The H.323 specification  defines a means for building multimedia
communication services over an arbitrary Packet Based Network,
including the Internet. When H.323 is used in the context of the
Internet, it would be useful to take advantages of such services as
domain name system (DNS) and ENUM in order to help facilitate the
completion of multimedia calls.
This document registers an ENUM service for H.323 according to
specifications and guidelines in RFC 3761 .
2. ENUM Service Registration
As defined in , the following is a template covering information
needed for the registration of the enumservice specified in this
- Service Name: "E2U+H323"
- URI Scheme(s): "h323:"
- Functional Specification: see section "3. The E2U+H323 ENUM
- Security considerations: see section "5. Security Considerations"
- Intended usage: COMMON
- Author: Orit Levin
- Any other information that the author deems interesting: None
3. The E2U+H323 ENUM Service
This document defines the "E2U+H323" service to be used in the
"service" sub-field of the "enumservice" as defined in .
The H.323 related ENUM record MUST be populated with a standard H.323
URL as defined in . This URL MAY include parameters specifying
the specific protocols and the transport means the H.323 entity
The H.323 entity MUST fully comply with the procedures defined in 
for both record retrieval and processing by the DNS client.
If, as a result of the ENUM DNS lookup, an H.323 URL matching local
policies and capabilities is retrieved, the procedure defined in
section O.8.1 "Locating H.323 Destination" of  SHOULD be
4. Conventions used in this document
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in BCP 14, RFC 2119 .
5. Security Considerations
The h323-URL information, once populated in the DNS, effectively
becomes publicly accessible. The access to the H.323 destinations
(published using ENUM) can be secured by techniques and procedures
defined in H.235  - the security framework for H.323. The
framework defines means for achieving integrity, authentication,
non-repudiation, encryption, etc. for H.323 calls. An analysis of
threats specific to the dependence of ENUM on the DNS, and the
applicability of DNSSEC  to these, is provided in .
6. IANA Considerations
This document registers the E2U+H323 ENUM service according to
specifications and guidelines in RFC 3761  and the definitions in
7.1. Normative References
 Bradner, S., "Key words for use in RFCs to Indicate Requirement
Levels", BCP 14, RFC 2119, March 1997.
 "Packet-based multimedia communications systems", ITU-T
Recommendation H.323, 2003.
 Faltstrom, P. and M. Mealling, "The E.164 to Uniform Resource
Identifiers (URI) Dynamic Delegation Discovery System (DDDS)
Application (ENUM)", RFC 3761, April 2004.
 "Security and encryption for H-Series(H.323 and other H.245-
based) multimedia terminals", ITU-T Recommendation H.235, 2003.
 "Usage of URLs and DNS", ITU-T Recommendation H.323 Annex O,
7.2. Informative References
 R. Arends, et al., "Protocol Modifications for the DNS Security
Extensions", Work in Progress, February 2004.
9. Full Copyright Statement
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