ENUM makes internet-based communications services accessible using a single telephone number. Using ENUM, telephone numbers are converted to Internet addresses, allowing end users to link one or more communications services to their telephone number and providing a single point of contact for services such as Voice over IP (VoIP), email, presence and instant messaging.

The technical specification of ENUM is defined in the Internet Engineering Task Force standard, Request for Comments 6116 (RFC 6116).

ENUM uses the internet's domain name system (DNS) to map E.164 telephone numbers to uniform resource identifiers (URIs) - strings of characters that can identify resources such as documents, images, files, and e-mail and web addresses. ENUM enables the use of traditional E.164 telephone numbers in IP-based networks.

E.164 is the international telephone numbering plan written and administered by the ITU. The plan specifies the format, structure and administrative hierarchy of telephone numbers. At the root of the E.164 administrative hierarchy is the issuing of country codes by the ITU to member states, for example the country code for Australia is 61.

In the same way that E.164 provides the international numbering infrastructure - the domain, .arpa (standing for addressing and routing parameter area) is designated for internet infrastructure purposes. The two top-level domains of E.164 and .arpa are combined to create E.164.arpa, the host ENUM namespace. The ENUM specification provides an infrastructure support by mapping connections between an E.164 telephone number and a domain name server which will then enable numerous applications to be accessible via a telephone number. The DNS is the mechanism by which internet software translates names to IP addresses and vice versa.

ENUM is especially suited to VoIP applications and has the potential to assist in providing high-quality, end-to-end VoIP calls between different networks carried entirely over the internet.

ENUM on its own though is just a method of mapping telephone numbers to Internet addresses.  What it will be used for will largely be determined by the applications that are developed to use ENUM.

Australian ENUM Discussion Group

The former Australian Communications Authority (now ACMA) formed the Australian ENUM Discussion Group (AEDG) as a consultative and advisory body to assist in the development of a framework for ENUM in Australia.

The AEDG held its last meeting 15 July 2009. Future meetings can be convened as required.

Australian User ENUM trial

The trial of User ENUM was conducted from 6 June 2005 and to 6 June 2007. The Trial Evaluation can be viewed at the Australian ENUM trial website, operated by AusRegistry International.

Following the conclusion of the Australian ENUM trial, the Australian ENUM domain, .1.6.e164.arpa is no longer active

ENUM Trial Published Policies

Context Document for the Australian ENUM trial - Document drafted in conjunction with the Australian ENUM Discussion Group which outlines the framework and structure of the Australian ENUM trial for both policy and technical aspects

The Privacy Impact Assessment of the Australian ENUM trial - commissioned by the ACMA

Infrastructure ENUM

The Australian ENUM Discussion Group formed a working group in April 2007 to investigate and report on an alternate usage of ENUM known as infrastructure or carrier ENUM. Outputs from the working group are:

Further information

Last updated: 09 May 2017