A Message Summary and Message Waiting Indication Event Package for the Session Initiation Protocol (SIP)
RFC 3842

Network Working Group R. Mahy
Request for Comments: 3842 Cisco Systems, Inc.
Category: Standards Track August 2004
 A Message Summary and Message Waiting Indication Event Package for
 the Session Initiation Protocol (SIP)
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 describes a Session Initiation Protocol (SIP) event
 package to carry message waiting status and message summaries from a
 messaging system to an interested User Agent.
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Table of Contents
 1. Conventions . . . . . . . . . . . . . . . . . . . . . . . . 2
 2. Background and Appropriateness . . . . . . . . . . . . . . . 3
 3. Event Package Formal Definition . . . . . . . . . . . . . . 4
 3.1. Event Package Name . . . . . . . . . . . . . . . . . . 4
 3.2. Event Package Parameters . . . . . . . . . . . . . . . 4
 3.3. SUBSCRIBE Bodies . . . . . . . . . . . . . . . . . . . 4
 3.4. Subscription Duration. . . . . . . . . . . . . . . . . 4
 3.5. NOTIFY Bodies. . . . . . . . . . . . . . . . . . . . . 4
 3.6. Subscriber Generation of SUBSCRIBE Requests. . . . . . 6
 3.7. Notifier Processing of SUBSCRIBE Requests. . . . . . . 6
 3.8. Notifier Generation of NOTIFY Requests . . . . . . . . 7
 3.9. Subscriber Processing of NOTIFY Requests . . . . . . . 7
 3.10. Handling of Forked Requests. . . . . . . . . . . . . . 7
 3.11. Rate of Notifications. . . . . . . . . . . . . . . . . 7
 3.12. State Agents and Lists . . . . . . . . . . . . . . . . 8
 3.13. Behavior of a Proxy Server . . . . . . . . . . . . . . 8
 4. Examples of Usage . . . . . . . . . . . . . . . . . . . . . 8
 4.1. Example Message Flow . . . . . . . . . . . . . . . . . 8
 4.2. Example Usage with Callee Capabilities and Caller
 Preferences. . . . . . . . . . . . . . . . . . . . . . 14
 5. Formal Syntax . . . . . . . . . . . . . . . . . . . . . . . 14
 5.1. New Event-Package Definition . . . . . . . . . . . . . 15
 5.2. Body Format Syntax . . . . . . . . . . . . . . . . . . 15
 6. Security Considerations . . . . . . . . . . . . . . . . . . 15
 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . 16
 7.1. SIP Event Package Registration for message-summary . . 16
 7.2. MIME Registration for application/
 simple-message-summary . . . . . . . . . . . . . . . . 16
 8. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 17
 9. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . 17
 10. References . . . . . . . . . . . . . . . . . . . . . . . . . 17
 10.1. Normative References . . . . . . . . . . . . . . . . . 17
 10.2. Informational References . . . . . . . . . . . . . . . 18
 11. Author's Address . . . . . . . . . . . . . . . . . . . . . . 18
 12. Full Copyright Statement . . . . . . . . . . . . . . . . . . 19
1. Conventions
 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 BCP 14, RFC 2119 [3].
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2. Background and Appropriateness
 Message Waiting Indication is a common feature of telephone networks.
 It typically involves an audible or visible indication that messages
 are waiting, such as playing a special dial tone (which in telephone
 networks is called message-waiting dial tone), lighting a light or
 indicator on the phone, displaying icons or text, or some
 combination.
 Message-waiting dial tone is similar to but distinct from stutter
 dial tone. Both are defined in GR-506 [11].
 The methods in the SIP [1] base specification were only designed to
 solve the problem of session initiation for multimedia sessions, and
 rendezvous. Since Message Waiting Indication is really status
 information orthogonal to a session, it was not clear how an IP
 telephone acting as a SIP User Agent would implement comparable
 functionality. Members of the telephony community viewed this as a
 shortcoming of SIP.
 Users want the useful parts of the functionality they have using
 traditional analog, mobile, and PBX telephones. It is also desirable
 to provide comparable functionality in a flexible way that allows for
 more customization and new features. SIP Specific Event Notification
 (RFC 3265 -- SIP Events) [2] is an appropriate mechanism to use in
 this environment, as it preserves the user mobility and rendezvous
 features which SIP provides.
 Using SIP-Specific Event Notification, a Subscriber User Agent
 (typically an IP phone or SIP software User Agent) subscribes to the
 status of their messages. A SIP User Agent acting on behalf of the
 user's messaging system then notifies the Subscriber each time the
 messaging account's messages have changed. (This Notifier could be
 composed with a User Agent that provides a real-time media interface
 to send or receive messages, or it could be a stand-alone entity.)
 The Notifier sends a message summary in the body of a NOTIFY, encoded
 in a new MIME type defined later in this document. A User Agent can
 also explicitly fetch the current status.
 A SIP User Agent MAY subscribe to multiple accounts (distinguished by
 the Request URI). Multiple SIP User Agents MAY subscribe to the same
 account.
 Before any subscriptions or notifications are sent, each interested
 User Agent must be made aware of its messaging notifier(s). This MAY
 be manually configured on interested User Agents, manually configured
 on an appropriate SIP Proxy, or dynamically discovered based on
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 requested caller preferences [4] and registered callee capabilities
 [5]. (For more information on usage with callee capabilities, see
 Section 4.2)
3. Event Package Formal Definition
3.1. Event Package Name
 This document defines a SIP Event Package as defined in RFC 3265 [2].
 The event-package token name for this package is:
 "message-summary"
3.2. Event Package Parameters
 This package does not define any event package parameters.
3.3. SUBSCRIBE Bodies
 This package does not define any SUBSCRIBE bodies.
3.4. Subscription Duration
 Subscriptions to this event package MAY range from minutes to weeks.
 Subscriptions in hours or days are more typical and are RECOMMENDED.
 The default subscription duration for this event package is one hour.
3.5. NOTIFY Bodies
 A simple text-based format is proposed to prevent an undue burden on
 low-end user agents, for example, inexpensive IP phones with no
 display. Although this format is text-based, it is intended for
 machine consumption only.
 A future extension MAY define other NOTIFY bodies. If no "Accept"
 header is present in the SUBSCRIBE, the body type defined in this
 document MUST be assumed.
 The format specified in this proposal attempts to separate orthogonal
 attributes of messages as much as possible. Messages are separated
 by message-context-class (for example: voice-message, fax-message,
 pager-message, multimedia-message, text-message, and none), by
 message status (new and old), and urgent and non-urgent type.
 The text format begins with a simple status line, and optionally a
 summary line per message-context-class. Message-context-classes are
 defined in [7]. For each message-context-class, the total number of
 new and old messages is reported in the new and old fields.
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 In some cases, detailed message summaries are not available. The
 status line allows messaging systems or messaging gateways to provide
 the traditional boolean message waiting notification.
 Messages-Waiting: yes
 If the Request-URI or To header in a message-summary subscription
 corresponds to a group or collection of individual messaging
 accounts, the notifier MUST specify to which account the message-
 summary body corresponds. Note that the account URI MUST NOT be
 delimited with angle brackets ("<" and ">").
 Message-Account: sip:alice@example.com
 In the example that follows, more than boolean message summary
 information is available to the User Agent. There are two new and
 four old fax messages.
 Fax-Message: 2/4
 After the summary, the format can optionally list a summary count of
 urgent messages. In the next example there are one new and three old
 voice messages, none of the new messages are urgent, but one of the
 old messages is. All counters have a maximum value of 4,294,967,295
 ((2^32) - 1). Notifiers MUST NOT generate a request with a larger
 value. Subscribers MUST treat a larger value as 2^32-1.
 Voice-Message: 1/3 (0/1)
 Optionally, after the summary counts, the messaging systems MAY
 append RFC 2822 style message headers [9], which further describe
 newly added messages. Message headers MUST NOT be included in an
 initial NOTIFY, as new messages could be essentially unbounded in
 size. Message headers included in subsequent notifications MUST only
 correspond to messages added since the previous notification for that
 subscription. A messaging system which includes message headers in a
 NOTIFY MUST provide an administrator configurable mechanism to select
 which headers are sent. Headers likely for inclusion are To, From,
 Date, Subject, and Message-ID. Note that the formatting of these
 headers in this body is identical to that of SIP extension-headers,
 not the (similar) format defined in RFC 2822.
 Implementations which generate large notifications are reminded to
 follow the message size restrictions for unreliable transports
 articulated in Section 18.1.1 of SIP [1].
 Mapping local message state to new/old message status and urgency is
 an implementation issue of the messaging system. However, the
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 messaging notifier MUST NOT consider a message "old" merely because
 it generated a notification, as this could prevent another
 subscription from accurately receiving message-summary notifications.
 Likewise, the messaging system MAY use any suitable algorithm to
 determine that a message is "urgent".
 Messaging systems MAY use any algorithm for determining the
 appropriate message-context-class for a specific message. Systems
 which use Internet Mail SHOULD use the contents of the Message-
 Context header [7] (defined in RFC 3458) if present as a hint to make
 a context determination. Note that a composed messaging system does
 not need to support a given context in order to generate
 notifications identified with that context.
3.6. Subscriber Generation of SUBSCRIBE Requests
 Subscriber User Agents will typically SUBSCRIBE to message summary
 information for a period of hours or days, and automatically attempt
 to re-SUBSCRIBE well before the subscription is completely expired.
 If re-subscription fails, the Subscriber SHOULD periodically retry
 again until a subscription is successful, taking care to backoff to
 avoid network congestion. If a subscription has expired, new re-
 subscriptions MUST use a new Call-ID.
 The Subscriber SHOULD SUBSCRIBE to that user's message summaries
 whenever a new user becomes associated with the device (a new login).
 The Subscriber MAY also explicitly fetch the current status at any
 time. The subscriber SHOULD renew its subscription immediately after
 a reboot, or when the subscriber's network connectivity has just been
 re-established.
 The Subscriber MUST be prepared to receive and process a NOTIFY with
 new state immediately after sending a new SUBSCRIBE, a SUBSCRIBE
 renewal, an unsubscribe, a fetch, or at any other time during the
 subscription.
 When a user de-registers from a device (logoff, power down of a
 mobile device, etc.), subscribers SHOULD unsubscribe by sending a
 SUBSCRIBE message with an Expires header of zero.
3.7. Notifier Processing of SUBSCRIBE Requests
 When a SIP Messaging System receives SUBSCRIBE messages with the
 message-summary event-type, it SHOULD authenticate the subscription
 request. If authentication is successful, the Notifier MAY limit the
 duration of the subscription to an administrator defined amount of
 time as described in SIP Events [2].
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3.8. Notifier Generation of NOTIFY Requests
 Immediately after a subscription is accepted, the Notifier MUST send
 a NOTIFY with the current message summary information. This allows
 the Subscriber to resynchronize its state. This initial
 synchronization NOTIFY MUST NOT include the optional RFC 2822 style
 message headers [8].
 When the status of the messages changes sufficiently for a messaging
 account to change the number of new or old messages, the Notifier
 SHOULD send a NOTIFY message to all active subscribers of that
 account. NOTIFY messages sent to subscribers of a group or alias,
 MUST contain the message account name in the notification body.
 A Messaging System MAY send a NOTIFY with an "Expires" header of "0"
 and a "Subscription-State" header of "terminated" before a graceful
 shutdown.
3.9. Subscriber Processing of NOTIFY Requests
 Upon receipt of a valid NOTIFY request, the subscriber SHOULD
 immediately render the message status and summary information to the
 end user in an implementation specific way.
 The Subscriber MUST be prepared to receive NOTIFYs from different
 Contacts corresponding to the same SUBSCRIBE. (The SUBSCRIBE may
 have been forked).
3.10. Handling of Forked Requests
 Forked requests are allowed for this event type and may install
 multiple subscriptions. The Subscriber MAY render multiple summaries
 corresponding to the same account directly to the user, or MAY merge
 them as described below.
 If any of the "Messages-Waiting" status lines report "yes", then the
 merged state is "yes"; otherwise the merged state is "no".
 The Subscriber MAY merge summary lines in an implementation-specific
 way if all notifications contain at least one msg-summary line.
3.11. Rate of Notifications
 A Notifier MAY choose to hold NOTIFY requests in "quarantine" for a
 short administrator-defined period (seconds or minutes) when the
 message status is changing rapidly. Requests in the quarantine which
 become invalid are replaced by newer notifications, thus reducing the
 total volume of notifications. This behavior is encouraged for
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 implementations with heavy interactive use. Note that timely
 notification resulting in a change of overall state (messages waiting
 or not) and notification of newly added messages is probably more
 significant to the end user than a notification of newly deleted
 messages which do not affect the overall message waiting state (e.g.,
 there are still new messages).
 Notifiers SHOULD NOT generate NOTIFY requests more frequently than
 once per second.
3.12. State Agents and Lists
 A Subscriber MAY use an "alias" or "group" in the Request-URI of a
 subscription if that name is significant to the messaging system.
 Implementers MAY create a service which consolidates and summarizes
 NOTIFYs from many Contacts. This document does not preclude
 implementations from building state agents which support this event
 package. One way to implement such a service is with the event list
 extension [10].
3.13. Behavior of a Proxy Server
 There are no additional requirements on a SIP Proxy, other than to
 transparently forward the SUBSCRIBE and NOTIFY methods as required in
 SIP. However, Proxies SHOULD allow non-SIP URLs. Proxies and
 Redirect servers SHOULD be able to direct the SUBSCRIBE request to an
 appropriate messaging notifier User Agent.
4. Examples of Usage
4.1. Example Message Flow
 The examples shown below are for informational purposes only. For a
 normative description of the event package, please see sections 3 and
 5 of this document.
 In the example call flow below, Alice's IP phone subscribes to the
 status of Alice's messages. Via headers are omitted for clarity.
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 Subscriber Notifier
 | |
 | A1: SUBSCRIBE (new) |
 |---------------------->|
 | A2: 200 OK |
 |<----------------------|
 | |
 | A3: NOTIFY (sync) |
 |<----------------------|
 | A4: 200 OK |
 |---------------------->|
 | |
 | |
 | A5: NOTIFY (change) |
 |<----------------------|
 | A6: 200 OK |
 |---------------------->|
 | |
 | |
 | A7: (re)SUBSCRIBE |
 |---------------------->|
 | A8: 200 OK |
 |<----------------------|
 | |
 | A9: NOTIFY (sync) |
 |<----------------------|
 | A10: 200 OK |
 |---------------------->|
 | |
 | |
 | A11: (un)SUBSCRIBE |
 |---------------------->|
 | A12: 200 OK |
 |<----------------------|
 | |
 | A13: NOTIFY (sync) |
 |<----------------------|
 | A14: 200 OK |
 |---------------------->|
 A1: Subscriber (Alice's phone) ->
 Notifier (Alice's voicemail gateway)
 Subscribe to Alice's message summary status for 1 day.
 SUBSCRIBE sip:alice@vmail.example.com SIP/2.0
 To: <sip:alice@example.com>
 From: <sip:alice@example.com>;tag=78923
 Date: 2000年7月10日 03:55:06 GMT
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 Call-Id: 1349882@alice-phone.example.com
 CSeq: 4 SUBSCRIBE
 Contact: <sip:alice@alice-phone.example.com>
 Event: message-summary
 Expires: 86400
 Accept: application/simple-message-summary
 Content-Length: 0
 A2: Notifier -> Subscriber
 SIP/2.0 200 OK
 To: <sip:alice@example.com>;tag=4442
 From: <sip:alice@example.com>;tag=78923
 Date: 2000年7月10日 03:55:07 GMT
 Call-Id: 1349882@alice-phone.example.com
 CSeq: 4 SUBSCRIBE
 Expires: 86400
 Content-Length: 0
 A3: Notifier -> Subscriber
 (immediate synchronization of current state:
 2 new and 8 old [2 urgent] messages)
 NOTIFY sip:alice@alice-phone.example.com SIP/2.0
 To: <sip:alice@example.com>;tag=78923
 From: <sip:alice@example.com>;tag=4442
 Date: 2000年7月10日 03:55:07 GMT
 Call-Id: 1349882@alice-phone.example.com
 CSeq: 20 NOTIFY
 Contact: <sip:alice@vmail.example.com>
 Event: message-summary
 Subscription-State: active
 Content-Type: application/simple-message-summary
 Content-Length: 99
 Messages-Waiting: yes
 Message-Account: sip:alice@vmail.example.com
 Voice-Message: 2/8 (0/2)
 A4: Subscriber -> Notifier
 SIP/2.0 200 OK
 To: <sip:alice@example.com>;tag=78923
 From: <sip:alice@example.com>;tag=4442
 Date: 2000年7月10日 03:55:08 GMT
 Call-Id: 1349882@alice-phone.example.com
 CSeq: 20 NOTIFY
 Content-Length: 0
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 A5: Notifier -> Subscriber
 This is a notification of new messages.
 Some headers from each of the new messages are appended.
 NOTIFY sip:alice@alice-phone.example.com SIP/2.0
 To: <sip:alice@example.com>;tag=78923
 From: <sip:alice@example.com>;tag=4442
 Date: 2000年7月10日 04:28:53 GMT
 Contact: <sip:alice@vmail.example.com>
 Call-ID: 1349882@alice-phone.example.com
 CSeq: 31 NOTIFY
 Event: message-summary
 Subscription-State: active
 Content-Type: application/simple-message-summary
 Content-Length: 503
 Messages-Waiting: yes
 Message-Account: sip:alice@vmail.example.com
 Voice-Message: 4/8 (1/2)
 To: <alice@atlanta.example.com>
 From: <bob@biloxi.example.com>
 Subject: carpool tomorrow?
 Date: 2000年7月09日 21:23:01 -0700
 Priority: normal
 Message-ID: 13784434989@vmail.example.com
 To: <alice@example.com>
 From: <cathy-the-bob@example.com>
 Subject: HELP! at home ill, present for me please
 Date: 2000年7月09日 21:25:12 -0700
 Priority: urgent
 Message-ID: 13684434990@vmail.example.com
 A6: Subscriber -> Notifier
 SIP/2.0 200 OK
 To: <sip:alice@example.com>;tag=78923
 From: <sip:alice@example.com>;tag=4442
 Date: 2000年7月10日 04:28:53 GMT
 Call-ID: 1349882@alice-phone.example.com
 CSeq: 31 NOTIFY
 Content-Length: 0
 A7: Subscriber -> Notifier
 Refresh subscription.
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 SUBSCRIBE sip:alice@vmail.example.com SIP/2.0
 To: <sip:alice@example.com>;tag=4442
 From: <sip:alice@example.com>;tag=78923
 Date: 2000年7月10日 15:55:06 GMT
 Call-Id: 1349882@alice-phone.example.com
 CSeq: 8 SUBSCRIBE
 Contact: <sip:alice@alice-phone.example.com>
 Event: message-summary
 Expires: 86400
 Accept: application/simple-message-summary
 Content-Length: 0
 A8: Notifier -> Subscriber
 SIP/2.0 200 OK
 To: <sip:alice@example.com>;tag=4442
 From: <sip:alice@example.com>;tag=78923
 Date: 2000年7月10日 15:55:07 GMT
 Call-Id: 1349882@alice-phone.example.com
 CSeq: 8 SUBSCRIBE
 Contact: <sip:alice@alice-phone.example.com>
 Expires: 86400
 Content-Length: 0
 A9: Notifier -> Subscriber
 (immediate synchronization of current state)
 NOTIFY sip:alice@alice-phone.example.com SIP/2.0
 To: <sip:alice@example.com>;tag=78923
 From: <sip:alice@example.com>;tag=4442
 Date: 2000年7月10日 15:55:07 GMT
 Call-Id: 1349882@alice-phone.example.com
 CSeq: 47 NOTIFY
 Contact: <sip:alice@vmail.example.com>
 Event: message-summary
 Subscription-State: active
 Content-Type: application/simple-message-summary
 Content-Length: 99
 Messages-Waiting: yes
 Message-Account: sip:alice@vmail.example.com
 Voice-Message: 4/8 (1/2)
 A10: Subscriber -> Notifier
 SIP/2.0 200 OK
 To: <sip:alice@example.com>;tag=78923
 From: <sip:alice@example.com>;tag=4442
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 Date: 2000年7月10日 15:55:08 GMT
 Call-Id: 1349882@alice-phone.example.com
 CSeq: 47 NOTIFY
 Contact: <sip:alice@vmail.example.com>
 A11: Subscriber -> Notifier
 Un-subscribe after "alice" logs out.
 SUBSCRIBE sip:alice@vmail.example.com SIP/2.0
 To: <sip:alice@example.com>;tag=4442
 From: <sip:alice@example.com>;tag=78923
 Date: 2000年7月10日 19:35:06 GMT
 Call-Id: 1349882@alice-phone.example.com
 CSeq: 17 SUBSCRIBE
 Contact: <sip:alice@alice-phone.example.com>
 Event: message-summary
 Expires: 0
 Accept: application/simple-message-summary
 Content-Length: 0
 A12: Notifier -> Subscriber
 SIP/2.0 200 OK
 To: <sip:alice@example.com>;tag=4442
 From: <sip:alice@example.com>;tag=78923
 Date: 2000年7月10日 19:35:07 GMT
 Call-Id: 1349882@alice-phone.example.com
 CSeq: 17 SUBSCRIBE
 Contact: <sip:alice@alice-phone.example.com>
 Expires: 0
 Content-Length: 0
 A13: Notifier -> Subscriber
 (immediate synchronization of current state,
 which the subscriber can now ignore)
 NOTIFY sip:alice@alice-phone.example.com SIP/2.0
 To: <sip:alice@example.com>;tag=78923
 From: <sip:alice@example.com>;tag=4442
 Date: 2000年7月10日 19:35:07 GMT
 Call-Id: 1349882@alice-phone.example.com
 CSeq: 56 NOTIFY
 Contact: <sip:alice@vmail.example.com>
 Event: message-summary
 Subscription-State: terminated;reason=timeout
 Content-Type: application/simple-message-summary
 Content-Length: 99
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 Messages-Waiting: yes
 Message-Account: sip:alice@vmail.example.com
 Voice-Message: 4/8 (1/2)
 A14: Subscriber -> Notifier
 SIP/2.0 200 OK
 To: <sip:alice@example.com>;tag=78923
 From: <sip:alice@example.com>;tag=4442
 Date: 2000年7月10日 19:35:08 GMT
 Call-Id: 1349882@alice-phone.example.com
 CSeq: 56 NOTIFY
 Event: message-summary
 Content-Length: 0
4.2. Example Usage with Callee Capabilities and Caller Preferences
 The use of callee capabilities is optional but encouraged. If callee
 capabilities are used, a messaging notifier MAY REGISTER a Contact
 with an appropriate methods and events tag as shown in the example
 below. To further distinguish itself, the messaging notifier MAY
 also REGISTER as a Contact with the actor="msg-taker" tag. An
 example of this kind of registration follows below.
 REGISTER sip:sip3-sj.example.com SIP/2.0
 To: <sip:alice@example.com>
 From: <sip:alice@example.com>;tag=4442
 ...
 Contact: <sip:alice@vm13-sj.example.com>
 ;actor="msg-taker";methods="SUBSCRIBE"
 ;automata;events="message-summary"
 The following SUBSCRIBE message would find the Contact which
 registered in the example above.
 SUBSCRIBE sip:alice@example.com SIP/2.0
 ...
 Accept: application/simple-message-summary
 Event: message-summary
 Accept-Contact: *;automata;actor="msg-taker"
5. Formal Syntax
 The following syntax specification uses the augmented Backus-Naur
 Form (BNF) as described in RFC 2234 [6].
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5.1. New Event-Package Definition
 This document defines a new event-package with the package name:
 message-summary
5.2. Body Format Syntax
 The formal syntax for the application/simple-message-summary MIME
 type is described below. The message-context-class production is
 defined in Section 6.2 of RFC 3458 [7]. Note that all productions
 described here are case insensitive.
 message-summary = msg-status-line CRLF
 [msg-account CRLF]
 [*(msg-summary-line CRLF)]
 [ *opt-msg-headers ]
 msg-status-line = "Messages-Waiting" HCOLON msg-status
 msg-status = "yes" / "no"
 msg-account = "Message-Account" HCOLON Account-URI
 Account-URI = SIP-URI / SIPS-URI / absoluteURI
 msg-summary-line = message-context-class HCOLON newmsgs SLASH oldmsgs
 [ LPAREN new-urgentmsgs SLASH old-urgentmsgs RPAREN ]
 opt-msg-headers = CRLF 1*(extension-header CRLF)
 newmsgs = msgcount
 oldmsgs = msgcount
 new-urgentmsgs = msgcount
 old-urgentmsgs = msgcount
 msgcount = 1*DIGIT ; MUST NOT exceed 2^32-1
6. Security Considerations
 Message summaries and optional message bodies contain information
 which is typically very privacy sensitive. At a minimum,
 subscriptions to this event package SHOULD be authenticated and
 properly authorized. Furthermore, notifications SHOULD be encrypted
 and integrity protected using either end-to-end mechanisms, or the
 hop-by-hop protection afforded messages sent to SIPS URIs.
 Additional and privacy security considerations are discussed in
 detail in SIP [1] and SIP Events [2].
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7. IANA Considerations
7.1. SIP Event Package Registration for message-summary
 Package name: message-summary
 Type: package
 Contact: [Mahy]
 Published Specification: This document.
7.2. MIME Registration for application/simple-message-summary
 MIME media type name: application
 MIME subtype name: simple-message-summary
 Required parameters: none.
 Optional parameters: none.
 Encoding considerations: This MIME type was designed for
 use with protocols which can carry binary-encoded data.
 Although the format of this MIME type is similar to RFC 2822,
 it is not identical. (Specifically, line folding rules are
 SIP-specific and included URIs can contain non-ASCII
 characters.) Protocols which do not carry binary data
 (which have line length or character-set restrictions
 for example) MUST use a reversible transfer encoding
 (such as base64) to carry this MIME type.
 Security considerations: See the "Security Considerations"
 section in this document.
 Interoperability considerations: none
 Published specification: This document.
 Applications which use this media: The simple-message-summary
 application subtype supports the exchange of message waiting and
 message summary information in SIP networks.
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RFC 3842 SIP Message Waiting August 2004
 Additional information:
 1. Magic number(s): N/A
 2. File extension(s): N/A
 3. Macintosh file type code: N/A
8. Contributors
 Ilya Slain came up with the initial format of the text body contained
 in this document. He was previously listed as a co-author, however,
 he is no longer reachable.
9. Acknowledgments
 Thanks to Dan Wing, Dave Oran, Bill Foster, Steve Levy, Denise
 Caballero-McCann, Jeff Michel, Priti Patil, Satyender Khatter, Bich
 Nguyen, Manoj Bhatia, David Williams, and Bryan Byerly of Cisco,
 Jonathan Rosenberg and Adam Roach of Dynamicsoft, Eric Burger of
 Snowshore, Nir Chen of Comverse, and Eric Tremblay of Mediatrix.
10. References
10.1. Normative References
 [1] Rosenberg, J., Schulzrinne, H., Camarillo, G., Johnston, A.,
 Peterson, J., Sparks, R., Handley, M., and E. Schooler, "SIP:
 Session Initiation Protocol", RFC 3261, June 2002.
 [2] Roach, A.B., "Session Initiation Protocol (SIP)-Specific Event
 Notification", RFC 3265, June 2002.
 [3] Bradner, S., "Key words for use in RFCs to Indicate Requirement
 Levels", BCP 14, RFC 2119, March 1997.
 [4] Rosenberg, J., Schulzrinne, H., and P. Kyzivat, "Caller
 Preferences for the Session Initiation Protocol (SIP)", RFC
 3841, August 2004.
 [5] Rosenberg, J., Schulzrinne, H., and P. Kyzivat, "Indicating User
 Agent Capabilities in the Session Initiation Protocol (SIP)",
 RFC 3840, August 2004.
 [6] Crocker, D., Ed. and P. Overell, "Augmented BNF for Syntax
 Specifications: ABNF", RFC 2234, November 1997.
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RFC 3842 SIP Message Waiting August 2004
 [7] Burger, E., Candell, E., Eliot, C., and G. Klyne, "Message
 Context for Internet Mail", RFC 3458, January 2003.
10.2. Informational References
 [8] Freed, N. and N. Borenstein, "Multipurpose Internet Mail
 Extensions (MIME) Part Two: Media Types", RFC 2046, November
 1996.
 [9] Resnick, P., Ed., "Internet Message Format", RFC 2822, April
 2001.
 [10] Rosenberg, J., Roach, A.B., and B. Campbell, "A Session
 Initiation Protocol (SIP) Event Notification Extension for
 Resource Lists", Work in Progress, June 2003.
 [11] Telcordia, "GR-506: Signaling for Analog Interfaces, Issue 1,
 Revision 1", Nov 1996.
11. Author's Address
 Rohan Mahy
 Cisco Systems, Inc.
 5617 Scotts Valley Drive, Suite 200
 Scotts Valley, CA 95066
 USA
 EMail: rohan@cisco.com
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RFC 3842 SIP Message Waiting August 2004
12. Full Copyright Statement
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 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.
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Acknowledgement
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 Internet Society.
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