Voice Message Routing Service
RFC 4238

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Network Working Group                                       G. Vaudreuil
Request for Comments: 4238                           Lucent Technologies
Category: Standards Track                                   October 2005

                     Voice Message Routing Service

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 (2005).

Abstract

   Voice messaging is traditionally addressed using telephone number
   addressing.  This document describes two techniques for routing voice
   messages based on a telephone number.  The complete service uses the
   Voice Profile for Internet Mail (VPIM) Directory service to lookup a
   VPIM email address with a telephone number and confirm that the
   address is both valid and associated with the intended recipient.
   However, this service will take time to become widely deployed in the
   near term.  This document also describes a basic send-and-pray
   service that routes and delivers messages using only the ENUM
   telephone number resolution service and the existing DNS mail routing
   facilities.

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RFC 4238             Voice Message Routing Service          October 2005

Table of Contents

   1. Design Goals ....................................................2
   2. The Complete Service ............................................3
      2.1. Specification of Service "E2U+VPIM:LDAP" ...................3
      2.2. VPIM Directory Discovery ...................................4
      2.3. Address Query ..............................................4
   3. The Basic Service ...............................................4
      3.1. Specification of Service "E2U+VPIM:Mailto:" ................5
      3.2. Address Construction .......................................6
      3.3. Interdomain Message Routing ................................6
      3.4. Intradomain Message Routing ................................6
           3.4.1. Directory-Enabled Routing ...........................6
           3.4.2. Service-based Mail Routing ..........................7
   4. Security Considerations .........................................7
      4.1. Unsolicited Bulk Email .....................................7
      4.2. DNS-based Attacks ..........................................7
   5. IANA Considerations .............................................8
   6. References ......................................................8
      6.1. Normative References .......................................8
      6.2. Informative References .....................................8

1.  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 retrieve the
   VPIM-specific email address that will be used 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 available.  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.  At a minimum, it
   should be possible to establish a simple mail forwarding rule that

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RFC 4238             Voice Message Routing Service          October 2005

   sends 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.  95% of the time, that constraint can be a two-