Network Working Group Greg Vaudreuil
Internet Draft Octel Network Services
Expires: May 1, 1995 January 26, 1995
MIME/ESMTP Profile for
Voice Messaging
<draft-umig-mime-voice-01.txt>
Changes From the previous version
1) A large number of textual clarifications were made, including
discussion of X.440.
2) The reference section was updated.
3) Examples were fixed to reflect the current text.
Status of this Memo
This document is an Internet Draft. Internet Drafts are working
documents of the Internet Engineering Task Force (IETF), its
Areas, and its Working Groups. Note that other groups may also
distribute working documents as Internet Drafts.
Internet Drafts are valid for a maximum of six months and may be
updated, replaced, or obsoleted by other documents at any time.
It is inappropriate to use Internet Drafts as reference material
or to cite them other than as a "work in progress".
1.Abstract
A class of special-purpose computers has evolved to provide voice
messaging services. These machines generally interface to a
telephone switch and provide call answering and voice messaging
services. Traditionally, messages sent to a non-local machine
are transported using analog networking protocols based on DTMF
signaling and analog voice playback. As the demand for
networking increases, there is a need for a standard high-quality
digital protocol to connect these machines. The following
document is a profile of the Internet standard MIME and ESMTP
protocols for use as a digital voice networking protocol.
This profile is based on an earlier effort in the Audio Message
Interchange Specification (AMIS) group to define a voice
messaging protocol based on X.400 technology. This protocol is
intended to satisfy the user requirements statement from that
earlier work with the industry standard ESMTP/MIME mail protocol
infrastructures already used within corporate internets. This
profile will be called the voice profile in this document.
Internet Draft MIME Voice Profile January 26, 1995
2.Scope and Design Goals
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
including voice and facsimile.
It is not a goal to make interoperability possible between the
earlier X.400-based AMIS-Digital and this profile using a
standard X.400-to-MIME gateway. While the message encodings and
messages semantics are similar, the addressing and routing are
not. The X.400-based AMIS-Digital addressing format is
sufficiently customized so that it cannot be mapped to the RFC
822 mail format in the standard manner. The voice profile is
necessarily incompatible because it is intended to use the
standard TCP/IP mail addressing formats.
Because the 1988 X.400 based X.440 does not restrict the range of
addressing possible in X.400, translation to this protocol should
be possible using the standard X.400 to MIME gateway.
It is a goal of this effort to make as few changes to the
existing Internet mail protocols as possible while satisfying the
user requirements for Voice Networking. 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.
While it is possible to use these protocols for simple point-to-
point networking, the specification is robust enough to be used
in an environment such as the global Internet with installed base
gateways which do not understand MIME. It is expected that a
messaging system will be managed by a system administrator who
can perform TCP/IP network configuration. When using facsimile
or multiple voice encodings, it is expected that the system
administrator will maintain a list of the capabilities of the
networked mail machines to reduce the sending of undeliverable
messages due to lack of feature support.
This specification is a profile of the relevant TCP/IP Internet
protocols. These technologies, as well as the specifications for
the Internet mail protocols, are defined in the Request for
Comment (RFC) document series. That series documents the
standards as well as the lore of the TCP/IP protocol suite. This
document should be read with the following RFC documents: RFC
821, the Simple Mail Transport Protocol; RFC 822, the Standard
for the format of ARPA Internet Messages; RFC 1521 and RFC 1522,
the Multipurpose Internet Mail Extensions; RFC 1425 and RFC 1427,
Extensions to the SMTP protocol (ESMTP); and RFC 882 and RFC 883,
the Domain Name System. Where additional functionality is
needed, it will be defined in this document or in an appendix.
Vaudreuil Expires 5/1/95 ]
Internet Draft MIME Voice Profile January 26, 1995
3.Protocol Restrictions
This protocol does not limit the number of recipients per
message. Where possible, implementations should not restrict the
number of recipients in a single message.
Recognising that no implementation supports unlimited
recipients, and that the number of supported recipients may
be quite low, ESMTP should be extended to provide a
mechanism for indicating the number of supported recipients.
This protocol does not limit the maximum message length.
Implementors should understand that some machines will be unable
to accept excessively long messages. A mechanism is defined in
the RFC 1425 ESMTP extensions to declare the maximum message size
supported.
The message size indicatd in the ESMTP SIZE command is in
bytes, not minutes. The number of bytes varies by voice
encoding format and must include the MIME wrapper overhead.
Translation into minutes, can be performed by simple
multiplication if the voice encoding is know from the system
configuration file.
Framework for the voice profile
This document specifies a profile of the TCP/IP multimedia
messaging protocols for use by special-purpose voice processing
platforms. These platforms are not general-purpose computers and
often do not have facilities normally associated with an Internet
Email-capable computer.
The following are typical restrictions imposed by a voice
messaging platform:
1) Text messages are not normally received and often cannot be
displayed or viewed in the normal fashion. They can be
processed only via advanced text-to-speech or text-to-fax
features not currently present in these machines.
Voice mail (VM) machines act as an integr
Transfer Agent and a User Agent. The VM is responsible for
final delivery, and there is no forwarding of messages. RFC
822 header fields have limited use in the context of the
simple messaging features currently deployed.
3) VM message stores are generally not capable of preserving the
full semantics of an Internet message. As such, use of a VM
for general message forwarding and gatewaying is not
supported. Storage of "Received" lines and "Message-ID" may
be limited.
Nothing in this document precludes use of a general purpose
email gateway from providing these services. However, severe
Vaudreuil Expires 5/1/95 3]
Internet Draft MIME Voice Profile January 26, 1995
performance degradation may result if the email gateway does
not support the advanced ESMTP options required by this
document.
Internet-style mailing lists are not generally supported.
Distribution lists are implemented as local alias lists.
5) There is generally no human operator. Error reports must be
machine-parsable so that helpful responses can be given to
users whose only access mechanism is a telephone.
The system user names are limited to 16 or fewer numeric
characters.
Vaudreuil Expires 5/1/95 ]
Internet Draft MIME Voice Profile January 26, 1995
5.Message Format Profile
The voice profile was written to be based on and be consistent
with the TCP/IP Email Protocol Suite with newly standardized
options for enhanced functionality and performance. This section
is an overview of the necessary protocols and a profile of the
applicable protocols as applied to the voice messaging
environment.
5.1. Message Addressing Formats
RFC 822 and SMTP addressing uses 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
machine or node identification. These two components are
separated by the commercial "@" symbol.
The local part of the address is an ASCII string uniquely
identifying a mailbox on a destination system. The local part is
a printable string containing the mailbox number of the
originator or a recipient. Administration of this number space
is expected to be conform to national or corporate private
telephone numbering plans.
The domain part of the address is a hierarchical global name for
all machines. For participation in the international Internet
network or for integration within a corporate internet, each VM
machine is required to have a unique domain name. In the domain
name system, a name is registered with the Internet Assigned
Number Authority (IANA). The IANA may delegate the management of
a branch of the naming space to a company or service provider.
For example, a compliant message may contain the address
2145551212@mycompany.com. It should be noted that while the
example mailbox address is based on the North American Numbering
Plan, any other corporate numbering plan can be used. The use of
the domain naming system should be transparent to the user. It
is the responsibility of the VM to translate the dialed address
to the fully-qualified domain name (FQDN). The mapping of dialed
address to VM destination is generally accomplished through
implementation-specific means, usually a local table.
Mapping of the FQDN to a specific network destination is
generally performed by the Domain Name System. For networks with
a small number of machines, a locally-maintained host table
database can be used as a simpler alternative.
Special addresses are provided for compatibility with the
conventions of the Internet mail system and to facilitate
testing. These addresses do not use numeric local addresses,
both to conform to current Internet practice and to avoid
conflict with existing numeric addressing plans. Some special
addresses are as follows:
Vaudreuil Expires 5/1/95 ]
Internet Draft MIME Voice Profile January 26, 1995
Postmaster@domain
By convention, a special mailbox named "postmaster"
should 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 a individual
implementation choice.
Loopback@domain
A special mailbox name named "loopback" should be
designated for loopback testing. All messages sent
to this mailbox must be returned back to the sender
as a new message. The originating address should be
"postmaster".
Because VMs do not use alpha-numeric addresses, this
address will not conflict with any internal
numbering plan. Internal to VM, a specific numeric
address for DTMF entry can be mapped to "loopback".
Note that without network level authentication, the
loopback address can be abused by routing messages
through a third-party VM to spoof another device or
to avoid toll charges. It is recommended that the
loopback feature be disabled except when testing the
networking between machines.
5.2. 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, headers do not
indicate delivery options for the transport of messages.
RFC 822 defines a set of standard message header fields. This
set is extended in several RFCs.
Note that the specific order of header lines is not specified.
The order cannot be expected to be preserved when sent through
intermediate gateways. The following header fields must be
supported.
Network Working Group Greg Vaudreuil
Internet Draft Octel Network Services
Expires: May 1, 1995 January 26, 1995
MIME/ESMTP Profile for
Voice Messaging
<draft-umig-mime-voice-01.txt>
Changes From the previous version
1) A large number of textual clarifications were made, including discussion
of X.440.
2) The reference section was updated.
3) Examples were fixed to reflect the current text.
Status of this Memo
This document is an Internet Draft. Internet Drafts are working documents
of the Internet Engineering Task Force (IETF), its Areas, and its Working
Groups. Note that other groups may also distribute working documents as
Internet Drafts.
Internet Drafts are valid for a maximum of six months and may be updated,
replaced, or obsoleted by other documents at any time. It is inappropriate
to use Internet Drafts as reference material or to cite them other than as
a "work in progress".
1.Abstract
A class of special-purpose computers has evolved to provide voice messaging
services. These machines generally interface to a telephone switch and
provide call answering and voice messaging services. Traditionally,
messages sent to a non-local machine are transported using analog
networking protocols based on DTMF signaling and analog voice playback. As
the demand for networking increases, there is a need for a standard high-
quality digital protocol to connect these machines. The following document
is a profile of the Internet standard MIME and ESMTP protocols for use as a
digital voice networking protocol.
This profile is based on an earlier effort in the Audio Message Interchange
Specification (AMIS) group to define a voice messaging protocol based on
X.400 technology. This protocol is intended to satisfy the user
requirements statement from that earlier work with the industry standard
ESMTP/MIME mail protocol infrastructures already used within corporate
internets. This profile will be called the voice profile in this document.
2.Scope and Design Goals
MIME is the Internet multipurpose, multimedia messaging standard. This
document explicitly recognizes its capabilities and provides a mechanism
Internet Draft MIME Voice Profile January 26, 1995
for the exchange of various messaging technologies including voice and
facsimile.
It is not a goal to make interoperability possible between the earlier
X.400-based AMIS-Digital and this profile using a standard X.400-to-MIME
gateway. While the message encodings and messages semantics are similar,
the addressing and routing are not. The X.400-based AMIS-Digital
addressing format is sufficiently customized so that it cannot be mapped to
the RFC 822 mail format in the standard manner. The voice profile is
necessarily incompatible because it is intended to use the standard TCP/IP
mail addressing formats.
Because the 1988 X.400 based X.440 does not restrict the range of
addressing possible in X.400, translation to this protocol should be
possible using the standard X.400 to MIME gateway.
It is a goal of this effort to make as few changes to the existing
Internet mail protocols as possible while satisfying the user requirements
for Voice Networking. 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. While it is
possible to use these protocols for simple point-to-point networking, the
specification is robust enough to be used in an environment such as the
global Internet with installed base gateways which do not understand MIME.
It is expected that a messaging system will be managed by a system
administrator who can perform TCP/IP network configuration. When using
facsimile or multiple voice encodings, it is expected that the system
administrator will maintain a list of the capabilities of the networked
mail machines to reduce the sending of undeliverable messages due to lack
of feature support.
This specification is a profile of the relevant TCP/IP Internet protocols.
These technologies, as well as the specifications for the Internet mail
protocols, are defined in the Request for Comment (RFC) document series.
That series documents the standards as well as the lore of the TCP/IP
protocol suite. This document should be read with the following RFC
documents: RFC 821, the Simple Mail Transport Protocol; RFC 822, the
Standard for the format of ARPA Internet Messages; RFC 1521 and RFC 1522,
the Multipurpose Internet Mail Extensions; RFC 1425 and RFC 1427,
Extensions to the SMTP protocol (ESMTP); and RFC 882 and RFC 883, the
Domain Name System. Where additional functionality is needed, it will be
defined in this document or in an appendix.
3.Protocol Restrictions
This protocol does not limit the number of recipients per message. Where
possible, implementations should not restrict the number of recipients in a
single message.
Recognising that no implementation supports unlimited recipients, and
that the number of supported recipients may be quite low, ESMTP should
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Internet Draft MIME Voice Profile January 26, 1995
be extended to provide a mechanism for indicating the number of
supported recipients.
This protocol does not limit the maximum message length. Implementors
should understand that some machines will be unable to accept excessively
long messages. A mechanism is defined in the RFC 1425 ESMTP extensions to
declare the maximum message size supported.
The message size indicatd in the ESMTP SIZE command is in bytes, not
minutes. The number of bytes varies by voice encoding format and must
include the MIME wrapper overhead. Translation into minutes, can be
performed by simple multiplication if the voice encoding is know from
the system configuration file.
Framework for the voice profile
This document specifies a profile of the TCP/IP multimedia messaging
protocols for use by special-purpose voice processing platforms. These
platforms are not general-purpose computers and often do not have
facilities normally associated with an Internet Email-capable computer.
The following are typical restrictions imposed by a voice messaging
platform:
Text messages are not normally received and often cannot be displayed
or viewed in the normal fashion. They can be processed only via
advanced text-to-speech or text-to-fax features not currently present
in these machines.
2) Voice mail (VM) machines act as an integrated Message Transfer Agent
and a User Agent. The VM is responsible for final delivery, and there
is no forwarding of messages. RFC 822 header fields have limited use
in the context of the simple messaging features currently deployed.
3) VM message stores are generally not capable of preserving the full
semantics of an Internet message. As such, use of a VM for general
message forwarding and gatewaying is not supported. Storage of
"Received" lines and "Message-ID" may be limited.
Nothing in this document precludes use of a general purpose email
gateway from providing these services. However, severe performance
degradation may result if the email gateway does not support the
advanced ESMTP options required by this document.
4) Internet-style mailing lists are not generally supported. Distribution
lists are implemented as local alias lists.
There is generally no human operator. Error reports must be machine-
parsable so that helpful responses can be given to users whose only
access mechanism is a telephone.
The system user names are limited to 16 or fewer numeric characters.
Vaudreuil Expires 5/1/95 3]
Internet Draft MIME Voice Profile January 26, 1995
5.Message Format Profile
The voice profile was written to be based on and be consistent with the
TCP/IP Email Protocol Suite with newly standardized options for enhanced
functionality and performance. This section is an overview of the necessary
protocols and a profile of the applicable protocols as applied to the voice
messaging environment.
5.1. Message Addressing Formats
RFC 822 and SMTP addressing uses 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 machine or node identification.
These two components are separated by the commercial "@" symbol.
The local part of the address is an ASCII string uniquely identifying a
mailbox on a destination system. The local part is a printable string
containing the mailbox number of the originator or a recipient.
Administration of this number space is expected to be conform to national
or corporate private telephone numbering plans.
The domain part of the address is a hierarchical global name for all
machines. For participation in the international Internet network or for
integration within a corporate internet, each VM machine is required to
have a unique domain name. In the domain name system, a name is registered
with the Internet Assigned Number Authority (IANA). The IANA may delegate
the management of a branch of the naming space to a company or service
provider.
For example, a compliant message may contain the address
2145551212@mycompany.com. It should be noted that while the example mailbox
address is based on the North American Numbering Plan, any other corporate
numbering plan can be used. The use of the domain naming system should be
transparent to the user. It is the responsibility of the VM to translate
the dialed address to the fully-qualified domain name (FQDN). The mapping
of dialed address to VM destination is generally accomplished through
implementation-specific means, usually a local table.
Mapping of the FQDN to a specific network destination is generally
performed by the Domain Name System. For networks with a small number of
machines, a locally-maintained host table database can be used as a simpler
alternative.
Special addresses are provided for compatibility with the conventions of
the Internet mail system and to facilitate testing. These addresses do not
use numeric local addresses, both to conform to current Internet practice
and to avoid conflict with existing numeric addressing plans. Some special
addresses are as follows:
Postmaster@domain
By convention, a special mailbox named "postmaster" should
exist on all systems. This address is used for diagnostics
and should be checked regularly by the system manager. This
Vaudreuil es 5/1/95
Internet Draft MIME Voice Profile January 26, 1995
mailbox is particularly likely to receive text messages, which
is not normal on a voice processing platform; the specific
handling of these messages is a individual implementation
choice.
Loopback@domain
A special mailbox name named "loopback" should be designated
for loopback testing. All messages sent to this mailbox must
be returned back to the sender as a new message. The
originating address should be "postmaster".
Because VMs do not use alpha-numeric addresses, this address
will not conflict with any internal numbering plan. Internal
to VM, a specific numeric address for DTMF entry can be mapped
to "loopback".
Note that without network level authentication, the loopback
address can be abused by routing messages through a third-
party VM to spoof another device or to avoid toll charges. It
is recommended that the loopback feature be disabled except
when testing the networking between machines.
5.2. 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,
headers do not indicate delivery options for the transport of messages.
RFC 822 defines a set of standard message header fields. This set is
extended in several RFCs.
Note that the specific order of header lines is not specified. The order
cannot be expected to be preserved when sent through intermediate gateways.
The following header fields must be supported.
From
The originator's fully-qualified domain address (a mailbox
number followed by the fully-qualified domain name). The user
listed in this field should be presented in the voice message
envelope as the originator of the message.
It is recommended that all messages contain the text personal
name of the sender in a quoted phrase if available. From
[822]
Example:
From: "Joe S. User" <2145551212@mycompany.com>
To
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The recipient's fully-qualified domain address. There may be
one or more To: fields in any message. All recipients of a
message must be listed in To lines except when a recipient is
specifically intended to receive a blind carbon copy. Note
that many VM systems have no facilities for storing or
reporting to the recipient the list of recipients. These
systems will generally discard these headers when received.
It is recommended that all messages contain the text personal
name of the recipient in a quoted phrase if available. From
[822]
Cc
Additional recipients' fully-qualified domain address. This
field has no meaning beyond "To:" in a VM and is not to be
generated by a conforming implementation. It is included for
processing by the receiver for compatibility with general
Internet mail agents that may not restrict the use of this
field.
If the VM supports the reporting of multiple recipients, all
names in the To: and Cc: fields should be reported. From [822]
Date
The date, time, and time zone the message was composed by the
originator, or the time specified by the originator if the
message is scheduled for delayed delivery. Conforming
implementations must be able to convert RFC 822 date and time
stamps into local time. If the VM reports message-sent time,
the value in the Date field should be used, not the time the
message was received at the destination system. From [822]
Example: Wed, 28 Jul 93 10:08:49 PDT
Sender
The actual address of the originator if the message is sent by
an agent on behalf of the author indicated in the From: field.
This field is not to be generated by a conforming
implementation. It is included for processing by the receiver
for compatibility with general Internet mail software that may
generate this header.
The Sender field often contains the name of an Internet-style
mailing list administrator and is the destination address for
reporting errors if the ESMTP MAIL FROM address is not
available. While it may not be possible to save this
information in some VM machines, discarding this information
or the SMTP MAIL FROM address will make it difficult to send
an error message to the proper destination. From [822]
Message-id
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A unique per-message identifier. Conforming systems must use
an identifier constructed by concatenating a unique 8-digit
serial message number and the sending VM's FQDN with the
commercial @ symbol. This identifier will be used for
tracking, auditing, and returning delivery reports. From
[822]
Example:
Message-id: <12345678@mycompany.com>
Received
Special-purpose trace information added to the beginning of a
RFC 822 message by message transport agents (MTA). This is
the only header permitted to be added by an MTA. Information
in this header is useful for debugging when using an ASCII
message reader or a header parsing tool. A conforming system
must add Received headers when acting as a gateway and must
not remove them. These headers may be ignored or deleted when
the message is received at the final destination. From [822]
MIME Version
Indicates that the message is conformant to the MIME message
format specification. This header must be present in any
conforming message. Systems conformant to this profile will
include a comment with the words "(VOICE 1.0)". From [MIME]
Example:
MIME-Version: 1.0 (VOICE 1.0)
Content-Type
The content-type header declares the type of content enclosed
in the message. One of the allowable contents is multipart, a
mechanism for bundling several message components into a
single message. The allowable contents are specified in the
next section of this document. From [MIME]
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. From [MIME]
Sensitivity
The requested privacy level. If this field exists, regardless
of the selected case-insensitive value "Personal" or
"Private". If no privacy is requested, this field is omitted.
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If a Sensitivity header is present in the message, a
conformant system is prohibited from forwarding this message.
If the receiving system does not support privacy and the
sensitivity is one of "Personal" or "Private", the message
must be returned to the sender with an appropriate error
message indicating that privacy could not be assured and that
the message was not delivered.
The specific privacy values do not need to be offered
individually to users but can be set on a system-wide basis.
From [X400]
Importance
Indicates the requested priority to be given by the receiving
system. The case-insensitive values "low", "normal" and
"high" are specified. If no special importance is requested,
this header may be omitted and the value assumed to be
"normal". This field can be used to order messages in a
recipient's mailbox and is equivalent to the AMIS-Digital
Priority indication. From [X400]
5.3. Message Content Types
MIME is a general-purpose message body format that is extensible to carry a
wide range of body parts. The basic protocol is described in [MIME]. MIME
also provides for encoding binary data so that it can be transported over
the 7-bit text-oriented SMTP protocol. This transport encoding is
independent of the audio encoding designed 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 ("Base-64"). While Base-64
is dramatically more efficient for audio data, both will work. Where
binary transport is available, not transport encoding is needed, and the
data can be labled as "Binary".
An implementation in conformance with this profile is required to send
audio data in binary form when binary message transport is available. When
binary transport is not available, implementations must encode the message
as Base-64. The detection and decoding of "Quoted-Printable", "7bit", and
"8bit" must also be supported in order to meet MIME requirements and to
preserve interoperability with the fullest range of possible devices.
Bullet this list....
The following content types are identified for use with this profile. Note
that each of these contents can be sent individually in a message or
wrapped in a multipart message to send multi-segment messages.
Message/RFC822 (REQUIRED)
MIME requires support of the Message/RFC822 message
encapsulation body part. This body part is used in the
Internet to forward complete messages within a multipart/mixed
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Internet Draft MIME Voice Profile January 26, 1995
message. Processing of this body part entails trivial
processing to unencapsulate/encapsulate the message. It is
not to be sent by a system conformant to this profile but must
be accepted for conformance with basic MIME. From [MIME]
Text/Plain (REQUIRED)
MIME requires support of the basic text/plain content type.
This content type has no applicability within the voice
messaging environment and should not be sent. Specific
handling depends on the platform, and interpretation of this
content-type is left as an implementation decision. Options
include dropping the body part and sending a delivery report
indicating the lack of support, text-to-speech, and text-to-
fax support. From [MIME]
Multipart/Mixed (REQUIRED)
MIME provides the facilities for enclosing several body parts
in a single message. Multipart/Mixed may be used for sending
multi-segment voice messages, that is, to preserve across the
network the distinction between an annotation and a forwarded
message. Systems are permitted to collapse such a multi-
segment message into a single segment if multi-segment
messages are not supported on the receiving machine. From
[MIME]
Text/Signature (RECOMMENDED)
Text/Signature provides a mechanism for the sending of per-
user directory information including the spoken name and the
supported mailbox capabilities. When used with a caching
mechanism, basic directory services with entries for commonly
used entries can be maintained. This body part is intended to
be used to support spoken name confirmation. The
Text/Signature can be included with a message using the
multipart/mixed constructor type. From [SIG]
Message/Notification (REQUIRED)
This new MIME body part is used for sending machine parsable
delivery status notifications. From [NOTIFY]
Multipart/Report (REQUIRED)
The Multipart/Report is used for enclosing a
Message/Notification body part and any returned message
content. This body type is a companion to
Message/Notification. From [NOTIFY2]
Audio/ADPCM (REQUIRED)
CCITT Recommendation G.721 describes the algorithm recommended
for conversion of a 64 KB/s A-law or u-law PCM channel to and
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from a 32 KB/s channel. The conversion is applied to the PCM
stream using an Adaptive Differential Pulse Code Modulation
(ADPCM) transcoding technique. This algorithm will be
registered with the IANA for MIME use under the name
Audio/ADPCM.
Support of Audio/ADPCM is required for conformance with this
profile.
Proprietary Voice Formats (OPTIONAL)
Proprietary voice encoding formats are supported under this
profile provided a unique identifier is registered with the
IANA prior to use.
Note that use of proprietary encodings reduces
interoperability in the absence of explicit manual system
configuration.
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6. Message Transport Protocol
Messages are transported between VM machines using the Internet Extended
Simple Mail Transport 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 networking 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 traditionally been
transported by encoding the messages into a 7-bit text-like form. [ESMTP]
was recently published and formalized an extension mechanism for SMTP, and
subsequent RFCs have defined 8-bit text networking, binary networking, and
extensions to permit the declaration of message size for the efficient
transmission of large messages such as multi-minute voice mail.
A command streaming extension for high performance message transmission has
been defined. [PIPE] This extension reduces the number of round-trip
packet exchanges and makes it possible to validate all recipient addresses
in one operation. This extension is optional but recommended.
The following sections list ESMTP commands, keywords, and parameters that
are required and those that are optional.
6.1. ESMTP Commands
HELO (REQUIRED)
Base SMTP greeting and identification of sender. This command
is not to be sent by conforming systems unless the more-
capable EHLO command is not accepted. It is included for
compatibility with general SMTP implementations. From [SMTP]
MAIL FROM (REQUIRED)
Originating mailbox. This address contains the mailbox to
which errors should be sent. This address may not be the same
as the message sender listed in the message header fields if
the message was gatewayed or sent to an Internet-style mailing
list. From [SMTP]
RCPT TO (REQUIRED)
Recipient's mailbox. This field contains only the addresses
to which the message should be delivered for this transaction.
In the event that multiple transport connections to multiple
destination machines are required for the same message, this
list may not match the list of recipients in the message
header. From [SMTP]
DATA (REQUIRED)
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Initiates the transfer of message data. This command is
required to be supported but should only be used in the event
the binary mode command BDAT is not supported. From [SMTP]
TURN (RECOMMENDED)
Requests a change-of-roles, that is, the client that opened
the connection offers to assume the role of server for any
mail the remote machine may wish to send. This command is
useful to poll for messages.
(Note the security implications of using the turn command to
fetch mail queued for another destination. This fetching is
possible because of the lack of authentication of the sending
VM by the protocol). From [SMTP]
QUIT (REQUIRED)
Requests that the connection be closed. If accepted, the
remote machine will reset and close the connection. From
[SMTP]
RSET (REQUIRED)
Resets the connection to its initial state. From [SMTP]
VRFY (OPTIONAL)
Requests verification that this node can reach the listed
recipient. While this functionality is also included in the
RCPT TO command, VRFY allows the query without beginning a
mail transfer transaction. This command is useful for
debugging and tracing problems. From [SMTP]
(Note that the implementation of VRFY may simplify the
guessing of a recipient's mailbox or automated sweeps for
valid mailbox addresses, resulting in a possible reduction in
privacy. Various implementation techniques may be used to
reduce the threat, such as limiting the number of queries per
session.) From [SMTP]
EHLO (REQUIRED)
Enhanced mail greeting that enables a server to announce
support for extended messaging options. The extended
messaging modes are discussed in a later section of this
document. From [ESMTP]
BDAT (REQUIRED)
Initiates binary data transmission.
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The BDAT command is an alternative to the earlier DATA
command. The BDAT command does not require encoding voice
data into 7-bit line-limited formats.
All other commands must be recognized and an appropriate
error code returned if not supported. From [BIN]
6.2. ESMTP Keywords
STREAMING (Optional)
The "STREAMING" keyword indicates ability of the receiving
SMTP to accept pipelined SMTP commands. From [PIPE]
SIZE (Required)
The "SIZE" keyword provides a mechanism by which the receiving
SMTP can indicate the maximum size message supported. From
[SIZE]
CHUNKING (Required)
The "CHUNKING" keyword indicates that the receiver will
support the high-performance transport mode. Note that
CHUNKING can be used with any message format and does not
imply support for binary encoded messages. From [BIN]
BINARYMIME (Required)
The "BINARYMIME" keyword indicates that the receiver SMTP can
accept binary encoded MIME messages. Note that CHUNKING mode
must be supported for this option, but CHUNKING does not mean
that binary messages can be supported. From [BIN]
NOTIFY (Required)
The "NOTIFY" keywork indicates that the receiver SMTP will
accept explicit delivery status notification requests. From
[DSN]
6.3. ESMTP Parameters - MAIL FROM
BINARYMIME The current message is a binary encoded MIME messages. From
[BIN]
6.4. ESMTP Parameters - RCPT TO
NOTIFY The conditions under which a delivery report should be sent.
From [DSN]
RET Whether the content of the message should be returned. From
[DSN]
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7.Management Protocols
The Internet protocols provide a mechanism for the management of VM
machines, from the management of the physical network through the
management of the message queues. SNMP should be supported on a compliant
message machine.
The digital interface to the VM and the TCP/IP protocols should be managed
by the standard network Managed Information Bases (MIBs). MIB II provides
basic statistics and reporting of the TCP/IP protocol performance and
statistics. Media-specific MIBs are available for X.25, Ethernet, FDDI,
Token Ring, Frame Relay, and other network technologies. This MIB provides
necessary information to diagnose faulty hardware, overloaded network
conditions, and excessive traffic conditions from a remote management
station.
Management of the machine resources and message queue monitoring based on
the host MIB and the Message and Directory MIB is recommended but not
required for conformance with this profile.
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8.References
[MIME] Borenstein, N., and N. Freed, "Multipurpose Internet Mail
Extensions", RFC 1521, Bellcore, Innosoft, Sept 1993.
[MSG822] Crocker, D., "Standard for the Format of ARPA Internet Text
Messages", STD 11, RFC 822, UDEL, August 1982.
[X400] Hardcastle-Kille, S., "Mapping between X.400(1988) / ISO 10021
and RFC 822", RFC 1327, May 1992.
[PIPE] Freed, N., Klensin, J., "SMTP Service Extension for Command
Pipelining" Internet Draft <draft-freed-streaming-0?.txt>
[ESMTP] Klensin, J., Freed, N., Rose, M., Stefferud, E., and D. Crocker,
"SMTP Service Extensions" RFC 1425, United Nations University,
Innosoft International, Inc., Dover Beach Consulting, Inc.,
Network Management Associates, Inc., The Branch Office, February
1993.
[SIZE] Klensin, J, Freed, N., Moore, K, "SMTP Service Extensions for
Message Size Declaration" RFC 1427, United Nations University,
Innosoft International, Inc., Inc., February 1993. February 1993.
[8BIT] Klensin, J., Freed, N., Rose, M., Stefferud, E., D. Crocker,
"SMTP Service Extension for 8bit-MIMEtransport" RFC 1426, United
Nations University, Innosoft International, Inc., Dover Beach
Consulting, Inc., Network Management Associates, Inc., The Branch
Office, February 1993.
[DNS1] Mockapetris, P.,"Domain names - implementation and
specification", RFC1035, Nov 1987.
[DNS2] Mockapetris, P.,"Domain names - concepts and facilities", RFC
1034, Nov 1987.
[SMTP] Postel, J., "Simple Mail Transfer Protocol", STD 10, RFC 821,
USC/Information Sciences Institute, August 1982.
[SIG] Vaudreuil, G., "Text/Signature", Internet Draft <draft-vaudreuil-
signature-??.txt>
[BIN] Vaudreuil, G., "SMTP Service Extensions for Transmission of Large
and Binary MIME Messages", Internet Draft <draft-vaudreuil-
binary-??.txt>
[NOTIFY] Vaudreuil, G., Moore, K., "An Extensible Message Format for
Delivery Status Notifications", Internet Draft <draft-ietf-
notary-mime-delivery-0?-txt>
[NOTIFY2] Vaudreuil, G., "Multipart/Report", Internet-Draft, <draft-ietf-
notary-mime-report-0?.txt>
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[DSN] Moore, K. "SMTP Service Extensions for Delivery Status
Notifications", Internet Draft <draft-ietf-notary-smtp-drpt-
??.txt>.
9.Security Consideration
This document is a profile of existing Internet mail protcools. As such,
it does create any security issues not already existing in the profiled
Internet mail protocols themselves.
10. Author's Address
Gregory M. Vaudreuil
Octel Communications Corporation
Network Services Divison
17080 Dallas Parkway
Dallas, TX 75248-1905
214-733-2722
Greg.Vaudreuil@ONS.Octel.Com
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11. Appendix - Example Voice Message
The following message is a full-featured, all-options-enabled message
addressed to two recipients. The message includes the sender's spoken name
and a short speech segment. The message is marked as important and
private. Read receipts and positive delivery acknowledgment are requested.
To: 2145551212@vm1.mycompany.com
To: 2145551234@mv1.mycompany.com
From: 2175552345@VM2.mycompany.com
Date: Mon, 26 Aug 93 10:20:20 CST
MIME-Version: 1.0 (Voice Profile Version 1)
Content-type: Multipart/Mixed; Boundary = "MessageBoundary"
Content-Transfer-Encoding: 7bit
Message-ID: VM1.mycompany.co-123456789
Sensitivity: PrivateImportance: High
--MessageBoundary
Content-type: Text/Signature
Name: User, Joe, R. (Joe Random User)
SpokenName: lslfdslsertiflkTfpgkTportrpkTpfgTpoiTpssdasddasdasd
(This is the base-64 encoded spoken name)
o45itj09fiuvdkjgWlakgQ93ijkpokfpgokQ90geQ5tkjpokfgW
dlkgpokpeowrit09IpokporkgwI==
Capabilities: Audio/Basic, Audio/ADPCM, Application/Signature,
Image/G3Fax
--MessageBoundary
Content-type: Audio/ADPCM
Content-Transfer-Encoding: Base-64
glslfdslsertiflkTfpgkTportrpkTpfgTpoiTpdadasssdasddasdasd
(This is a sample of the base-64 message data) fgdhgdfgd
jrgoij3o45itj09fiuvdkjgWlakgQ93ijkpokfpgokQ90gQ5tkjpokfgW
dlkgpokpeowrit09==
--MessageBoundary--