Lemonade Working Group J.K. Wong (Ed.) Internet Draft Nortel Networks Document: draft-ietf-lemonade-goals-01.txt Category: Informational Expires: April 2004 Oct 24, 2003 Goals for Internet Messaging to Support Diverse Service Environments Status of this Memo This document is an Internet-Draft and is in full conformance with all provisions of Section 10 of RFC2026. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF), its areas, and its working groups. Note that other groups may also distribute working documents as Internet-Drafts. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." The list of current Internet-Drafts can be accessed at http://www.ietf.org/ietf/1id-abstracts.txt The list of Internet-Draft Shadow Directories can be accessed at http://www.ietf.org/shadow.html Abstract The LEMONADE Working Group -- Internet Messaging to support diverse service environments -- is chartered to provide a set of enhancements and profiles to Internet email facilitating its use on hosts with constrained resources, and with high latency/limited bandwidth communications links. The enhanced Internet mail must continue to seamlessly support the existing service in conventional environments. The primary motivation for this effort is, by making Internet mail protocols richer -- more adaptable to varied media and environments - to allow their use over the mobile Internet. Driven by the requirements of wireless handheld devices, a discussion is given of the considerations in Internet messaging protocols to enable the support of multimedia messaging on limited capability messaging clients in diverse service environments. Also included is a list of general principles to guide the design of the enhanced messaging protocols. Finally, some issues around providing seamless service between enhanced Internet email and the existing separate mobile messaging infrastructure are briefly listed. This document attempts to capture the background, motivation and thinking behind the Lemonade design process. Discussion of this and related drafts are on the LEMONADE WG email list. To subscribe, send the message "subscribe" to lemonade-request@ietf.org. The public archive is in the directory at: ftp://ftp.ietf.org/ietf-mailing-lists/lemonade/ Wong Informational - Expires April 2004 1 LEMONADE Goals October 2003 1. Introduction ..............................................................4 2. Messaging Terminology and Models (Client to Server aspect only) ...........6 2.1. Messaging Transaction Models ..........................................6 2.2. Mobile Messaging Transactions .........................................6 2.2.1. Submission .........................................................7 2.2.2. Notification .......................................................7 2.2.3. Retrieval ..........................................................7 3. Profiles ..................................................................8 3.1. Existing Profiles .....................................................8 3.1.1. Voice Messaging (VPIMv2) ...........................................8 3.1.2. Fax ................................................................8 3.2. Useful Client Profiles ................................................8 3.2.1. TUI ................................................................8 3.2.2. Multi-modal clients ...............................................10 3.2.3. WUI ...............................................................10 4. General Principles .......................................................12 4.1. Protocol Conservation ................................................12 4.1.1. Reuse Existing Protocols ..........................................12 4.1.2. Maintain Existing Protocol Integrity ..............................12 4.2. Sensible Reception/Sending Context ...................................12 4.2.1. Reception Context .................................................12 4.2.2. Sending Context ...................................................12 4.3. Internet Infrastructure Preservation .................................12 4.4. Voice Requirements (Near real-time delivery) .........................13 4.5. Fax Requirements (guaranteed delivery) ...............................13 4.6. Video Requirements (scalable message size) ...........................13 5. Security Considerations ..................................................14 6. Issues and Requirements: TUI subset of WUI ...............................15 6.1. Requirements on the Message Retrieval protocol .......................15 6.1.1. Performance Issues ................................................15 6.1.2. Functional Issues .................................................16 6.2. Requirements on the Message Submission Protocol ......................17 6.2.1. Forward without Download Support ..................................17 6.2.2. Quota by Context Enforcement ......................................18 6.2.3. Future Delivery Support with Cancel ...............................18 6.2.4. Support for Committed Message Delivery ............................19 6.3. Requirements on Message Notification .................................19 6.3.1. Additional Requirements on Message Notification ...................19 7. Issues and Requirements: WUI Mobility Aspects ............................21 7.1. Wireless Considerations on Email .....................................21 7.1.1. Transport Considerations ..........................................21 7.1.2. Handset-Resident Client Limitations ...............................21 7.1.3. Wireless Bandwidth and Network Utilization Considerations .........21 7.1.4. Content Display Considerations ....................................22 7.2. Requirements to Enable Wireless Device Support .......................23 7.2.1. Transport Requirements ............................................23 7.2.2. Enhanced Mobile Email Functionality ...............................23 7.2.3. Client Requirements ...............................................24 7.2.4. Bandwidth Requirements ............................................24 7.2.5. Media Handling Requirements .......................................24 Wong Informational - Expires April 2004 2 LEMONADE Goals October 2003 8. Interoperation with Existing Mobile Messaging ............................26 8.1. Addressing of mobile devices .........................................26 8.2. Push model of Message Retrieval ......................................26 8.3. Operator Issues ......................................................26 8.3.1. Support for end-to-end delivery reports and read reports ..........26 8.3.2. Support for Selective Downloading .................................26 8.3.3. Transactions and Operator Charging Units ..........................26 8.3.4. Network Authentication ............................................26 9. Informative References ...................................................27 10. Acknowledgments .........................................................31 11. Editor's Address ........................................................32 12. Contributors's Addresses ................................................33 Conventions used in this document This document refers generically to the sender of a message in the masculine (he/him/his) and the recipient of the message in the feminine (she/her/hers). This convention is purely for convenience and makes no assumption about the gender of a message sender or recipient. FORMATTING NOTE: Notes, such at this one, provide additional nonessential information that the reader may skip without missing anything essential. The primary purpose of these non-essential notes is to convey information about the rationale of this document, or to place this document in the proper historical or evolutionary context. Readers whose sole purpose is to construct a conformant implementation may skip such information. However, it may be of use to those who wish to understand why we made certain design choices. 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 [RFC2119]. Wong Informational - Expires April 2004 3 LEMONADE Goals October 2003 1. Introduction Historically, a number of separate electronic messaging systems originated and evolved independently for different messaging modes. E.g. o Internet email systems evolved to support LAN networked computers with messages consisting of rich text plus attachments. o Voice mail systems utilized a client with a telephone-based or an answering machine style of user interface. The telephone network was used for transport of voice messages. o Fax store-and-forward users interface with a fax machine using a modified telephone based interface. Fax machines use the telephone network for transport of modem data. o With cellular phones, SMS (Short Message Service) enabled users to send short text messages between their devices. In the recent past, IETF email standards have evolved to support additional/merged functionality: o With MIME, the Internet email transport was enhanced to carry any kind of digital data o Email protocols were extended and profiled by VPIM and iFAX so that properly enabled voice mail systems and fax machines could use the common email infrastructure to carry their messages over the Internet as an alternative to the telephone network. These enhancements were such that the user's experience of reliability, security and responsiveness were not diminished by transport over the Internet These successes -- making Internet email transport the common infrastructure supporting what were separate messaging universes -- have encouraged a new vision: to provide, over the Internet, a single infrastructure, mailbox, and set of protocols for a user to get, respond to, and manipulate all of his or her messages from a collection of clients with varying capabilities, operating in diverse environments. The Lemonade effort -- Internet Messaging to support diverse service environments -- realizes this vision further by enabling Internet mail support for mobile devices and facilitating its interoperability with the existing mobile messaging universe. In the recent past, messaging standards for resource limited mobile devices have evolved to keep pace with rapid innovation: o In the cellular space, SMS was enhanced to EMS (Extended Message Service) allowing longer text messages, images and graphics. With an even richer feature set, Multimedia Messaging (MMS) was developed as a lightweight access mechanism for the transmission of pictures, audio, and motion pictures. MMS protocols are based in part on various messaging and web Internet standards as well as SMS. The cellular messaging universe is a separate special infrastructure adapted to deliver appropriate functionality in a timely and effective manner to a special environment. Wong Informational - Expires April 2004 4 LEMONADE Goals October 2003 o As well , the number of different mobile clients that need to be supported keeps proliferating. (e.g. besides cellular phones there are wireless enabled PDAs, tablet computers, etc.) These resource limited mobile devices are generally less powerful both in processing speed and display capabilities than conventional computers. They are also connected to the network by wireless links whose bandwidth is lower, latency is longer, and costs are higher than traditional wire-line links hence the stress on the need to support adaptation to a whole different service environment. The purpose of this document is to discuss issues impeding the IETF email protocols from support of the mobile service environment. As a result of the discussion considerations are documented and in some cases possible approaches to solutions are suggested. It turns out that the enhancements to support mobile clients also offer benefits for some terminals in conventional environments. In particular the enhancements address the needs of the following diverse clients: o A wireless handheld device with an email client -- a Wireless User Interface (WUI) mode of user interaction is dictated by the constraints of the wireless handheld operating environment o A Telephone-based audio client -- a Telephone User Interface(TUI), this is the user mode offered by a POTS set o This is a subset of the WUI and is useful in other contexts o A Multi-modal messaging client providing a coordinated messaging session using display and audio modes simultaneously. (e.g. a system consisting of a PC with a phone or a wireless phone with both a voice circuit and data channel requiring coordination). o This is also a subset of the WUI and is useful in other contexts The rest of this document is structured as follows: o A brief survey of messaging profiles - - both existing and yet to be defined o A list of principles to be used to guide the design of Internet Messaging for diverse service environments o Detailed discussion on enhancements to Internet mail protocols to support WUIs. o Some issues relating to the interoperation of enhanced Internet mail and the existing mobile messaging services Wong Informational - Expires April 2004 5 LEMONADE Goals October 2003 2. Messaging Terminology and Models (Client to Server aspect only) A client server model is prevalent in existing messaging architectures. The client, also known as a "user agent", presents messages to and accepts messages from the user. The server, also known as a "relay/server" or a "proxy-relay", provides storage and delivery of messages 2.1. Messaging Transaction Models There are two basic transactional models. In the "pull" model, the component rather than the data flow initiates the transaction. E.g., a client may initiate a connection to a server and issue requests to the server to deliver incoming messages. Conventional email clients, web-mail clients, and WAP-based mobile clients use the "pull" model. The "push" model differs in that the component initiating the transaction does so because of some data flow affecting it. E.g., the arrival of a new message at the terminating server may cause a notification to be sent ("pushed") to a messaging client. 2.2. Mobile Messaging Transactions The most common functions are: "submission", "notification", and "retrieval". There may be other functions, such as "delivery reports", "read-reply reports", "forwarding", "view mailbox", "store message", etc. Each of these transactions can be implemented in either a pull or push model. However, some transactions are more naturally suited to one model or another. The following figure is a depiction of a simple client-server model (no server to server interactions shown): (1) Message submission (2) Message notification (3) & (4) Message retrieval +-------+ +------+ +-------+ |Mail |-------(1)------>| |-----------(2)-------->|Mail | |Client | Submit msg | | Notification /|Client | +-------+ | | / +--+----+ | | / ^ | |<----------(3)-----+ / |Server| Retrieval request / | | / | | / | |-----------(4)-------+ | | Retrieval response | | +------+ - Simple Messaging Model Wong Informational - Expires April 2004 6 LEMONADE Goals October 2003 2.2.1. Submission "Submission" is the transaction between a client and a server by which the user of the former sends a new message to another user. Submission is a push from client to server. 2.2.2. Notification "Notification" is the transaction by with the server notifies the client that it has received messages intended for that client. Notification is a push from server to client. All of the larger mobile messaging systems implement a push model for the notification because data is presented to the user without the user having to experience network/transport latencies, and without tying up network resources for polling when there is no new data. Conventional email differs in that it has not seen the need so far for a standardized notification protocol. 2.2.3. Retrieval "Retrieval" is the transaction between a client and a server by which the client can obtain one or more messages from the server. Retrieval can be push or pull. Implemented in some mobile systems as an option, the push model has the advantage of the user not necessarily being aware of transport or network latencies The pull model, implemented in most systems, mobile or conventional, has the advantage that the user can control what data is actually sent to and stored by the client. Wong Informational - Expires April 2004 7 LEMONADE Goals October 2003 3. Profiles Internet messaging can be support a variety of client and server types other than traditional email. The clients may be adapted for host restrictions such as limited processing power, message store, display window size, etc. Alternatively clients may be adapted for different functionality (e.g. voice mail, fax, etc.). Servers may support optional mail features that would allow better handling of different media (e.g. voice mail, fax, video, etc.). Grouping together features needed to support a particular application is to define an Internet Mail profile for that application. 3.1. Existing Profiles The following profiles are examples of server-to-server profiles of SMTP and MIME. They do not address client-to-server interactions. 3.1.1. Voice Messaging (VPIMv2) These profiles [RFC2421 to RFC2424] enable the transport of voice messages using the Internet mail system. The main driver for this work was support of IP transport for voice mail systems. As voice mail clients are accustomed to a higher degree of responsiveness and certainty as to message delivery, the functionality added by VPIMv2 includes Message Disposition Notification and Delivery Status Message as well as the addition of voice media to multi-part message bodies. 3.1.2. Fax This set of profiles [RFC2301 to RFC2306] enables the transport of fax using Internet mail protocols. This work defined the image/tiff MIME type. Support for fax clients also required extensions to Message Delivery Notification. 3.2. Useful Client Profiles 3.2.1. TUI It is desirable to replace proprietary protocols between telephone user interface clients and message stores with standards-based interfaces. The proprietary protocols were created to provide media-aware capabilities as well as provide the low-latency required by some messaging applications. An example of a TUI client is a voice mail client. Since a POTS phone is a totally dumb terminal, the voice mail client functionality has to be provided by a user agent networked to the mail server. The main architectural difference between a conventional voice mail system and an Internet messaging system supporting a TUI is that the voice mail system uses a specialized message store and protocols. Wong Informational - Expires April 2004 8 LEMONADE Goals October 2003 Architecture of current voice mail systems implementing VPIMv2: |---------------| |-------| RFC-822/MIME | | | | |---------------------------| MTA | | | | mail submission -> | | (E)SMTP Telephone--|TUI|TUA| |------| |--to another | | | Proprietary Protocol | | | email | | |---------------------------| MS | | server |-------| <- mail retrieval | | | |---------------| mail client email server |----------------voice messaging system ---------------| Mail client consists of: TUI (Telephone User Interface) and TUA (Telephone User Agent) Communication between TUI and TUA is proprietary Email server consists of: MS (Mail Store) and MTA (Message Transfer Agent) Communication between MS and MTA is proprietary It is proposed that the Proprietary Protocol be replaced with an IETF standard protocol: |---------------| |-------| RFC-822/MIME | | | | |---------------------------| MTA | | | | mail submission -> | | (E)SMTP Telephone--|TUI|TUA| |------| |--to another | | | IETF protocol | | | mail | | |---------------------------| MS | | server |-------| <- mail retrieval | | | |---------------| mail client email server |- voice mail system-| |--mail server--| Mail client consists of: TUI (Telephone User Interface) and TUA (Telephone User Agent) Communication between TUI and TUA is proprietary Email server consists of: MS (Mail Store) and MTA (Message Transfer Agent) Communication between MS and MTA is proprietary Wong Informational - Expires April 2004 9 LEMONADE Goals October 2003 3.2.2. Multi-modal clients Multi-modal clients offer the potential of coordinated voice and data modes of user interaction. Architecturally, the multi-modal client can be considered the union two user agent components - - - -- one a TUI client, the other a simple GUI client. See next figure. The GUA helps maintain the text display while the TUA acts on behalf of the TUI functionality. This model is the norm with cellular devices supporting data access since these evolved historically from cell phones to which a data channel was added. Architecturally, there are also situations where this model is appropriate. (Maybe the client host processor power and radio channel bandwidth are insufficient to handle the voice processing needed for text recognition or text to speech. Presenting two completely different modes of user interaction may be desirable in itself.) 3.2.3. WUI The Wireless user interface is functionally equivalent to a conventional email client on a personal workstation, but is optimized for the limited memory, processing, latency, bandwidth, and relatively high bandwidth cost. As already alluded to above, in many cases (e.g. cellular devices), the mobile client is multi-modal one. So WUIs can be modeled as resource-and- link-limited multi-modal clients. These terminals require the use of protocols that minimize the number of over-the-air transactions and reduce the amount of data that needs be transmitted over the air overall. Such reduction in over-the-air transmission is a combination of more efficient protocol interaction and richer message presentation choices allowing a user to more intelligently select what should be downloaded and what should remain on the server. While not an explicit goal, it is desirable to provide equivalent functionality to the wireless MMS service as defined by 3GPP, 3GPP2, and the OMA. Wong Informational - Expires April 2004 10 LEMONADE Goals October 2003 Wireless User Interface(WUI)/Multi-modal Clients Proposed: |wireless GUI client| email server (E)SMTP (client-server) |---------------| |-------| RFC-822/MIME | | | | |---------------------------| | | | | mail submission -> | | (E)SMTP -|GUI|GUA| | |--to another | | | | IETF standard protocol |------------ | mail | | | |----------------------------to MS below| | server | |-------| <- mail retrieval |------------ | | | | | Handheld | | | | Device WUI | | MTA | | | | | | | | | | |-------| RFC-822/MIME | | | | | |---------------------------| | | | | | mail submission -> | | -|TUI|TUA| |------| | | | | IETF standard protocol | | | | | |---------------------------| MS | | |-------| <- mail retrieval | | | |---------------| TUI client voice mail server |----------------voice messaging system ----------------| |----- WUI-----| |---mail server----| Wireless GUI client consists of: GUI (Graphical User Interface) And GUA (Graphical User Agent) Communication between UI and UA is proprietary TUI client consists of: TUI (Telephone User Interface) and TUA (Telephone User Agent) Communication between TUI and TUA is proprietary Communication between GUA and TUA is proprietary Mail (email and voice mail) server consists of: MS (Mail Store) and MTA (Message Transfer Agent) Communication between MS and MTA is proprietary Wong Informational - Expires April 2004 11 LEMONADE Goals October 2003 4. General Principles This is a list of principles to guide the design of extensions for Internet Messaging systems and protocols to support diverse endpoints. 4.1. Protocol Conservation 4.1.1. Reuse Existing Protocols To the extent feasible, the enhanced messaging framework SHOULD use existing protocols whenever possible. 4.1.2. Maintain Existing Protocol Integrity In meeting requirement 4.1, the enhanced messaging framework MUST NOT redefine the semantics of an existing protocol. Extensions, based on capability declaration by the server, will be used to introduce new functionality where required. Said differently, we will not break existing protocols. 4.2. Sensible Reception/Sending Context 4.2.1. Reception Context When the user receives a message, that message SHOULD receive the treatment expected by the sender. For example, if the sender believes he is sending a voice message, voice message semantics should prevail to the extent that the receiving client can support such treatment. 4.2.2. Sending Context When the user sends a message, he SHOULD be able to specify the message context. That is, whether the network should treat the message as an Internet Mail message, voice message, video message, etc. Again, this can only be complied with to the extent that the infrastructure and receiving client can provide such treatment. In practice, this would imply that the message should be in the form desired by the sender up to delivery to the receiving client. 4.3. Internet Infrastructure Preservation The infrastructure SHOULD change only where required for new functionality. Existing functionality MUST be preserved on the existing infrastructure, that is, all extensions must be backward compatible. There MUST be no flag days. Messages created in an enhanced messaging context MUST NOT require changes to existing mail clients. However, there may be a loss in service in certain circumstances. Wong Informational - Expires April 2004 12 LEMONADE Goals October 2003 The enhanced messaging framework MUST be able to handle messages created in a non-enhanced messaging context, for example, a simple, [RFC 822] text message. 4.4. Voice Requirements (Near real-time delivery) On the retrieval side, there are significant real-time requirements for retrieving a message for voice playback. More than any other media type, including video, voice is extremely sensitive to variations in playback latency. The enhanced messaging framework MUST address the real-time needs of voice. 4.5. Fax Requirements (guaranteed delivery) Fax users have a particular expectation that is a challenge for enhanced Internet messaging. When a person sends a fax, their expectation is the user has received the message upon successful transmission. This clearly is not the case for Internet Mail. This issue is not addressed in Lemonade. 4.6. Video Requirements (scalable message size) Video mail has one outstanding feature: Video messages are potentially large! The enhanced messaging framework MUST scale for very large messages. Streaming from the server to the client and vice-versa must be supported. Wong Informational - Expires April 2004 13 LEMONADE Goals October 2003 5. Security Considerations Security will be a very important part of enhanced messaging. The goal, wherever possible, is to preserve the semantics of existing messaging systems and meet the (existing) expectations of users with respect to security and reliability. Wong Informational - Expires April 2004 14 LEMONADE Goals October 2003 6. Issues and Requirements: TUI subset of WUI 6.1. Requirements on the Message Retrieval protocol IMAP is the Internet protocol for rich message retrieval and manipulation. The project will extend IMAP where necessary and will not create a new protocol. 6.1.1. Performance Issues 6.1.1.1. Real-Time Playback The real-time playback of a voice message MUST be supported so that the user experience does not differ noticeably from that of a conventional voice messaging system. Possible solutions for this include making use of the existing incremental download capability of the IMAP protocol, or utilizing an companion streaming protocol. The IMAP protocol itself does not provide streaming in the strict definition of the term. It does provide for the incremental download of content in blocks. Most IMAP clients do not support this behavior and instead download the entire contents into a temporary file to be passed to the application. There are several approaches to achieve real-time playback. The first approach is to implement an IMAP client that can pass data incrementally to the application as it is received from the network. The application can then read bytes from the network as needed to maintain a play buffer and not require the full download of contents. This approach may require server- side development to efficiently support partial download. (i.e. to avoid re- opening files and seeking to requested pointer) Alternatively, the client can use the proposed IMAP channel extension to request that the server make the selected content available via an alternate transport mechanism. A client can then ask the server to make the voice data available to the client via a streaming media protocol such as RTSP. This requires support on the client and server of a common streaming protocol. 6.1.1.2. Avoid Base-64 Data Inflation Another important performance optimization is enabling the transport of data using more efficient native coding rather than the text-like "base 64" encoding. Standard IMAP4 uses a text-based data representation scheme where all data is represented in a form that looks like text, that is, voice data must be encoded using "base 64" into a transport encoding that adds 30% to the size of a message. When downloading or appending messages to the server, substantial additional bandwidth is utilized. Wong Informational - Expires April 2004 15 LEMONADE Goals October 2003 Proposed Solutions: Where IMAP channel is appropriate, the external channel may be binary capable; that is, the external access may not require re-encoding. Such mechanisms as HTTP, FTP, or RTSP are available for this download. The IMAP binary extension standards proposal extends the IMAP fetch command to retrieve data in the binary form. This is especially useful for large attachments and other binary components. Binary in conjunction with a streaming client implementation may be an attractive alternative to the channel extension. 6.1.2. Functional Issues 6.1.2.1. Mailbox Summary Support The common TUI prompt, "you have two new voice messages, six unheard messages, and one new fax message" requires more information than is conveniently made available by current message retrieval protocols. The existing IMAP protocol's mailbox status command does not include a count by message context. A possible solution is have the mail server keep track of these current counters and provide a status command that returns an arbitrary mailbox summary. The IMAP status command provides a count of new and total messages with standardized attributes extracted from the message headers. This pre-determined information does not currently include information about the message type. Without additional conventions to the status command, a client would have to download the header for each message to determine its type, a prohibitive cost where latency or bandwidth constraints exist. 6.1.2.2. Sort by Message Context Support This functionality is required to present new voice messages first and then new fax messages within a single logical queue as voice mailboxes commonly do. Again this is a question of convenience and performance. Adequate performance may only be possible if the mail server provides a sort by context or maintains a set of virtual mailboxes (folders) corresponding to message types as for Mailbox Summary Support. IMAP does not support this directly. A straightforward solution is to define an extensible sort mechanism for sorting on arbitrary header contents. 6.1.2.3. Status of Multiple Mailboxes Support Extension mailbox support requires the ability to efficiently status a mailbox other than the one currently logged into. This facility is required to support sub-mailboxes, where a common feature is to check whether other sub-mailboxes in the same family group have new messages. Current mechanisms are limited to logging into each of set of mailboxes, checking status, logging out, and repeating until all sub-mailboxes are used. Wong Informational - Expires April 2004 16 LEMONADE Goals October 2003 6.1.2.4. Specialized Mailbox Support Applications that provide features such as check receipt, deleted message recovery, resave, and others require the ability to access messages in pre- determined mailboxes with specific behaviors. (E.g. Outbox, Sent Items, Delete Items, Expired items, Drafts) IMAP provides only a single standardized folder, the inbox. This functionality does not require new protocol per-se, but standardized usage and naming conventions necessary for interoperability. It required that the server provide the underlying logic to support these special folders including automatic insertion, scheduled copying, and periodic deletion. 6.1.2.5. CLID Restriction indication/preservation Many calling features are dependent upon collected caller-ID information. Trusted clients such as the TUI, and other service supporting user agents such as WEB and WAP servers may have access to restricted caller-ID information for such purposes as callback. Untrusted clients must not receive this information. A mechanism for communicating "trust" between the client and the server is required to deliver this information to the end-user when appropriate. Further, when sending messages between servers within a network, a means of communicating trust is needed such that the identity of the sender can be preserved for record-keeping and certain features while ensuring the identity is not disclosed to the recipient in inappropriate ways. 6.1.2.6. Support for Multiple Access to Mailbox If the telephone answering application client uses IMAP4 for greeting access and message deposit, it is essential that the server provide support for simultaneous login. It is common in voicemail for an incoming call to be serviced by the telephone answering application client at the same time the subscribers is logged into their mailbox. Further, new applications such as WEB and WAP access to voicemail may entail simultaneous login sessions, one from the TUI client and one from the visual client. The existing standard does not preclude multiple accesses to a mailbox, but it does not explicitly require support of the practice. The lack of explicit support requires the server and client to adhere to a common set of practices and behaviors to avoid undesirable and unpredictable behaviors. RFC 2180 describes a candidate set of conventions necessary to support this multiple-access technique. It is not a standard. 6.2. Requirements on the Message Submission Protocol 6.2.1. Forward without Download Support It is common to forward messages, or to reply to messages with a copy of the attached content. Today such forwarding requires the sender to download a complete copy of the original message, attach it to the reply or forward message, and resubmit the result. For large messages, this Wong Informational - Expires April 2004 17 LEMONADE Goals October 2003 represents a substantial amount of bandwidth and processing. For clients connected via long-thin pipes, alternatives are REQUIRED. One approach is to define an extension to message submission to request the submission server to resolve embedded URL's within a message before relaying the message to the final destination. 6.2.2. Quota by Context Enforcement It is common in a unified messaging system to offer separate quotas for each of several message contexts to avoid the condition where a flood of email fills the mailbox and prevents the subscriber from receiving voice messages via the telephone. It is necessary to extend the protocols to support the reporting of the "mailbox full" status based on the context of the submitted message. Clear security issues are involved to prevent the misidentification of a message context for the purpose of intentionally filling a subscribers mailbox. It is envisioned that the message submission protocol will support authentication of trusted submission agents authorized to submit distinguished messages. Voice mail system mailboxes commonly contain voice and fax messages. Sometimes, such systems also support email messages (text, text with attachments, and multimedia messages) in addition to voice messages. Similarly to the requirement for sort by message context -- quota management is also required per message context. One possible use-case is the prevention of multiple (large) messages of one type (e.g. email messages) from consuming all available quota so that messages of another type (e.g. voice or fax messages) cannot be further deposited to the mailbox. This work effort should define a mechanism whereby a trusted client can declare the context of a message for the purpose of utilizing a protected quota. This may by extensions to the SMTP-submit or LMTP protocols. 6.2.3. Future Delivery Support with Cancel Traditionally messages sent with "future delivery" are held in the recipients client "outbox" or equivalent until the appointed submission time. Thin clients used with TUIs do not have such persistent storage or may be intermittently connected and must rely upon server-based outbox queues. Such support requires extensions to message submission protocols to identify a message as requiring queuing for future delivery. Extensions to IMAP4 or conventions are required to view and manipulate the outbound queue, for such purposes as canceling a future message. Server support for managing such a queue is required such that messages are sent when they are intended. Wong Informational - Expires April 2004 18 LEMONADE Goals October 2003 6.2.4. Support for Committed Message Delivery Voice messaging service has provided a high degree of reliability and performance for telephone answering messages. The expectation is that once the caller has hung-up, the messages is in the mailbox and available for review. The traditional Internet mail architecture suggests these messages should be sent to the mailbox via SMTP. This approach has two limitations. The first and most manageable is that the message forwarding may take more time than is tolerable by the subscriber. The second is that the message may fail to be delivered to the mailbox, and because there is no way to return notice to the caller that the message is "lost". The standards community is working on an alternative to SMTP called Local Message Transport Protocol(LMTP). This protocol addresses a number of limitations in SMTP when used to provide atomic delivery to a mailbox. The failure modes in this proposal are carefully controlled, as are issues of per-message quota enforcement and message storage quota-override for designated administrative messages. An alternative approach is to misuse the IMAP protocol slightly and use an IMAP based submission mechanism to deposit a message directly into the recipient's inbox. This append must be done by a special super-user with write permissions into the recipient mailbox. Further, the message store must be able to trigger notification events upon insertion of a message into the mailbox via the Append command. The historic limitation on using IMAP4 for message sending involves the inability of IMAP to communicate a full SMTP envelope. For telephone answering, these limitations are not significant. 6.3. Requirements on Message Notification Voicemail systems traditionally notify subscribers of certain events happening in their mailbox. For example, it is common to send an SMS, or a pager notification for new message arrival, when messages have been read (and are not considered "new" anymore), mailbox full etc. When implemented over IMAP-based message stores, voice mail system need to be notified about these events. Furthermore, when other applications are accessing/manipulating the mailbox, it is desirable that a notification component (which is sometimes part of the voicemail application) gets notifications from the message store about these events, so that it can produce the desired user notification. The standards community is working on a standard for "Simple Notification and Alarm Protocol (SNAP)" that defines the expected behavior of the message store for various events, much of them triggered by IMAP commands. 6.3.1. Additional Requirements on Message Notification A format for message notifications for servers reporting status information to other servers (e.g. IMAP4 server to SMS or pager server) MUST be defined. The method for delivery of these notifications MUST also be specified. Wong Informational - Expires April 2004 19 LEMONADE Goals October 2003 The design for this MUST take into account the IAB general guidelines for notification services(TBD). Wong Informational - Expires April 2004 20 LEMONADE Goals October 2003 7. Issues and Requirements: WUI Mobility Aspects 7.1. Wireless Considerations on Email 7.1.1. Transport Considerations Compared to a LAN/WAN configuration or even to a wire-line dial-up connection, the probability of an interruption to a wireless connection is very high. Interruptions can be due to hand-off, signal fading, or stepping beyond cell coverage. In addition, since the mobile handset is also used for other types of communications, there is relatively high probability that the data session will be interrupted either by incoming voice calls or by "pushed" messages from services such as SMS, MMS and WAP. It is also common in these environments that the device's IP address change within a session. 7.1.2. Handset-Resident Client Limitations Although the capabilities of wireless handsets are rapidly improving, the wireless handset remains limited in its capability to host email clients. Currently, email access is restricted to only high-end wireless handsets. These limitations include: o Client size Handset-resident clients are limited in size because either the handset has limited storage space or the handset vendor/network operator has set a limit on the size of client application that can reside on the handset. o Runtime memory Wireless handsets have limited runtime memory for the use of the mobile email client. o CPU Speed Wireless handsets have CPUs that are inferior to those in conventional systems (PCs) that run email clients. o User Interface Handsets have very limited input and output capabilities. Most of them do not have a keyboard or a pointing device. 7.1.3. Wireless Bandwidth and Network Utilization Considerations 7.1.3.1. Low Bandwidth 2G mobile networks enabled wireless data communications but only at very low bandwidths using circuit-switched data. 2.5G and 3G networks improve on this. However, existing email clients require very large (up to several Wong Informational - Expires April 2004 21 LEMONADE Goals October 2003 MBs) files -- encountered in multi-media attachments such as presentations, images and documents -- to be downloaded even though mobiles can not exploit most of the data (because of color depth and screen size limitations). Transferring such large files over the air is of questionable value even when higher wireless bandwidth is available. 7.1.3.2. Price Awareness In many cases, users of mobile data services are charged by the amount of data (e.g. kilobytes) downloaded to the handset. Most users currently experience a higher per-kilobyte data charge with a wireless service than over a wire-line service. Users are sensitive to the premium for wireless service. This results in an unwillingness to download large amounts of unnecessary data to the handset and the desire to be able to download only selected content. 7.1.3.3. File Size Limitations In some cases, the size of file -- that can be transmitted over the air to the handset -- is limited. 7.1.4. Content Display Considerations 7.1.4.1. Display Size and capabilities Wireless terminals are currently limited in their display size, color depth, and ability to present multimedia elements (i.e. if multiple pictures are sent, the mobile can usually present only one reduced-sized picture element at a time rather than the several picture elements at once in the same display that a conventional PC email client would be able to show). Therefore many email attachments destined for a mobile may require changes in size, color depth and presentation method to be suitably displayed. 7.1.4.2. Supported Media Formats Wireless handsets can only display a limited set of media format types. While PC clients support a large variety of document types (and allow on- demand "codec"/player download), mobiles have very limited support. (e.g., most only support WAV audio and cannot play other formats such as AU, MP3 and AIFF.) Furthermore, although almost all new handsets sold today can display images and sound in some advanced format, support for displaying other media or application-specific formats, such as MS-Office (TM) and Acrobat PDF documents is not expected to be widespread in the near future. 7.1.4.3. Handset Type Variety As mentioned above, there are many handset types available in the market and each has different display capabilities, screen characteristics and processing capabilities. The mobile email service SHOULD be able to support as many handset types as possible. Wong Informational - Expires April 2004 22 LEMONADE Goals October 2003 7.1.4.4. Specific Attachment Display Scenarios Handsets are unsuited for perusing entire lengthy documents or presentations. A mobile user is more likely to look at several pages of a document or several slides of a presentation and then take action accordingly (e.g., forward the email message to another recipient, print it, or leave the document for later retrieval from another device) rather than go through the whole document. Therefore, there is a need to enable users to download not the entire attachment but rather just a selected PART of it. (e.g., users SHOULD be able to download the "Table of Contents" of a document; to search within a document; to download the first slide of a presentation; the next slide of this presentation; a range of slides, etc.) 7.2. Requirements to Enable Wireless Device Support The following requirements are derived from the considerations mentioned above. 7.2.1. Transport Requirements The mobile email protocol MUST anticipate transient losses of connectivity and allow clients to quickly and easily recover (restore state) from interrupted connections. IMAP4 Context An IMAP4 connection requires the communication socket to remain up continuously during an email session. In case of transient loss of communications, the connection must be reestablished. It is up to the client to reconnect to the server and return to an equivalent state in the session. This overhead of restoring connections is very costly in response time and additional data transmission. 7.2.2. Enhanced Mobile Email Functionality 7.2.2.1. Forward Without Fetch To minimize the downloading of data over the air, the user MUST be able to forward a message without initially downloading it entirely or at all to the handset. The mobile email protocol MUST support the ability to forward a message without retrieving it. This requirement is identical to the TUI requirement that is described in section 6.2.1 Wong Informational - Expires April 2004 23 LEMONADE Goals October 2003 7.2.2.2. Media Streaming The mobile email protocol MUST provide a solution that will enable media streaming to the wireless handset. This requirement is similar to the TUI requirement that is described in section 6.1.1.1 7.2.3. Client Requirements IMAP4 clients are large because IMAP4 already consists of a complex set of functions (e.g., parsing of a broad variety of MIME formats). The mobile email client SHOULD be: (1) Small in size (2) Efficient in CPU consumption (3) Efficient in runtime memory consumption To enable such extremely thin clients, in developing the mobile email protocol we SHOULD consider simplifying the IMAP functionality that handsets need support. 7.2.4. Bandwidth Requirements The mobile email solution SHOULD minimize the amount of data transmitted over the air. One way of pursuing this goal is the use of content transcoding and media adaptation by the server before message retrieval in order to optimize it for the capabilities of the receiving handset. Another possible optimization is to make the mobile email protocol itself simple containing as little overhead as possible. A third approach is to minimize the bandwidth usage as described in section [6.1.1.2], "Avoid Base-64 Data Inflation". 7.2.5. Media Handling Requirements As described above, wireless devices have limited ability to handle media. Therefore, the server may be have to perform media manipulation activities to enable the terminal to display the data usefully. 7.2.5.1. Device Capabilities Negotiation In order to correctly support the different characteristics and capabilities of the various handset types available in the market, the mobile email protocol MUST include provision for email content adaptation. For example, the choice of supported file formats, color depth and screen size. Work on ESMTP transcoding [CONNEG] may address this issue. 7.2.5.2. Adjusting Message Attachments for Handset Abilities To support wireless handsets, the server could transcode the message attachments into a representation that is more suitable for that device. This behavior should be based on the device capabilities negotiation as Wong Informational - Expires April 2004 24 LEMONADE Goals October 2003 described in [7.2.5.1]. For example, a device that cannot display GIF format but only WBMP should get a WBMP image. Devices that cannot display a PDF file should get a text version of the file. The handset should control what or any transcoding is desired. It should be able to retrieve the original attachment without any changes. In addition, the device should be able to choose between "flavors" of the transcoding ("Present the content as thumbnail image" is an example of such a specific media manipulation.) Again work on ESMTP transcoding [CONNEG] may address this issue. 7.2.5.3. Handling Attachment Parts A desirable feature to have (but out of scope for the current lemonade charter) is the following: To enable users to retrieve not only the entire attachment file but also parts of it, the mobile email protocol should include the ability for the retrieving client to specify selected elements of an attachment for download. Such elements can be, for example, specific pages of a document, the "table of contents" of a document or specific slides of a presentation. Wong Informational - Expires April 2004 25 LEMONADE Goals October 2003 8. Interoperation with Existing Mobile Messaging LEMONADE's charter includes the specification of how enhanced Internet Mail will interoperate with existing mobile messaging services (e.g. MMS) to deliver messages to mobile clients. 8.1. Addressing of mobile devices E.164 addressing is prevalent in mobile messaging services to address recipient mobiles. Consideration should be given to supporting E.164 addressing for mobile devices in addition to RFC822 addressing. 8.2. Push model of Message Retrieval MMS provides a push option for message retrieval. The option hides network latencies and reduces the need for user-handheld interaction. If a level of support for mobiles comparable MMS is desired, this mode of operation should be considered. 8.3. Operator Issues 8.3.1. Support for end-to-end delivery reports and read reports Support for committed delivery is described in [6.2.4] but this is different. 8.3.2. Support for Selective Downloading Especially important, if a push model of message retrieval is supported, is the need for selective downloading and SPAM control. 8.3.3. Transactions and Operator Charging Units Mobile network providers often operate on a "pay for use" service model. This brings in requirements for clearly delineated service transactions that can be reported to billing systems, and for positive end-to-end acknowledgement of delivery or non-delivery of messages already mentioned [8.3.1]. 8.3.4. Network Authentication Some mobile networks support network authentication as well as application authentication. Wong Informational - Expires April 2004 26 LEMONADE Goals October 2003 9. Informative References [RFC2026] Bradner, S., "The Internet Standards Process -- Revision 3", BCP 9, RFC 2026, October 1996. [RFC2119] 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", RFC 822 (obsolete), August 1982 [RFC1891] Moore, K. "SMTP Service Extension for Delivery Status Notifications", RFC 1891, January 1996. [RFC1939] Myers, J., Rose, M. "Post Office Protocol - Version 3", RFC1939, May 1996 - also STD:53 [RFC2045] Freed, N. and Borenstein, N. "Multipurpose Internet Mail Extensions (MIME) Part One: Format of Internet Message Bodies", RFC2045, November 1996 [RFC2046] Freed, N. and Borenstein, N. "Multipurpose Internet Mail Extensions (MIME) Part Two: Media Types", RFC2046, November 1996 [RFC2047] Moore, K. "Multipurpose Internet Mail Extensions (MIME) Part Three: Message Header Extensions for Non-ASCII Text", RFC2047, November 1996 [RFC2048] Freed, N., Klensin, J., and Postel, J. "Multipurpose Internet Mail Extensions (MIME) Part Four: Registration Procedures", RFC2048, November 1996 [RFC2049] Freed, N. and Borenstein, N. "Multipurpose Internet Mail Extensions (MIME) Part Five: Conformance Criteria and Examples", RFC2049, November 1996 [RFC2060] Crispin, M. "INTERNET MESSAGE ACCESS PROTOCOL - VERSION 4rev1", RFC2060, December 1996 [RFC2086] Myers, J. "IMAP4 ACL extension" January 1997. (Status: PROPOSED STANDARD) [RFC2087] Myers, J. "IMAP4 QUOTA extension" January 1997. (Status: PROPOSED STANDARD) [RFC2221] Gahrns, M. IMAP4 Login Referrals. October 1997. (Status: PROPOSED STANDARD) [RFC2298] R. Fajman, "An Extensible Message Format for Message Disposition Notifications", RFC 2298, March 1998. [RFC2421] Vaudreuil, G., Parsons, G. "Voice Profile for Internet Mail - version 2", RFC2421, September 1998 Wong Informational - Expires April 2004 27 LEMONADE Goals October 2003 [RFC2422] Vaudreuil, G., Parsons, G. "Toll Quality Voice - 32 kbit/s ADPCM MIME Sub-type Registration", RFC2422, September 1998 [RFC2423] Vaudreuil, G., Parsons, G. "VPIM Voice Message MIME Sub-type Registration", RFC2423, September 1998 [RFC2424] Vaudreuil, G., Parsons, G. "Content Duration MIME Header Definition", RFC2424, September 1998 [RFC2301] McIntyre, L., Zilles, S., Buckley, R., Venable, D., Parsons, G., Rafferty, J. "File Format for Internet Fax", RFC2301, March 1998 [RFC2302] Parsons, G., Rafferty, J. Zilles, S. "Tag Image File Format (TIFF) - image/tiff MIME Sub-type Registration", RFC2302, March 1998 [RFC2303] Allocchio, C. "Minimal PSTN address format in Internet Mail", RFC 2303, March 1998 [RFC2304] Allocchio, C. "Minimal FAX address format in Internet Mail", RFC2304, March 1998 [RFC2305] Toyoda, K., Ohno, H., Murai, J., Wing, D. "A Simple Mode of Facsimile Using Internet Mail", RFC2305, March 1998 [RFC2306] Parsons, G., Rafferty, J. "Tag Image File Format (TIFF) - F Profile for Facsimile", RFC2306, March 1998 [RFC2476] Gellens, R. and Klensin J. "Message Submission", December 1998. (Status: PROPOSED STANDARD) [RFC2532] Masinter, L. and Wing, D., "Extended Facsimile Using Internet Mail", RFC 2532, March 1999 [RFC2616] Fielding, Gettys, Berners-Lee, et. al., "Hypertext Transfer Protocol - HTTP 1.1", RFC 2616, June 1999. [RFC2821] Klensin, J., Editor " Simple Mail Transfer Protocol", RFC 2821, April 2001 [RFC2822] Resnick, P., Editor "Internet Message Format", RFC 2822, April 2001. [RFC3458] Burger, E., Candell, E., Eliot, C., and Klyne, G., "Message Context for Internet Mail", January 2003. [RFC3459] Burger, E., "Critical Content Multi-purpose Internet Mail Extensions (MIME) Parameter", January 2003. [BIN] "IMAP4 Binary Content Extension", 01/18/2002, , work in progress [CHAN] "IMAP4 Channel Transport Mechanism", 11/27/2001, , work in progress Wong Informational - Expires April 2004 28 LEMONADE Goals October 2003 [CONNEG] Toyoda, K. and Crocker, D., "SMTP Service Extensions for Fax Content Negotiation", DRAFT-FAX-ESMTP-CONNEG-06.TXT, February 2003, work in progress. [IVM] McRae, S. and Parsons, G., "Internet Voice Messaging", draft-ietf-vpim-ivm-04.txt, work in progress [LMTP] "LMTP Service Extension for Ignoring Recipient Quotas", 08/30/2001, , work in progress [MMS] Leuca, I. "Multimedia Messaging Service", Presentation to the VPIM WG, IETF53 Proceedings, April 11, 2002 [SIPMWI] Mahy, R. "A Message Summary and Message Waiting Indication Event Package for the Session Initiation Protocol (SIP)", draft-ietf-sipping-mwi- 01.txt [SNAP] Shapira, N. and Aloni, E. "Simple Notification and Alarm Protocol (SNAP)",, 12/20/2001, work in progress [UMISS] Vaudreuil, Greg "Messaging profile for telephone-based Messaging clients", , February 2002 [UMREQS] Burger, E, "Internet Unified Messaging Requirements", , February 2002 [OMAMMS] Open Mobile Alliance (OMA) "Multimedia Messaging Service; Architectural Overview Version 1.1", OMA, 2002 [OMAWAPPUSHO] Open Mobile Alliance (OMA) "Push Architectural Overview, WAP- 250-PushArchOverview-20010703-a", OMA, 2001 [OMAWAPPUSHA]Open Mobile Alliance (OMA) "Push Architectural Overview Push Access Protocol Specification, WAP-247 PAP - -20010429-a", OMA, 2001 [OMAPUSHPROX] Open Mobile Alliance (OMA) "Push Proxy Gateway Service Specification", WAP-249-PPGService-20010425.pdf, OMA, 2001 [OMAMMSC] Open Mobile Alliance (OMA) "Multimedia Messaging Service; Client Transactions Version 1.1", OMA-MMS-v1_1, OMA, 2002 [OMAMMSEP] Open Mobile Alliance (OMA) "Multimedia Messaging Service; Encapsulation Protocol Version 1.1", OMA-MMS-v1_1, OMA, 2002 [OMAUAF] Open Mobile Alliance (OMA) "User Agent Profile, Version 1.1", OMA- UAPROF-v1_1, OMA, December 2002. [OMANOTIF] Open Mobile Alliance (OMA) "Email Notification Version 1.0", OMA, 2002 [3GPPMMS1] 3GPP TS 22.140 "Third Generation Partnership Project; Technical Specification Group Services and System Aspects; Service aspects; Functional description; Stage 1 Multimedia Messaging Service", 3GPP, 2001 Wong Informational - Expires April 2004 29 LEMONADE Goals October 2003 [3GPPMMS2] 3GPP TS 23.140 "Third Generation Partnership Project; Technical Specification Group Terminals; Multimedia Messaging Service (MMS); Functional description; Stage 2", 3GPP, 2001 [SMS] C.S0015-A: Short Message Service (SMS), December 1999, 3GPP2. [EMS] S.R0051-0 v1.0: "Enhanced Message Service (EMS) Stage 1 Description", 3GPP2, July 2001. [CCITTQ700] CCITT White Book, Volume VI, Fascicle VI.7, Recommendations Q.700-Q.716: Specifications of Signalling System No. 7. [CCITTQ721] CCITT White Book, Volume VI, Fascicle VI.8, Recommendations Q.721-Q.766: Specifications of Signalling System No.7. [ITUE164] ITU-T Recommendations Series E: "E.164: The international public telecommunication numbering plan"; ITU, May 1997. [ITUQ763] ITU White Book, ITU-T Recommendation Q.763: Specifications of Signalling System Number 7. [ITUX25] ITU-T Recommendation Series X: X.25: "Interface between Data Terminal Equipment (DTE) and Data Circuit-terminating Equipment (DCE) for terminals operating in the packet mode and connected to public data networks by dedicated circuit", ITU, Oct 1996. [GRSS7] GR-246-CORE, Issue 1, December 1994: Specifications of Signalling System Number 7. Wong Informational - Expires April 2004 30 LEMONADE Goals October 2003 10. Acknowledgments Ari Erev and Noam Shapira contributed substantial requirements for IMAP to support a telephone-based (TUI) messaging client. Meir Mendelovich (Comverse) helped in merging the wireless requirements section. Benjamin Ellsworth (Openwave) contributed to mobile messaging architectures and requirements. Wong Informational - Expires April 2004 31 LEMONADE Goals October 2003 11. Editor's Address Jin Kue Wong Nortel Networks P.O. Box 3511, Station C Ottawa, ON K1Y 4H7 Canada Phone: +1-613-763-2515 Email: jkwong@nortelnetworks.com Wong Informational - Expires April 2004 32 LEMONADE Goals October 2003 12. Contributors's Addresses Eric Burger SnowShore Networks, Inc. 285 Billerica Rd. Chelmsford, MA 01824-4120 USA Phone: +1 978/367-8400 Email: e.burger@ieee.org Yair Grosu Comverse 29 Habarzel St. Tel-Aviv 69710 Israel Email: Yair.Grosu@comverse.com Glenn Parsons Nortel Networks P.O. Box 3511, Station C Ottawa, ON K1Y 4H7 Canada Phone: +1-613-763-7582 Email: gparsons@nortelnetworks.com Milt Roselinsky Openwave Systems, Inc. 530 E. Montecito St. Santa Barbara, CA 93103 Phone: 805-884-6207 Email: milt.roselinsky@openwave.com Dan Shoshani Comverse 29 Habarzel St. Tel-Aviv 69710 Israel Email: Dan.Shoshani@comverse.com Alan K. Stebbens Openwave Systems, Inc. 530 E. Montecito St. Santa Barbara, CA 93103 Phone: 805-884-3162 Email: alan.stebbens@openwave.com Gregory M. Vaudreuil Lucent Technologies 7291 Williamson Rd. Dallas, TX 75214 United States Phone/Fax: +1-214-823-9325 Email: GregV@ieee.org Wong Informational - Expires April 2004 33 LEMONADE Goals October 2003 Full Copyright Statement Copyright (C) The Internet Society (2003). All Rights Reserved. This document and translations of it may be copied and furnished to others, and derivative works that comment on or otherwise explain it or assist in its implementation may be prepared, copied, published and distributed, in whole or in part, without restriction of any kind, provided that the above copyright notice and this paragraph are included on all such copies and derivative works. However, this document itself may not be modified in any way, such as by removing the copyright notice or references to the Internet Society or other Internet organizations, except as needed for the purpose of developing Internet standards in which case the procedures for copyrights defined in the Internet Standards process must be followed, or as required to translate it into languages other than English. The limited permissions granted above are perpetual and will not be revoked by the Internet Society or its successors or assigns. This document and the information contained herein is provided on an "AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. Acknowledgement The Internet Society currently provides funding for the RFC Editor function. Wong Informational - Expires April 2004 34