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     Internet Draft                                       Greg Vaudreuil
     Expires in six months                           Lucent Technologies
                                                       February 28, 2003
                         Voice Message Routing Service
  Status of this Memo
     This document is an Internet-Draft and is in full conformance with all
     provisions of Section 10 of RFC2026.
     This document is an Internet Draft.  Internet Drafts are working
     documents of the Internet Engineering Task Force (IETF), its Areas,
     and its Working Groups.  Note that other groups may also distribute
     working documents as Internet Drafts.
     Internet Drafts are valid for a maximum of six months and may be
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     ftp.isi.edu (US West Coast).
  Copyright Notice
     Copyright (C) The Internet Society (2003).  All Rights Reserved.
     This Internet-Draft is in conformance with Section 10 of RFC2026.
     Voice messaging is traditionally addressed using telephone number
     addressing. This document describes two techniques for routing voice
     messages based on a telephone number.  The VPIM Directory service
     provides a directory mechanism to lookup a VPIM email address with a
     telephone number and confirm that the address is both valid and the
     associated with the intended recipient.  However this service will
     take time become widely deployed in the nearest term.  This document
     also describes a more limited send-and-pray service useful simply to
     route and deliver messages using only the ENUM telephone number
     resolution service and the existing DNS mail routing facilies.
     Please send comments on this document to the VPIM working group
     mailing list <vpim@lists.neystadt.org>

     Internet Draft            VPIM Routing            February 28, 2003
  Working Group Summary
     This is a submission to the IETF VPIM working group.
  Table of Contents
  1.   ABSTRACT ..........................................................3
  2.   DESIGN GOALS ......................................................3
  3.   THE COMPLETE SERVICE ..............................................4
    3.1  Specification of Service "E2U+Voice:DIR" ........................4
    3.2  VPIM Directory Discovery ........................................4
    3.3  Address Query ...................................................5
  4.   THE BASIC SERVICE .................................................6
    4.1  Specification of Service "E2U+VPIM:Mailto:" .....................6
    4.2  Address Construction ............................................7
    4.3  Interdomain Message Routing .....................................7
    4.4  Intradomain Message Routing .....................................7
  5.   SECURITY CONSIDERATIONS ...........................................9
  6.   REFERENCES ........................................................9
  7.   COPYRIGHT NOTICE ..................................................9
  8.   AUTHORS' ADDRESSES ...............................................10
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  1. Abstract
  2. Design Goals
     This profile is intended to provide a range of functional capabilities
     for message routing based on one of two mechanisms.  The most complete
     service should use the ENUM address resolution service to determine
     the VPIM directory, and then use LDAP to retreive the VPIM-specific
     email address to use for message routing.
     The more basic send-and-pray message service uses only the ENUM
     service and MX records to route the message to the intended
     recipient's domain.  The intelligence to further route the message to
     the intended recipient is placed within the message routing system of
     the recipient's domain.
     The basic mechanism may be used even when there is a VPIM directory
     service avaiable.  The basic service is useful when LDAP queries are
     not available, such as may be the case for disconnected mobile
     terminals or because of firewall or information security policies.
     The basic mechanism should facilitate the routing of VPIM messages to
     a suitable internal destination with a minimum of configuration.  It
     is an important goal to avoid any content-processing to determine the
     nature of the message and its internal destination.  It should be
     possible at a minimum to establish a simple mail forwarding rule to
     send all inbound VPIM messages to a designated system while
     facilitating the routing of FAX, SMS, or other telephone-addressed
     messages to other potentially different systems.
     It is a goal that the mechanisms outlined in this document be
     extensible for all store-and-forward, telephone-number addressed
     messaging services.
     It is a goal that the VPIM directory discovery and VPIM directory
     query steps occur within the timing constraints for user interfaces in
     PSTN networks.  In general, that constraint can be generalized to be a
     two-second response 95% of the time.
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  3. The Complete Service
     For the complete VPIM message routing service, the sending client
     SHOULD query the VPIM directory for the VPIM-specific email address.
     The client SHOULD use the ENUM service to retrieve the identity of the
     VPIM Directory to query.  The client should then query that server for
     the email address and any additional attributes desired.
  3.1 Specification of Service "E2U+Voice:DIR"
        * Service Name: E.164 to VPIM LDAP URL
        * URI Type: "LDAP:"
        * SubTyoe: Voice
        * Functional Specification: See section 3.2 through 3.3
        * Intended Usage: COMMON
        * Author: Greg Vaudreuil (gregv@ieee.org)
        * Security Considerations:
          o Malicious Redirection
              One of the fundamental dangers related to any service such
              as this is that a malicious entry in a resolver's database
              will cause clients to resolve the E.164 into the wrong URL.
              The possible intent may be to cause the client to retrieve a
              resource containing fraudulent or damaging material.
          o Denial of Service
              By removing the URL to which the E.164 maps, a malicious
              intruder may remove the client's ability to access the
  3.2 VPIM Directory Discovery
     The VPIM directory server is found by using the ENUM protocol and
     querying for the VPIMDIR service associated with the telephone number
     of the recipient.
     The DNS query name is created as described by [ENUM].  The telephone
     number used for the directory location MAY contain additional sub-
     address information as additional digits.
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              IN NAPTR  10 10 "U" "E2U+voice:DIR" \
                   "$!ldap://vpimdir1.Zcorp.com/telephoneNumber=\1!" .
              IN NAPTR  10 20 "U" " E2U+Voice:DIR" \
                   "$!ldap://vpimdir2.Zcorp.com/telephoneNumber=\1!" .
     It is RECOMMENDED that VPIMDIR servers be deployed in a redundant
     configuration.  NAPTR weight fields provide the ability to give two
     records indicating the same service and preference a different weight.
     The same weight can be specified for random distribution between the
     two servers. See [NAPTR]
  3.3 Address Query
     Once the VPIM directory is discovered, the client SHOULD issue a LDAP
     query for the vPIMrFC822Mailbox That is, the address that SHOULD be
     used as the value for both the RFC822 To: field and the SMTP RCPT
     command. See [VPIMDIR]
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  4. The Basic Service
     The basic service relies upon NAPTR rewrite rules to mechanically
     construct a valid VPIM-specific email address.  In the recipient's
     domain, the constructed address may be further routed using
     intradomain mail routing techniques such as those defined in [LASER].
     To facilitate a full range of intradomain routing options, the
     constructed email address indicates that the message is a VPIM
     message.  For ease of processing in the recipient's intradomain mail
     routing system, the indication that the message is a VPIM message
     SHOULD be in the domain name portion.
     Note, that no validation that the constructed address is valid, nor
     that the constructed address corresponds to the intended recipient.
     Because no capabilities information is provided about the recipient,
     messages sent with this mechaism SHOULD be sent using only the media
     and content types of the VPIM V2 profile.
  4.1 Specification of Service "E2U+VPIM:Mailto:"
        * Service Name: E.164 to VPIM MailTo: URL
        * URI Type: "Mailto:"
        * SubTyoe: VPIM
        * Functional Specification: See section 4.2 through 4.4
        * Intended Usage: COMMON
        * Author: Greg Vaudreuil (gregv@ieee.org)
        * Error Conditions:
          o E.164 number not in the numbering plan
          o E.164 number in the numbering plan, but no URLs exist for
                that number
          o E2U+VPIM:Mailto Service unavailable
        * Security Considerations:
          o Malicious Redirection
              One of the fundamental dangers related to any service such
              as this is that a malicious entry in a resolver's database
              will cause clients to resolve the E.164 into the wrong URL.
              The possible intent may be to cause the client to retrieve a
              resource containing fraudulent or damaging material.
          o Denial of Service
              By removing the URL to which the E.164 maps, a malicious
              intruder may remove the client's ability to access the
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          o Unsolicited Bulk Email
              The exposure of email addresses through the ENUM service
              provides a bulk mailer access to large numbers of email
              addresses where only the telephone number was previously
  4.2 Address Construction
     Construct an VPIM email address using the address rewrite rules of the
     NAPTR records associated with the VPIM service.
  4.3 Interdomain Message Routing
     The interdomain routing of a constructed VPIM address is mechanically
     indistinguishable from existing email routing.  No changes to the
     infrastructure are required.  The sending system consults the Domain
     Name System for an MX record corresponding to the domain name and
     forwards the message to the indicated system.
  4.4 Intradomain Message Routing
     Within the recipient's domain, the message may be further routed to
     the appropriate messaging system. Two general mechanisms may be used
     to further route the message to the intended system within a network.
          Note: This section is strictly informational.  The mechanisms
          for intradomain routing are an internal matter for the domain
          and do not affect the protocol.  It is only necessary that the
          addresses created by the NAPTR rewrite rules have meaning to the
          domain advertising them.  However, a convention for the creation
          and use of such address may be useful.
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  4.4.1  Directory-Enabled Routing
     Various proprietary directory mechanisms provide a means for an
     inbound mail router of the recipient's domain to send a message to the
     appropriate internal mail host.  In many cases, the local part of the
     address is used to query for an internal mail address.  That internal
     mail address is substituted for the SMTP RCPT address and used to
     deliver the message to the recipient mailbox.  Note that the mailbox
     does not need to have any knowledge of the mechanically-constructed
     telephone number-based address.
                 Example address: +12145551212@sp.net
  4.4.2 Service-based Mail Routing
     Alternately, a mail gateway may simply send all voice messages into a
     separate messaging system.  That system may be a single voice
     messaging server or a service-specific gateway into a larger
     telephonenumber-based voice-messaging network.
     Such a mail gateway may be provisioned with a simple rule or small set
     of rules to forward all messages of a given service type to a pre-
     defined server.  This rule would check for the service name "VPIM" as
     a prefix to the constructed domain name to reroute messages.
                 Example address: +12145551212@VPIM.sp.net
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  5. Security Considerations
     There is little information disclosed to the sender of a message that
     is not already disclosed using standard email protocols beyond the
     ability to probe, via send-and-fail, the existance of a reachable
     account associated with a telephone number, and via the NDN, determine
     in which domain the account resides.
     However, the use of ENUM records to create routeable email addresses
     from telephone numbers provides bulk-emailers the capablities to send
     email to a large set of recipients where only the telephone number is
     known or where telephone numbers are guessed.
  6. References
  [E164] CCITT Recommendation E.164 (1991), Telephone Network and ISDN
      Operation, Numbering, Routing and Mobile Service - Numbering Plan for
      the ISDN Era.
  [ENUM] P. Faltstrom, M. Mealling, "The E.164 to URI DDDS Application
  [NAPTR] M. Mealling and R.D. Daniel, "The Naming Authority Pointer
      (NAPTR) DNS Resource Record", RFC 2915, September 2000.
  [VPIM2] Vaudreuil, Greg, Parsons, Glen, "Voice Profile for Internet
      Mail, Version 2", Work-in-Progress, Feb 2002.
  [VPIMDIR] A. Brown and G. Vaudreuil "VPIM Directory Schema", work-in-
      progress, <draft-ietf-vpim-vpimdir-04.txt>, February 2003.
  7. Copyright Notice
     "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.
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     This document and the information contained herein is provided on an
  8. Authors' Addresses
     Gregory M. Vaudreuil
     Lucent Technologies,
     7291 Williamson Rd
     Dallas, Tx 75214
     Phone/Fax: +1-214 823 9325
     Email: GregV@ieee.org
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