ENUM Working Group R. Brandner Internet Draft Siemens L. Conroy Siemens R. Stastny OeFEG Expires: August 2003 February 2003 Registration for enumservices voice and video Status of this Memo This document is an Internet-Draft and is in full conformance with all provisions of Section 10 of RFC2026 [1]. 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 This document registers a group of 'enumservices' [2] to be used to indicate that the associated resources are capable of interactive media stream exchange. Specifically, the "enumservices" registered with this document are 'voice' and 'video' using the URI schemes 'sip:', 'h323:' and 'tel:'. Table of Contents TBD 1. Introduction ENUM (E.164 Number Mapping, RFC2916bis [2]) is a system that transforms E.164 numbers [3] into domain names and then uses DNS (Domain Name Service, RFC1034 [4]) services like delegation through NS records and NAPTR records to look up what services are available for a specific domain name. This document registers 'enumservices' according to the guidelines given in RFC2916bis to be used for provisioning in the services field of a NAPTR[6] resource record to indicate what class of functionality a given end point offers. The registration is defined within the DDDS (Dynamic Delegation Discovery System [5][6][7][8][9]) hierarchy, for use with the "E2U" DDDS Application defined in RFC2916bis The following 'enumservices' are registered with this document: 'voice' and 'video'. These share a common feature in that they each indicate that the functionality of the given end points and the associated resources are capable of exchanging interactive media streams. According to RFC2619bis, the 'enumservice' registered must be able to function as a selection mechanism when choosing one NAPTR resource record from another. That means that the registration MUST specify what is expected when using that very NAPTR record, and the URI scheme which is the outcome of the use of it. Therefore an 'enumservice' acts as a hint, indicating the kind of service with which the URI constructed using the regexp field is associated. There can be more than one 'enumservice' included within a single NAPTR; this indicates that there is more than one service that can be achieved using the associated URI scheme. The common thread with this set of definitions is that they reflect the kind of service that the end user will hope to achieve with the communication using the associated URI. The services specified here are intended NOT to specify the protocol or even method of connection that MUST be used to achieve each service. Instead they define the kind of interactive behavior that an end user will expect, leaving the end system to decide (based on policies outside the remit of this specification) how to execute the service. Since the same URI scheme may be used for different services (e.g. 'tel:'), and the same kind of service may use different URI schemes (e.g. for VoIP 'sip:', 'h323:' and 'tel:' may be used), it is necessary in some cases to specify the service and the URI scheme used. The service parameters defined in RFC2916bis allow therefore a 'type' and a 'subtype' to be specified. Within this set of specifications the convention is assumed that the 'type' (being the more generic term) is defining the service and the 'subtype' is defining the URI scheme. 2. Abbreviations TBD 3. Voice Service 3.1 Introduction The enumservices registered in this section indicate that the resource identified by the associated URI is capable of being contacted to provide a communication session during which interactive media streams carrying voice data can be exchanged. 3.2 Voice Service Registration with 'tel:' Enumservice Name: "voice" Type: "voice" Subtype: "tel" URI Scheme: 'tel:' Functional Specification: This enumservice indicates that the resource identified by the associated URI scheme is capable of being called using a PSTN by dialing the number of the URI in order to set up the voice communication. If a dialing device is not present, a SIP or H.323 Client can be invoked and, by using the tel: URI, set up a session for voice communication. Although SIP and H.323 has its own negotiation method within the protocol, so that the client MAY be offered another kind of communication session after negotiation, this SHOULD NOT happen with this combination. The querying user is expecting a voice communication. Security Considerations: There are no specific security issues with this 'enumservice'. However, the general considerations of section 6 apply. Intended Usage: COMMON Author: Rudolf Brandner, Lawrence Conroy, Richard Stastny (for author contact detail see section 8) Any other information the author deems interesting: None 3.3 Voice Service Registration with 'sip:' Enumservice Name: "voice" Type: "voice" Subtype: "sip" URI Scheme: 'sip:' Functional Specification: This enumservice indicates that the resource identified by the associated URI scheme is capable of engaging in a voice communication using SIP [12]. Note that SIP has its own negotiation method within the protocol, so that the client MAY be offered another kind of communication session after negotiation. However, this combination gives more information to the querying user than would be the case for the "sip" enumservice [13]. The implication of this combination is that, if selected, the querying user can engage in an interactive voice communication; thus the registrant SHOULD include such an entry only for those cases where this is possible. Security Considerations: There are no specific security issues with this 'enumservice'. However, the general considerations of section 6 apply. Intended Usage: COMMON Author: Rudolf Brandner, Lawrence Conroy, Richard Stastny (for author contact detail see section 8) Any other information the author deems interesting: None 3.4 Voice Service Registration with 'h323:' Enumservice Name: "voice" Type: "voice" Subtype: "h323" URI Scheme: 'h323:' Functional Specification: This enumservice indicates that the resource identified by the associated URI scheme is capable of engaging in a voice communication using H.323 [14]. Note that H.323 has its own negotiation method within the protocol set, so that the client MAY be offered another kind of communication session after negotiation. However, this combination gives more information to the querying user than would be the case for the "h323" enumservice [15]. The implication of this combination is that, if selected, the querying user can engage in an interactive voice communication; thus the registrant SHOULD include such an entry only for those cases where this is possible. Security Considerations: There are no specific security issues with this 'enumservice'. However, the general considerations of section 6 apply. Intended Usage: COMMON Author: Rudolf Brandner, Lawrence Conroy, Richard Stastny (for author contact detail see section 8) Any other information the author deems interesting: None 4. Video Service 4.1 Introduction The enumservices registered in this section indicate that the resource identified by the associated URI is capable of being contacted to provide a communication session during which interactive media streams carrying audio and video data can be exchanged. 4.2 Video Service Registration with 'tel:' Enumservice Name: "video" Type: "video" Subtype: "tel" URI Scheme: 'tel:' Functional Specification: This enumservice indicates that the resource identified by the associated URI scheme is capable of being called using the PSTN by dialing the number of the URI in order to set up a audio/video communication. If a dialing device is not present, a SIP Client can be invoked and, by using the tel: URI, set up a session for audio/video communication. Although SIP and H.323 has its own negotiation method within the protocol, so that the client MAY be offered another kind of communication session after negotiation, this SHOULD NOT happen with this combination. The querying user is expecting an audio/video communication. Security Considerations: There are no specific security issues with this 'enumservice'. However, the general considerations of section 6 apply. Intended Usage: COMMON Author: Rudolf Brandner, Lawrence Conroy, Richard Stastny (for author contact detail see section 8) Any other information the author deems interesting: None 4.3 Video Service Registration with 'sip:' Enumservice Name: "video" Type: "video" Subtype: "sip" URI Scheme: 'sip:' Functional Specification: This enumservice indicates that the resource identified by the associated URI scheme is capable of engaging in an audio/video communication using SIP [12]. Note that SIP has its own negotiation method within the protocol, so that the client MAY be offered another kind of communication session after negotiation. However, this combination gives more information to the querying user than would be the case for the "sip" enumservice [13]. The implication of this combination is that, if selected, the querying user can engage in an interactive audio/video communication; thus the registrant SHOULD include such an entry only for those cases where this is possible. Security Considerations: There are no specific security issues with this 'enumservice'. However, the general considerations of section 6 apply. Intended Usage: COMMON Author: Rudolf Brandner, Lawrence Conroy, Richard Stastny (for author contact detail see section 8) Any other information the author deems interesting: None 4.4 Video Service Registration with 'h323:' Enumservice Name: "video" Type: "video" Subtype: "h323" URI Scheme: 'h323:' Functional Specification: This enumservice indicates that the resource identified by the associated URI scheme is capable of engaging in an audio/video communication using H.323 [14]. Note that H.323 has its own negotiation method within the protocol set, so that the client MAY be offered another kind of communication session after negotiation. However, this combination gives more information to the querying user than would be the case for the "h323" enumservice [15]. The implication of this combination is that, if selected, the querying user can engage in an interactive call that can include video communication; thus the registrant SHOULD include such an entry only for those cases where this is possible. Security Considerations: There are no specific security issues with this 'enumservice'. However, the general considerations of section 6 apply. Intended Usage: COMMON Author: Rudolf Brandner, Lawrence Conroy, Richard Stastny (for author contact detail see section 8) Any other information the author deems interesting: None 5. Additional Information Editor note: Is there any necessary additional information? TBD 6. Security Considerations DNS, as used by ENUM, is a global, distributed database. Thus any information stored there is visible to anyone anonymously. Whilst this is not qualitatively different from publication in a Telephone Directory, it does open the data subject to having "their" information collected automatically without any indication that this has been done or by whom. Such data harvesting by third parties is often used to generate lists of targets for unrequested information; in short, they are used to address "spam". Anyone who uses a Web-archived mailing list is aware that the volume of "spam" email they are sent increases when they post to the mailing list; publication of a telephone number in ENUM is no different, and may be used to send "junk faxes" or "junk SMS" for example. Many mailing list users have more than one email address and use "sacrificial" email accounts when posting to such lists to help filter out unrequested emails sent to them. This is not so easy with published telephone numbers; the PSTN E.164 number assignment process is much more involved and usually a single E.164 number (or a fixed range of numbers) is associated with each PSTN access. Thus providing a "sacrificial" phone number in any publication is not possible. Due to the implications of publishing data on a globally accessible database, as a principle the data subject MUST give their explicit informed consent to data being published in ENUM. In addition, they should be made aware that, due to storage of such data during harvesting by third parties, removal of the data from publication will not remove any copies that have been taken; in effect, any publication may be permanent. However, regulations in many regions will require that the data subject can at any time request that the data is removed from publication, and that their consent for its publication is explicitly confirmed at regular intervals. When placing a voice or video call via the PSTN or sending a message via the Public Land Mobile Network, the sender may be charged for this action. In both kinds of network, calling or messaging to some numbers is more expensive than sending to others; both networks have "premium rate" services that can charge considerably more than a "normal" call or message destination. As such, it is important that the end user be asked to confirm sending the message, and that the destination number be presented to them. It is the originating user's choice on whether or not to place a call to this destination number, but they SHOULD be shown the destination number so that they can make this decision Where voice or video terminals are configured to accept incoming calls, there SHOULD be an indication presented to the user that an incoming call is being offered. Particularly with some video systems, the terminal may be configured to "auto-accept" the call. In this case there MUST be an obvious indication presented to the calling user that this has been done. Systems configured to auto-accept audio/video calls that are sent to a number published in a global public directory may be used by unexpected individuals to check for the presence or otherwise of people for with a view to stealing property or other unwelcome acts. Whilst "security through obscurity" may have seemed acceptable when the access address was known to only a few, publication within ENUM removes the obscurity, so leaving (for example) a "WebCam" switched on after such publication is even less wise than in other situations. In addition to the specific security considerations given above, all security considerations given in RFC2916bis apply. 7. References 1 Scott Bradner, RFC2026, "The Internet Standards Process - Revision 3", October 1996. 2 P. Faltstrom, M. Mealling, "The E.164 to URI DDDS Application (ENUM)", draft-ietf-enum-rfc2916bis-03.txt, Work in progress, January 2003 3 ITU-T, "The International Public Telecommunication Number Plan", Recommendation E.164, May 1997 4 P. Mockapetris, RFC1034, "DOMAIN NAMES - CONCEPTS AND FACILITIES", November 1987 5 M. Mealling, RFC 3401, "Dynamic Delegation Discovery System (DDDS) Part One: The Comprehensive DDDS", October 2002 6 M. Mealling, RFC 3402, "Dynamic Delegation Discovery System (DDDS) Part Two: The Algorithm", October 2002 7 M. Mealling, RFC 3403, "Dynamic Delegation Discovery System (DDDS) Part Three: The Domain Name System (DNS) Database", October 2002 8 M. Mealling, RFC 3404, "Dynamic Delegation Discovery System (DDDS) Part Four: The Uniform Resource Identifiers (URI)", October 2002 9 M. Mealling, RFC 3405, "Dynamic Delegation Discovery System (DDDS) Part Five: URI.ARPA Assignment Procedures", October 2002 10 H. Schulzrinne, A. Vaha-Sipila, "URIs for Telephone Calls", draft-antti-RFC2806bis-08.txt, Work in progress, February 2003 11 ETSI TS 102 172, "Minimum Requirements for Interoperability of European ENUM Trials", February 2003 12 J. Rosenberg, H. Schulzrinne, G. Camarillo, A. Johnston, J. Peterson, R. Sparks, M. Handley, E. Schooler, RFC 3261, "SIP: Session Initiation Protocol", June 2002 13 J. Peterson, "enumservice registration for SIP Addresses-of-Record", draft-peterson-enum-sip-00.txt, Work in progress, September 2002 14 ITU-T Recommendation H.323, "Packet-based multimedia communications systems", Nov 2000 15 O. Levin, "ENUM Service Registration for H.323 URL", draft-ietf-enum-h323-00.txt, Work in progress, February 2003 8. Author's Addresses Rudolf Brandner Siemens ICN Hofmannstrasse 51 Munich Germany email: voice: web: Lawrence Conroy Siemens Roke Manor Research Roke Manor Romsey U.K. email: voice: Richard Stastny OeFEG Postbox 147 1103 Vienna Austria email: voice: 9. 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