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ENUM
ENUM

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What is ENUM? 

ENUM is a protocol that is the result of work of the Internet Engineering Task Force's (IETF's) Telephone Number Mapping Working Group. The charter of this working group was to define a Domain Name System (DNS)-based architecture and protocols for mapping a telephone number to a Uniform Resource Identifier (URI) which can be used to contact a resource associated with that number. The protocol itself is defined in RFC 3761: The E.164 to URI DDDS Application (ENUM) which obsoletes RFC 2916.

The protocol provides facilities to resolve E.164 telephone numbers into other resources or services on the internet. ITU-T Recommendation E.164 is the international public telecommunication telephone numbering plan and current ENUM delegations can be found here. The syntax of Uniform Resource Identifiers (URIs) is defined in RFC 2396 (1998). ENUM makes extensive use of Naming Authority Pointer records defined in RFC 2915 in order to identify available ways or services for contacting a specific node identified through the E.164 number. Another important related RFC is RFC 2168: Resolution of Uniform Resource Identifiers using the Domain Name System.

Other related Internet drafts and RFCs can be found here. Wikipedia's discussion of ENUM can be found here.

The Internet Architecture Board (IAB) and ITU-T Study Group 2 are discussing collaboration on the operational, administration and delegation issues related to deployment of ENUM protocol-based services. This requires extensive consultation with administrators of resources derived from the international E.164 numbering plan including national and integrated numbering plan administrators.
 

Other Links
Telephone Number Mapping Working Group
ENUM Wikipedia Entry
Ray Fassett's Global ENUM
RIPE NCC ENUM Pages
United States ENUM Forum
Washington Internet Project Pages on ENUM
Events
8 February 2002: ITU Tutorial Workshop on ENUM.

17 January 2001: ITU ENUM Workshop on administrative issues related to deployment of the ENUM protocol. See Description and Objective of the Workshop, Agenda and Registration Form (also in Word).

19-26 October 2000: ITU-T Study Group 2, Working Party 1/2: Meeting of Working Party 1/2 (Numbering,Routing, Global Mobility and Service Definition), Berlin, Germany, Delayed Contributions

25-27 January 2000: IP-Telecoms Interworking Workshop on Naming, Numbering, Addressing and Routing (NNAR)
 

Resources
October 1 2001: Presentation by Mr. Jeffrey Ganek, Neustar, at the Telecom Policy Summit 2001, on E Pluribus ENUM!
September 1 2001: ETNO Reflection Document on the ETSI draft TR 5TD197c about ENUM
August 21 2001: Presentation by Mr. Kevin McCandless on Understanding ENUM and Current Status (Power Point)
June 5 2001: Presentation by Mr. Robert Shaw, ITU at the DTI ENUM Workshop on Global ENUM Implementation (Power Point).
June 1-2 2001: Presentation by Mr. Robert Shaw, ITU at the ICANN Governmental Advisory Committee on ENUM Implementation (Power Point).
 March 28-29 2001: US SGA Ad-Hoc Meeting on ENUM: 

February 12-13 2001: US SGA-Workshop on ENUM: 

January 17 2001: ITU ENUM Workshop:

News

News from the ITU SPU Newslog on ENUM  
[CaRP] XML error: syntax error at line 1

ITU Resources

Current ENUM Delegations

Information on ENUM Trials

Interim procedures for Geographic Country Codes

Interim procedures for shared Country Codes for Networks and Groups of Countries

FAQ

1. What is ENUM?
2. What is ITU-T E.164? Are there related standards?

3. What is the related domain name system (DNS) zone under which a parallel E.164 name space will be administered?
4. How is the related DNS zone constructed?
5. What is the operational, administration and delegation model?

See also DDDS Frequently Asked Questions

1. What is ENUM?

ENUM is a protocol that is the result of work of the Internet Engineering Task Force's (IETF's) Telephone Number Mapping working group. The charter of this working group was to define a Domain Name System (DNS)-based architecture and protocols for mapping a telephone number to a Uniform Resource Identifier (URI) which can be used to contact a resource associated with that number. The protocol itself is defined in RFC 3761: The E.164 to URI DDDS Application (ENUM) which obsoletes RFC 2916. The protocol provides facilities to resolve E.164 telephone numbers into other resources or services on the internet. ITU-T Recommendation E.164 is the international public telecommunication telephone numbering plan and current ENUM delegations can be found here. The syntax of Uniform Resource Identifiers (URIs) is defined in RFC 2396 (1998). ENUM makes extensive use of Naming Authority Pointer records defined in RFC 2915 in order to identify available ways or services for contacting a specific node identified through the E.164 number. Other related Internet drafts and RFCs can be found here.

2. What is ITU-T E.164? Are there related standards?

Recommendation E.164 describes the international public telecommunication numbering plan. Recommendation E.190 describes the general principles to be utilized in the assignment of ITU-T E-Series international numbering resources. Recommendation E.164.1 describes the procedures and criteria for the reservation, assignment, and reclamation of E.164 country codes and associated Identification Code (IC) assignments. The criteria and procedures are provided as a basis for the effective and efficient utilization of the available E.164 numbering resources. 

3. What is the related domain name system (DNS) zone under which a parallel E.164 name space will be administered?

The Internet Architecture Board has recommended the use of the e164.arpa zone. The IAB has issued a related statement Infrastructure Domain and Subdomains. ITU Member States are currently discussing the responsibility, delegation and authority for the ENUM "root zone". While discussions have been initiated on this topic at the recent ITU-T SG2 meeting in January/February 2001, they have yet to be concluded and the international resolution of these concerns could have an eventual impact on the IAB selection of e164.arpa.

4. How is the related DNS zone constructed?

For example, lets construct the related DNS zone to look up resources associated with the information desk of the Louvre Museum in Paris, France, which can be found at the telephone number +33 1 40 20 51 51.

Write the E.164 number is written in its full form, including the countrycode. 

Example: +33 1 40 20 51 51

Remove all non-digit characters with the exception of the leading '+'. 

Example: +33140205151

Remove all characters with the exception of the digits. 

Example: 33140205151

Put dots (".") between each digit. 

Example: 3.3.1.4.0.2.0.5.1.5.1

Reverse the order of the digits. 

Example: 1.5.1.5.0.2.0.4.1.3.3 

Considering the recommendation of the Internet Architecture Board, append the string ".e164.arpa" to the end. 

Example: 1.5.1.5.0.2.0.4.1.3.3.e164.arpa

5. What is the operational, administration and delegation model?

The Internet Architecture Board (IAB) and ITU-T Study Group 2 are discussing collaboration on the operational, administration and delegation issues related to deployment of ENUM protocol-based services. This requires extensive consultation with administrators of resources derived from the international E.164 numbering plan including national and integrated numbering plan administrators. The ITU-T has defined Interim procedures for Geographic Country Codes and Interim procedures for shared Country Codes for Networks and Groups of Countries.

 

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Updated : 2011-04-04