Internet Draft Greg Vaudreuil Expires in six months Lucent Technologies July 13, 2000 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 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/ietf/1id-abstracts.txt The list of Internet-Draft Shadow Directories can be accessed at http://www.ietf.org/shadow.html. To learn the current status of any Internet-Draft, please check the "1id-abstracts.txt" listing contained in the Internet-Drafts Shadow Directories on ftp.is.co.za (Africa), nic.nordu.net (Europe), munnari.oz.au (Pacific Rim), ds.internic.net (US East Coast), or ftp.isi.edu (US West Coast). Copyright Notice Copyright (C) The Internet Society (2000). All Rights Reserved. This Internet-Draft is in conformance with Section 10 of RFC2026. 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 mechanism to map between a telephone number and a VPIM email address and confirm that the address is both valid and the assocaited 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 message using only the existing DNS mail routing facilies, the ENUM telephone number resolution service, and a set of pre-defined address creation rules. Please send comments on this document to the VPIM working group mailing list Internet Draft VPIM Routing July 13, 2000 Working Group Summary This is a submission to the IETF VPIM working group. Vaudreuil Expires 1/1/01 [Page 2] Internet Draft VPIM Routing July 13, 2000 Table of Contents 1. ABSTRACT ..........................................................4 2. DESIGN GOALS ......................................................4 3. THE COMPLETE SERVICE ..............................................5 3.1 VPIM Directory Discovery ........................................5 3.2 Address Query ...................................................5 4. THE BASIC SERVICE .................................................6 4.1 Address Construction ............................................6 4.2 Inter-domain Message Routing ....................................7 4.3 Intra-domain Message Routing ....................................7 5. SECURITY CONSIDERATIONS ...........................................9 6. REFERENCES ........................................................9 7. ACKNOWLEDGMENTS ..................................................10 8. COPYRIGHT NOTICE .................................................10 9. AUTHORS' ADDRESSES ...............................................10 Vaudreuil Expires 1/1/01 [Page 3] Internet Draft VPIM Routing July 13, 2000 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 the ENUM address resolution service to determine the VPIM directory, and then use LDAP to retreive the VPIM email address to use for message routing. The most basic send-and-pray message service uses only address construction rules, 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 it's internal destination. It should be possible at a minimum to establish a simple mail forwarding rule to send all inbound VPIM message 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 ocure 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 1/1/01 [Page 4] Internet Draft VPIM Routing July 13, 2000 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, and then query that server for the email address and any additional attributed desired. 3.1 VPIM Directory Discovery The VPIM directory server is found by querying DNS for the SRV record associated with the domain name of the recipient as found in the address resolution step. The DNS query name is created by appending the VPIM service request "_VPIMDIR._TCP" to the reverse-dotted telephone number based domain name as described by [ENUM]. The telephone number used for the directory location SHOULD NOT contain sub-address information. See [ENUM] Note: There are potential interactions and an increase in provisioning burden when using a domain name with more levels than necessary, especially when using CNAME redirection services. In the absence of better understanding, this is best avoided. See [ENUMOPS] Example: Query: _VPIM._TCP.2.1.2.1.5.5.5.3.1.6.1.e164.arpa Response: SRV=vpimdir1.example.com weight=10 preference=10 port=389 SRV=vpimdir2.example.com weight=20 preference=10 port=389 Given the lack of elegant client-side redundancy for LDAP, and the real-time requirements for a response, the VPIMDIR service should be provided on a high-availability server to ensure the service is available on the first try. 3.2 Address Query Once the VPIM directory is discovered, the client should issue a LDAP query for the vPIMrFC822Address. That is the address that should be used as the value for both the RFC822 to: field and the SMTP RCPT TO command. See [VPIMDIR] To facilitate higher system availability, it is recommended that VPIMDIR servers be deployed in redundant sets. These servers should be listed in the SRV records with various weightings. The querying system should attempt a connection to the lowest weight VPIMDIR server. If it is down, the second should be contacted. Vaudreuil Expires 1/1/01 [Page 5] Internet Draft VPIM Routing July 13, 2000 4. The Basic Service The basic service relies upon address creation rules to mechanically construct an address that may be routed by the existing infrastructure to the recipient's domain. In the recipient's domain, the machanically constructed address may be further routed using intra- domain mail routing techniques such as those defined in [LASER]. To facilitate a full range of intra-domain routing options, the constructed email address should contain both the recipients telephone number and an indication that the message is a VPIM message. For ease of processing in the recipients intra-domain 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 least- common denominator media and content types of the intended message *type*. 4.1 Address Construction Mechanically construct an email address using only an algorithm specific to the messaging service. For VPIM, the algorithm is as follows: 1) Normalize the telephone number into E.164 form. Presentation information such as spaces, prenthesis, periods, and dashes MUST be stripped. Sub-addresses if known and explicitly indicated should be appended to the address using the "+" sign. Construct the local part of the email address by prefixing a "+" sign to the E164 telephone number. Examples: +19727331212 (A Dallas, US based recipient) +441819031212+2 (A Wembly, UK based recipient) 2) Construct the domain name portion of the address from the telephone number. The sub-address does not affect the inter-domain routing of a message. Strip the sub-address portion of the telephone number, reverse and dot-stuff the digits consistent with the ENUM specification. Prefix the service selector "_VPIM" to the address and append the suffix "e164.arpa". Examples: _vpim.2.1.2.1.3.3.7.2.7.9.1.e164.arpa _vpim.2.1.2.1.3.0.9.1.8.1.4.4.e164.arpa 3) Concatentate the local part and the domain portion with the "@" symbol to yield the recipients basic VPIM address. Vaudreuil Expires 1/1/01 [Page 6] Internet Draft VPIM Routing July 13, 2000 Examples: +19727331212@_vpim.2.1.2.1.3.3.7.2.7.9.1.e164.arpa +441819031212+2@_vpim.2.1.2.1.3.0.9.18.1.4.4.e164.arpa This is the address that should be used as the value for both the RFC822 to: field and the SMTP RCPT TO command. 4.2 Inter-domain Message Routing The inter-domain routing of a constructed VPIM address is mechanically indistinguishable from existing email routing. No changes to the infrastructure ar required. The sending system consults the Domain name system for a MX record corresponding to the domain name and forwards the message to the indicated system. It is through the ENUM service that the MX records are provisioned for specific telephone number or whole blocks of delegated telephone numbers. Using the longest-match algorithms of DNS, the DNS routing system may be service-ignostic and does not need to have individual MX records for each service-specific sub-domain. However, if it is desired to send messages addressed with a given service to the mail server of a different domain, a service-specific MX record may be provisioned on a per-telephone number basis. See [ENUMOPS] for a more complete description of the structure of the ENUM service. 4.3 Intra-domain 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 intra-domain routing are an internal matter for the domain and do not affect the protocol. However, an understanding of common intra-domain routing techniques is essential to the mechanical creation of a useful address. 4.3.1 LASER Powered / Directory Enabled Routing Various proprietary directory mechanisms and the emerging LASER standard mechanism provide a means for a inbound mail router of the recipients 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 RCPT TO 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. 4.3.2 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 Vaudreuil Expires 1/1/01 [Page 7] Internet Draft VPIM Routing July 13, 2000 messaging server or a service-specific gateway into a larger telephone-number 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 domain name to re-route messages. In many cases, such as with SMS messaging to mobile phones, this server may external to the customers network. Vaudreuil Expires 1/1/01 [Page 8] Internet Draft VPIM Routing July 13, 2000 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 a simple algorithm 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. [VPIM2] Vaudreuil, Greg, Parsons, Glen, "Voice Profile for Internet Mail, Version 2", Work-in-Progress, July 2000. [VPIMDIR] A. Brown and G. Vaudreuil "VPIM Directory Schema", work-in- progress, July 2000. [ENUM] P. Faltstrom "E.164 number and DNS", Work-in-Progress, July 2000. [ENUMOPS] A. Brown and G. Vaudreuil "ENUM Service Specific Provisioning: Principles of Operation", Work-in-Progress, July 2000. Vaudreuil Expires 1/1/01 [Page 9] Internet Draft VPIM Routing July 13, 2000 7. Acknowledgments 8. Copyright Notice "Copyright (C) The Internet Society (2000). 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." 9. Authors' Addresses Gregory M. Vaudreuil Lucent Technologies, 17080 Dallas Parkway Dallas, TX 75248-1905 United States Phone/Fax: +1-972-733-2722 Email: GregV@ieee.org Vaudreuil Expires 1/1/01 [Page 10]