |x| | | |
Message-ID |4.2.7 |C| | |x| | |
MDN requested |4.2.7 |C|x| | | | |
Reply-To |4.2.8 |C| | |x| | |
Received |4.2.9 |C| | |x| | |
MIME Version: 1.0 (Voice 2.0) |4.2.10 |C| |x| | | |
Content Type |4.2.11 |C|x| | | | |
Content-Transfer-Encoding |4.2.12 |C|x| | | | |
Sensitivity |4.2.13 |C|x| | | | |2
Importance |4.2.14 |C| | |x| | |
Subject |4.2.15 |C| | |x| | |
Disposition-notification-to |4.7 |C| |x| | | |
Other Headers |4.2 |C|x| | | | |3
| | | | | | | |
Message Content Encoding: | | | | | | | |
Sending outbound audio/fax contents | | | | | | | |
7BIT |4.2.12 |C| | | | |x|
8BIT |4.2.12 |C| | | | |x|
Quoted Printable |4.2.12 |C| | | | |x|
Base64 |4.2.12 |C|x| | | | |4
Binary |4.2.12 |C| |x| | | |5
Receiving inbound message contents | | | | | | | |
7BIT |4.2.12 |C|x| | | | |
8BIT |4.2.12 |C|x| | | | |
Quoted Printable |4.2.12 |C|x| | | | |
Base64 |4.2.12 |C|x| | | | |
Binary |4.2.12 |C|x| | | | |5
| | | | | | | |
Vaudreuil & Parsons Standards Track [Page 39]
RFC 3801 VPIMv2 June 2004
| | | | |S| |
| | | | | |H| |F
| | | | | |O|M|o
| | | |S| |U|U|o
| | | |H| |L|S|t
| |A|M|O| |D|T|n
| |R|U|U|M| | |o
| |E|S|L|A|N|N|t
| |A|T|D|Y|O|O|t
FEATURE |SECTION | | | | |T|T|e
-------------------------------------------|----------|-|-|-|-|-|-|-
Message Content Types: | | | | | | | |
Sending outbound messages | | | | | | | |
Multipart/Voice-Message |4.4.1 |C|x| | | | |
Message/RFC822 |4.4.2 |C| |x| | | |
Audio/32KADPCM |4.4.3 |C|x| | | | |
Content-Description |4.3.1 |C| | |x| | |
Content-Disposition |4.3.2 |C|x| | | | |
Content-Duration |4.3.3 |C| | |x| | |
Content-Language |4.3.4 |C| | |x| | |
Image/TIFF; application=faxbw |4.4.4 |C|x| | | | |7
Text/Directory |4.5.2 |C| | | |x| |9
Text/plain |4.5.4 |C| | | |x| |
Audio/* or Image/* (other encodings) |4.5.3 |C| | | |x| |
Other contents |4.5 |C| | | | |x|
Multipart/Mixed |4.5.1 |C| | |x| | |
Text/plain |4.5.4 |C| | |x| | |
Multipart/Report |4.6, 4.7 |C|x| | | | |
human-readable part is voice |4.6, 4.7 |C| |x| | | |
human-readable part is text |4.6, 4.7 |C| | |x| | |
Message/Delivery-Status |4.6 |C|x| | | | |
Message/Disposition-Notification |4.7 |C| |x| | | |
Other contents |4.5 |C| | | |x| |6
Receiving in inbound messages | | | | | | | |
Multipart/Voice-Message |4.4.1 |C|x| | | | |
Message/RFC822 |4.4.2 |C|x| | | | |
Audio/32KADPCM |4.4.3 |C|x| | | | |
Content-Description |4.3.1 |C| | |x| | |
Content-Disposition |4.3.2 |C| |x| | | |
Content-Duration |4.3.3 |C| | |x| | |
Content-Language |4.3.4 |C| | |x| | |
Image/TIFF; application=faxbw |4.4.4 |C| |x| | | |8
Text/Directory |4.5.2 |C|x| | | | |9
Text/plain |4.5.4 |C| | |x| | |
Audio/* or Image/* (other encodings) |4.5.3 |C| | |x| | |
Other contents |4.5 |C| | |x| | |
Multipart/Mixed |4.5.1 |C| | |x| | |
Vaudreuil & Parsons Standards Track [Page 40]
RFC 3801 VPIMv2 June 2004
| | | | | |S| |
| | | | | |H| |F
| | | | | |O|M|o
| | | |S| |U|U|o
| | | |H| |L|S|t
| |A|M|O| |D|T|n
| |R|U|U|M| | |o
| |E|S|L|A|N|N|t
| |A|T|D|Y|O|O|t
FEATURE |SECTION | | | | |T|T|e
------------------------------------------|-----------|-|-|-|-|-|-|-
| | | | | | | |
Text/plain |4.5.4 |C|x| | | | |
Multipart/Report |4.6, 4.7 |C|x| | | | |
human-readable part is voice |4.6, 4.7 |C|x| | | | |
human-readable part is text |4.6, 4.7 |C|x| | | | |
Message/Delivery-Status |4.6 |C|x| | | | |
Message/Disposition-Notification |4.7 |C| |x| | | |
Other contents |4.5 |C| | |x| | |6
| | | | | | | |
Forwarded Messages | | | | | | | |
use Message/RFC822 construct |4.8 |C| |x| | | |
simulate headers if none available |4.8 |C| |x| | | |
| | | | | | | |
Reply Messages |4.9 |C|x| | | | |
send to Reply-To, else From address |4.2.8 |C| | |x| | |
send to non-mail-user |4.9 |C| | | |x| |
| | | | | | | |
Notifications | | | | | | | |
use Multipart/Report format |4.6, 4.7 |C|x| | | | |
always send error on non-delivery |4.6 |C|x| | | | |
send error messages to return-path |4.2.6 |C|x| | | | |
| | | | | | | |
Message Transport Protocol: | | | | | | | |
Base ESMTP Commands | | | | | | | |
HELO |5.1 |T|x| | | | |
MAIL FROM |5.1 |T|x| | | | |
RCPT TO |5.1 |T|x| | | | |
DATA |5.1 |T|x| | | | |
TURN |5.1 |T| | | | |x|
QUIT |5.1 |T|x| | | | |
RSET |5.1 |T|x| | | | |
VRFY |5.1 |T| | |x| | |
EHLO |5.1 |T|x| | | | |
BDAT |5.1 |T| | |x| | |5
Vaudreuil & Parsons Standards Track [Page 41]
RFC 3801 VPIMv2 June 2004
| | | | |S| |
| | | | | |H| |F
| | | | | |O|M|o
| | | |S| |U|U|o
| | | |H| |L|S|t
| |A|M|O| |D|T|n
| |R|U|U|M| | |o
| |E|S|L|A|N|N|t
| |A|T|D|Y|O|O|t
FEATURE |SECTION | | | | |T|T|e
-------------------------------------------|----------|-|-|-|-|-|-|-
| | | | | | | |
ESMTP Keywords & Parameters | | | | | | | |
DSN |5.2.1 |T|x| | | | |
NOTIFY |5.2.1 |T|x| | | | |
RET |5.2.1 |T| |x| | | |
ENVID |5.2.1 |T| | |x| | |
ORCPT |5.2.1 |T| | |x| | |
SIZE |5.2.2 |T|x| | | | |
ENHANCEDSTATUSCODES |5.2.3 |T| |x| | | |
PIPELINING |5.2.4 |T| |x| | | |
CHUNKING |5.2.5 |T| | |x| | |
BINARYMIME |5.2.6 |T| | |x| | |
| | | | | | | |
ESMTP-SMTP Downgrading | | | | | | | |
send delivery report upon downgrade |5.3 |T|x| | | | |
| | | | | | | |
Directory Address Resolution | | | | | | | |
provide facility to resolve addresses |6 |C| |x| | | |
use headers to populate local directory |6 |C| | |x| | |
| | | | | | | |
Management Protocols: | | | | | | | |
Network management |7.1 |T| | |x| | |
-------------------------------------------|----------|-|-|-|-|-|-|-
Footnotes:
1. SHOULD leave blank if all recipients are not known or resolvable.
2. If a sensitive message is received by a system that does not
support sensitivity, then it MUST be returned to the originator
with an appropriate error notification. Also, a received
sensitive message MUST NOT be forwarded to anyone.
3. If the additional header fields are not understood they MAY
be ignored.
4. When binary transport is not available.
5. When binary transport is available.
Vaudreuil & Parsons Standards Track [Page 42]
RFC 3801 VPIMv2 June 2004
6. Other un-profiled contents MUST only be sent by bilateral
agreement.
7. If fax is supported.
8. If the fax content cannot be presented it MAY be dropped.
9. Handling of a vCard in text/directory is no longer defined.
13. Appendix B - Example Voice Messages
The following message is a full-featured message addressed to two
recipients. The message includes the sender's spoken name, spoken
subject and a short speech segment. The message is marked as
important and private.
To: +19725551212@vm1.mycompany.com
To: +16135551234@VM1.mycompany.com
From: "Parsons, Glenn" <12145551234@VM2.mycompany.com>
Date: Mon, 26 Aug 93 10:20:20 -0700 (CDT)
MIME-Version: 1.0 (Voice 2.0)
Content-type: Multipart/Voice-Message; Version=2.0;
Boundary="MessageBoundary"
Content-Transfer-Encoding: 7bit
Message-ID: 123456789@VM2.mycompany.com
Sensitivity: Private
Importance: High
Vaudreuil & Parsons Standards Track [Page 43]
RFC 3801 VPIMv2 June 2004
--MessageBoundary
Content-type: Audio/32KADPCM
Content-Transfer-Encoding: Base64
Content-Disposition: inline; voice=Originator-Spoken-Name
Content-Language: en-US
Content-ID: part1@VM2-4321
glslfdslsertiflkTfpgkTportrpkTpfgTpoiTpdadasssdasddasdasd
(This is a sample of the base-64 Spoken Name data)
fgdhgddlkgpokpeowrit09==
--MessageBoundary
Content-type: Audio/32KADPCM
Content-Transfer-Encoding: Base64
Content-Disposition: inline; voice=Spoken-Subject
Content-Language: en-US
Content-ID: part2@VM2-4321
glslfdslsertiflkTfpgkTportrpkTpfgTpoiTpdadasssdasddasdasd
(This is a sample of the base-64 Spoken Subject data)
fgdhgddlkgpokpeowrit09==
--MessageBoundary
Content-type: Audio/32KADPCM
Content-Transfer-Encoding: Base64
Content-Description: Brand X Voice Message
Content-Disposition: inline; voice=Voice-Message; filename=msg1.726
Content-Duration: 25
iIiIiIjMzN3czdze3s7d7fwfHhcvESJVe/4yEhLz8/FOQjVFRERCESL/zqrq
(This is a sample of the base64 message data) zb8tFdLTQt1PXj
u7wjOyRhws+krdns7Rju0t4tLF7cE0K0MxOTOnRW/Pn30c8uHi9==
--MessageBoundary- - - -
The following message is a forwarded single segment voice. Both the
forwarded message and the forwarding message contain the senders spoken
names.
To: +12145551212@vm1.mycompany.com
From: "Vaudreuil, Greg" <+19725552345@VM2.mycompany.com>
Date: Mon, 26 Aug 93 10:20:20 -0700 (CDT)
MIME-Version: 1.0 (Voice 2.0)
Content-type: Multipart/Voice-Message; Version=2.0;
Boundary="MessageBoundary"
Content-Transfer-Encoding: 7bit
Message-ID: ABCD-123456789@VM2.mycompany.com
Vaudreuil & Parsons Standards Track [Page 44]
RFC 3801 VPIMv2 June 2004
--MessageBoundary
Content-type: Audio/32KADPCM
Content-Transfer-Encoding: Base64
Content-Disposition: inline; voice=Originator-Spoken-Name
Content-Language: en-US
Content-ID: part3@VM2-4321
glslfdslsertiflkTfpgkTportrpkTpfgTpoiTpdadasssdasddasdasd
(This is a sample of the base-64 Spoken Name data)
fgdhgd dlkgpokpeowrit09==
--MessageBoundary
Content-type: Audio/32KADPCM
Content-Description: Forwarded Message Annotation
Content-Disposition: inline; voice=Voice-Message
Content-Transfer-Encoding: Base64
glslfdslsertiflkTfpgkTportrpkTpfgTpoiTpdadasssdasddasdasd
(This is the voiced introductory remarks encoded in base64)
jrgoij3o45itj09fiuvdkjgWlakgQ93ijkpokfpgokQ90gQ5tkjpokfgW
dlkgpokpeowrit09==
Vaudreuil & Parsons Standards Track [Page 45]
RFC 3801 VPIMv2 June 2004
--MessageBoundary
Content-type: Message/RFC822
Content-Transfer-Encoding: 7bit
To: +19725552345@VM2.mycompany.com
From: "Parsons, Glenn, W." <+16135551234@VM1.mycompany.com>
Date: Mon, 26 Aug 93 8:23:10 -0500 (EST)
Content-type: Multipart/Voice-Message; Version=2.0;
Boundary="MessageBoundary2"
Content-Transfer-Encoding: 7bit
MIME-Version: 1.0 (Voice 2.0)
--MessageBoundary2
Content-type: Audio/32KADPCM
Content-Transfer-Encoding: Base64
Content-Disposition: inline; voice=Originator-Spoken-Name
Content-Language: en-US
Content-ID: part6@VM2-4321
glslfdslsertiflkTfpgkTportrpkTpfgTpoiTpdadasssdasddasdasd
(This is a sample of the base-64 Spoken Name data) fgdhgd
dlkgpokpeowrit09==
--MessageBoundary2
Content-type: Audio/32KADPCM
Content-Disposition: inline; voice=Voice-Message
Content-Transfer-Encoding: Base64
glslfdslsertiflkTfpgkTportrpkTpfgTpoiTpdadasssdasddasdasd
(This is the original message audio data) fgwersdfmniwrjj
jrgoij3o45itj09fiuvdkjgWlakgQ93ijkpokfpgokQ90gQ5tkjpokfgW
dlkgpokpeowrit09==
--MessageBoundary2--
--MessageBoundary--
Vaudreuil & Parsons Standards Track [Page 46]
RFC 3801 VPIMv2 June 2004
The following example is for a DSN sent to the sender of a message by
a VPIM gateway at VM1.company.com for a mailbox which does not exist.
Date: Thu, 7 Jul 1994 17:16:05 -0400
From: Mail Delivery Subsystem <MAILER-DAEMON@vm.company.com>
Message-ID: <199407072116.RAA14128@vm1.company.com>
Subject: Returned voice message
To: 2175552345@VM2.mycompany.com
MIME-Version: 1.0
Content-Type: multipart/report; report-type=delivery-status;
boundary="RAA14128.773615765/VM1.COMPANY.COM"
--RAA14128.773615765/VM1.COMPANY.COM
Content-type: Audio/32KADPCM
Content-Description: Spoken Delivery Status Notification
Content-Disposition: inline; voice= Voice-Message-Notification
Content-Transfer-Encoding: Base64
glslfdslsertiflkTfpgkTportrpkTpfgTpoiTpdadadffsssddasdasd
(This is a voiced description of the error in base64)
jrgoij3o45itj09fiuvdkjgWlakgQ93ijkpokfpgokQ90gdffkjpokfgW
dlkgpokpeowrit09==
--RAA14128.773615765/VM1.COMPANY.COM
Content-type: Message/Delivery-Status
Reporting-MTA: dns; vm1.company.com
Original-Recipient: rfc822; 2145551234@VM1.mycompany.com
Final-Recipient: rfc822; 2145551234@VM1.mycompany.com
Action: failed
Status: 5.1.1 (User does not exist)
Diagnostic-Code: smtp; 550 Mailbox not found
Last-Attempt-Date: Thu, 7 Jul 1994 17:15:49 -0400
Vaudreuil & Parsons Standards Track [Page 47]
RFC 3801 VPIMv2 June 2004
--RAA14128.773615765/VM1.COMPANY.COM
content-type: Message/RFC822
[original VPIM message goes here]
--RAA14128.773615765/VM1.COMPANY.COM--
The following example is for an MDN sent to the original sender for a
message that has been played. This delivered VPIM message was
received by a corporate gateway and relayed to a unified mailbox.
Date: Thu, 7 Jul 1994 17:16:05 -0400
From: "Greg Vaudreuil" <22722@vm.company.com>
Message-ID: <199407072116.RAA14128@exchange.company.com>
Subject: Voice message played
To: 2175552345@VM2.mycompany.com
MIME-Version: 1.0
Content-Type: multipart/report;
Report-type=disposition-notification;
Boundary="RAA14128.773615765/EXCHANGE.COMPANY.COM"
--RAA14128.773615765/EXCHANGE.COMPANY.COM
Content-type: Audio/32KADPCM
Content-Description: Spoken Disposition Notification
Content-Disposition: inline; voice= Voice-Message-Notification
Content-Transfer-Encoding: Base64
glslfdslsertiflkTfpgkTportrpkTpfgTpoiTpdadadffsssddasdasd
(Voiced description of the disposition action in base64)
jrgoij3o45itj09fiuvdkjgWlakgQ93ijkpokfpgokQ90gdffkjpokfgW
dlkgpokpeowrit09==
--RAA14128.773615765/EXCHANGE.COMPANY.COM
Content-type: Message/Disposition-Notification
Reporting-UA: gregs-laptop.dallas.company.com (Unified FooMail 3.0)
Original-Recipient: rfc822;22722@vm.company.com
Final-Recipient: rfc822;Greg.Vaudreuil@foomail.company.com
Original-Message-ID: <199509192301.12345@vm2.mycompany.com>
Disposition: manual-action/MDN-sent-automatically; displayed
--RAA14128.773615765/EXCHANGE.COMPANY.COM
Content-type: Message/RFC822
[original VPIM message goes here]
--RAA14128.773615765/EXCHANGE.COMPANY.COM--
Vaudreuil & Parsons Standards Track [Page 48]
RFC 3801 VPIMv2 June 2004
14. Appendix C - Example Error Voice Processing Error Codes
The following common voice processing errors and their corresponding
status codes are given as examples. The text after the error codes
is intended only for reference to describe the error code.
Implementations should provide implementation-specific informative
comments after the error code rather than the text below.
Error condition RFC 1893 Error codes
----------------------------- --------------------------------
Analog delivery failed 4.4.1 Persistent connection error
because remote system is busy - busy
Analog delivery failed 4.4.1 Persistent protocol error
because remote system is - no answer from host
ring-no-answer
Remote system did not answer 5.5.5 Permanent protocol error
AMIS-Analog handshake ("D" in - wrong version
response to "C" at connect
time)
Mailbox does not exist 5.1.1 Permanent mailbox error
- does not exist
Mailbox full or over quota 4.2.2 Persistent mailbox error
- full
Disk full 4.3.1 Persistent system error
- full
Command out of sequence 5.5.1 Permanent protocol error
- invalid command
Frame Error 5.5.2 Permanent protocol error
- syntax error
Mailbox does not support FAX 5.6.1 Permanent media error
- not supported
Mailbox does not support TEXT 5.6.1 Permanent media error
- not supported
Sender is not authorized 5.7.1 Permanent security error
- sender not authorized
Vaudreuil & Parsons Standards Track [Page 49]
RFC 3801 VPIMv2 June 2004
Message marked private, but 5.3.3 Permanent system error
system is not private capable - not feature capable
15. Appendix D - Example Voice Processing Disposition Types
The following common voice processing disposition conditions and
their corresponding MDN Disposition (which contains the disposition
mode, type and modifier, if applicable) are given as examples.
Implementers should refer to [MDN] for a full description of the
format of message disposition notifications.
Notification event MDN Disposition mode, type & modifier
------------------------------ ------------------------------------
Message played by recipient, manual-action/MDN-sent-automatically;
receipt automatically returned displayed
Message deleted from mailbox manual-action/MDN-sent-automatically;
by user without listening deleted
Message cleared when mailbox manual-action/MDN-sent-automatically;
deleted by admin deleted/mailbox-terminated
Message automatically deleted automatic-action/
when older than administrator MDN-sent-automatically; deleted/
set threshold expired
Message processed, however manual-action/MDN-sent-automatically;
audio encoding unknown - processed/error
unable to play to user Error: unknown audio encoding
16. Appendix E - IANA Registrations
There are no changes to the registration per [DISP] of the voice
content disposition parameter defined in the earlier VPIM V2
document, RFC 2421. There are no changes to the registration per
[MIME4] of the Multipart/voice-message content type defines in the
earlier VPIM v2 document, RFC 2423.
Both are presented here for information.
Vaudreuil & Parsons Standards Track [Page 50]
RFC 3801 VPIMv2 June 2004
16.1. Voice Content-Disposition Parameter Definition
To: IANA@IANA.ORG
Subject: Registration of new Content-Disposition parameter
Content-Disposition parameter name: voice
Allowable values for this parameter:
Voice-Message - the primary voice message,
Voice-Message-Notification - a spoken delivery notification
or spoken disposition notification,
Originator-Spoken-Name - the spoken name of the originator,
Recipient-Spoken-Name - the spoken name of the recipient if
available to the originator and present if there is ONLY one
recipient,
Spoken-Subject- the spoken subject of the message, typically
spoken by the originator
Description:
In order to distinguish between the various types of audio contents
in a VPIM voice message a new disposition parameter "voice" is
defined with the preceding values to be used as appropriate. Note
that there SHOULD only be one instance of each of these types of
audio contents per message level. Additional instances of a given
type (i.e., parameter value) may occur within an attached forwarded
voice message.
16.2. Multipart/Voice-Message MIME Media Type Definition
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]
Vaudreuil & Parsons Standards Track [Page 51]
RFC 3801 VPIMv2 June 2004
The version parameter that contains the value "2.0" if
enclosed content conforms to [VPIM2R2]. 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
Applications that use this media type:
Primarily voice messaging
Additional information:
Magic number(s): none
File extension(s): .VPM
Macintosh File Type Code(s): VPIM
Person & email address to contact for further information:
Glenn W. Parsons
gparsons@nortelnetworks.com
Gregory M. Vaudreuil
gregv@ieee.org
Intended usage: COMMON
Vaudreuil & Parsons Standards Track [Page 52]
RFC 3801 VPIMv2 June 2004
Author/Change controller:
Glenn W. Parsons & Gregory M. Vaudreuil
17. Appendix F - Change History: RFC 2421 (VPIM V2) to this Document
The updated profile in this document is based on the implementation
and operational deployment experience of several vendors. The
changes are categorized as general, content, transport and
conformance. They are summarized below:
1. General
- Various and substantial editorial updates to improve
readability.
- Separated send rules from receive rules to aid clarity.
- Clarified the behavior upon reception of unrecognized content
types expected with the interworking between voice and unified
messaging systems. (E.g., Unsupported non-audio contents should
be discarded to deliver the audio message.)
- Reworked the sensitivity requirements to align them with X.400.
Eliminated dependencies upon the MIXER documents.
- Reorganized the content-type descriptions for clarity
2. Content
- Changed handling of received lines by a gateway to SHOULD NOT
delete in a gateway. In gateways to systems such as AMIS, it is
not possible to preserve this information. It is intended that
such systems be able to claim conformance.
- Eliminated the vCard as a supported VPIM V2 content type.
- Merged in text from RFC 2423 (Multipart/voice-message)
3. Transport
- None
4. Conformance
- Aligned the table of Appendix A to the requirements in the text.
Vaudreuil & Parsons Standards Track [Page 53]
RFC 3801 VPIMv2 June 2004
18. Authors' Addresses
Gregory M. Vaudreuil
Lucent Technologies
7291 Williamson Rd
Dallas, TX 75214
United States
EMail: gregv@ieee.org
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
Vaudreuil & Parsons Standards Track [Page 54]
RFC 3801 VPIMv2 June 2004
19. Full Copyright Statement
Copyright (C) The Internet Society (2004). This document is subject
to the rights, licenses and restrictions contained in BCP 78, and
except as set forth therein, the authors retain all their rights.
This document and the information contained herein are provided on an
"AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS
OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY AND THE INTERNET
ENGINEERING TASK FORCE DISCLAIM 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.
Intellectual Property
The IETF takes no position regarding the validity or scope of any
Intellectual Property Rights or other rights that might be claimed to
pertain to the implementation or use of the technology described in
this document or the extent to which any license under such rights
might or might not be available; nor does it represent that it has
made any independent effort to identify any such rights. Information
on the procedures with respect to rights in RFC documents can be
found in BCP 78 and BCP 79.
Copies of IPR disclosures made to the IETF Secretariat and any
assurances of licenses to be made available, or the result of an
attempt made to obtain a general license or permission for the use of
such proprietary rights by implementers or users of this
specification can be obtained from the IETF on-line IPR repository at
http://www.ietf.org/ipr.
The IETF invites any interested party to bring to its attention any
copyrights, patents or patent applications, or other proprietary
rights that may cover technology that may be required to implement
this standard. Please address the information to the IETF at ietf-
ipr@ietf.org.
Acknowledgement
Funding for the RFC Editor function is currently provided by the
Internet Society.
Vaudreuil & Parsons Standards Track [Page 55]