Internet Draft Greg Vaudreuil Expires in six months Lucent Technologies February 03, 2005 Voice Message Routing Service Status of this Memo 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 a "work in progress". The list of current Internet-Drafts can be accessed at http://www.ietf.org/1id-abstracts.html The list of Internet-Draft Shadow Directories can be accessed at http://www.ietf.org/shadow.html Intellectual Property Notice By submitting this Internet-Draft, I certify that any applicable patent or other IPR claims of which I am aware have been disclosed, or will be disclosed, and any of which I become aware will be disclosed, in accordance with RFC 3668. Copyright Notice Copyright (C) The Internet Society (2005). All Rights Reserved. Overview 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 Internet Draft VPIM Routing February 03, 2005 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. NORMATIVE REFERENCES..............................................9 7. INTELLECTUAL PROPERTY NOTICE.....................................10 8. COPYRIGHT NOTICE.................................................10 9. AUTHORS' ADDRESSES...............................................10 Vaudreuil Expires 7/03/05 [Page 2] Internet Draft VPIM Routing February 03, 2005 1. Abstract This document describes two mechanisms by which a sending VPIM system may determine the destination mailbox given a telephone number. Both mechanisms build upon ENUM. One mechanism utilizes an LDAP query to determine recipient capabilities and retrieve address confirmation information such as a spoken or text name. 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 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. 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. Vaudreuil Expires 7/03/05 [Page 3] Internet Draft VPIM Routing February 03, 2005 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:" * Type: Voice * Subtype: DIR * 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 resource. 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. Vaudreuil Expires 7/03/05 [Page 4] Internet Draft VPIM Routing February 03, 2005 Example: Query: 2.1.2.1.5.5.5.3.1.6.1.e164.arpa Responses: IN NAPTR 10 10 "U" "E2U+voice:DIR" \ "!^.*$!ldap://vdir1.Zcorp.com/telephoneNumber=\1!" . IN NAPTR 10 20 "U" " E2U+Voice:DIR" \ "!^.*$!ldap://vdir2.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-1, NAPTR-2, NAPTR-3, NAPTR-4] 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] Vaudreuil Expires 7/03/05 [Page 5] Internet Draft VPIM Routing February 03, 2005 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:" * Type: VPIM * Subtype: MAILTO * 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. Vaudreuil Expires 7/03/05 [Page 6] Internet Draft VPIM Routing February 03, 2005 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 resource. 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 known. 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. Vaudreuil Expires 7/03/05 [Page 7] Internet Draft VPIM Routing February 03, 2005 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 Vaudreuil Expires 7/03/05 [Page 8] Internet Draft VPIM Routing February 03, 2005 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. IANA Considerations This specification registers the E2U+VPIM and E2U+Voice services according to the specifications and guidelines in RFC 3761 [ENUM] and the definitions in this document. 7. Normative References [E164] CCITT Recommendation E.164 (1991), Telephone Network and ISDN Operation, Numbering, Routing and Mobile Service - Numbering Plan for the ISDN Era. [ENUM] Falstrom, P., M. Mealling, "The E.164 to Uniform Resource Identifiers (URI) Dynamic Delegation Discovery System (DDDS) Application (ENUM)", RFC3761, April 2004 RFC 3761 [NAPTR-1] Mealling, M., "Dynamic Delegation Discovery System (DDDS) Part One: The Comprehensive DDDS", RFC 3401, October 2002. [NAPTR-2] Mealling, M., "Dynamic Delegation Discovery System (DDDS) Part Two: The Algorithm", RFC 3402, October 2002. [NAPTR-3] Mealling, M., "Dynamic Delegation Discovery System (DDDS) Part Three: The Domain Name System (DNS) Database", RFC 3403, October 2002. [NAPTR-4] Mealling, M., "Dynamic Delegation Discovery System (DDDS) Part Four: The Uniform Resource Identifiers (URI) Resolution Application", RFC 3404, October 2002. [VPIMV2] Vaudreuil, Greg, Parsons, Glen, "Voice Profile for Internet Mail, Version 2", RFC 3801, June 2004. [VPIMDIR] G. Vaudreuil "VPIM Directory Schema", work-in-progress, , October 12, 2004. Vaudreuil Expires 7/03/05 [Page 9] Internet Draft VPIM Routing February 03, 2005 8. Intellectual Property Notice The IETF takes no position regarding the validity or scope of any intellectual property or other rights that might be claimed to pertain to the implementation or use of the technology described in this document or the extent to which any license under such rights might or might not be available; neither does it represent that it has made any effort to identify any such rights. Information on the IETF's procedures with respect to rights in standards-track and standards-related documentation can be found in BCP-11. Copies of claims of rights made available for publication and any assurances of licenses to be made available, or the result of an attempt made to obtain a general license or permission for the use of such proprietary rights by implementors or users of this specification can be obtained from the IETF Secretariat. The IETF invites any interested party to bring to its attention any copyrights, patents or patent applications, or other proprietary rights which may cover technology that may be required to practice this standard. Please address the information to the IETF Executive Director. 9. Copyright Notice Copyright (C) The Internet Society (2005). This document is subject 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. 10. Authors' Addresses Gregory M. Vaudreuil Lucent Technologies 9489 Bartgis Ct Frederick, MD 21702 Email: GregV@ieee.org Vaudreuil Expires 7/03/05 [Page 10]