ENUM domain

Your phone number becomes your digital address.

Your phone number can do more than you think. Turn it into the universal key for all your digital services.

What is an ENUM domain?

ENUM stands for “Telephone Number Mapping.” It is essentially a bridge between the world of telecommunications and the Internet. With a single ENUM domain, you can combine all your contact options under your familiar phone number:

Landline and mobile phone connections

Private and business email addresses

Fax machines

Video conferencing addresses

The system automatically recognizes what you want to do and selects the right channel. When you write an email, the appropriate email address is used. When you make a call, the right phone rings.

How does the technology behind it work?

ENUM uses the proven Domain Name System (DNS) – the Internet's address book. Your telephone number is converted into a special domain.

Interaktive Animation
Example: The ENUM domain is assigned to the telephone number:

To do this, simply write down the digits of the phone number in reverse order and add the special extension .e164.arpa . This extension has been reserved specifically for this purpose on the Internet.

How to register your ENUM domain

Select a provider

Contact a provider that offers ENUM domains to register your domain. You can also obtain the necessary name service from a DENIC member, commission another provider, or operate it yourself.

Check availability

Only domains based on the following German telephone numbers can be registered:

  • Geographic telephone numbers (all German area codes)
  • Mobile phone numbers with the prefixes (0)15, (0)16, and (0)17
  • National subscriber numbers ((0)32)
  • National freephone numbers ((0)800)
  • Personal telephone numbers ((0)700)
  • Service numbers ((0)18)

Observe regulations

Before placing your order, please familiarize yourself with the following documents. A domain contract with DENIC will only be concluded if all provisions are met:

Your German ENUM domain: Securely managed by DENIC

Since 2006, DENIC has been responsible for registering ENUM domains for the German numbering space (+49).

What makes ENUM domains special is that there are no name conflicts, unlike with other domains. This is because an ENUM domain can only be registered by the person or company that owns the corresponding telephone number. This creates clarity and security.

At DENIC, we ensure compliance with this rule through our ENUM domain conditions and ENUM domain guidelines, as well as a complaint process.
 

For a deeper insight into the technical fundamentals of ENUM, the following detailed information is available:

  • Protocol and standardization

    The ENUM protocol was developed by the ENUM Working Group of the IETF (Internet Engineering Task Force) and documented in Internet standard RFC3761. In this environment, there are a number of other Internet standards for future RFCs.

  • Integration into the Domain Name System (DNS)

    The ENUM service accesses the existing Domain Name System (DNS) of the Internet via a subdomain reserved for ENUM. The IAB (Internet Architecture Board) proposed .e164.arpa for this purpose, because E.164 is the standard in which the ITU (International Telecommunications Union) describes the international numbering plan for telecommunications, and .arpa is a special top-level domain used as an “address and routing parameter area” for infrastructure services.

  • Structure of an ENUM domain

    An ENUM domain is formed by placing the digits of the telephone number in reverse order, separated by dots, in front of the suffix .e164.arpa. For example, DENIC's telephone number +49 69 27 2350 is linked to the domain 0.5.3.2.7.2.9.6.9.4.e164.arpa.

  • Administration and delegation

    RIPE NCC in Amsterdam acts as the international registry for .e164.arpa. The German part of the ENUM name tree (i.e., .9.4.e164.arpa) was delegated to DENIC eG in consultation with the relevant committees. The levels below this can then be managed by the customer's provider or by the customer themselves.

Sending a fax or forwarding calls via an IP network is made possible by an ENUM query. The following graphic illustrates this process, which runs automatically in the background.

How ENUM domain queries work

  1. Start: The sender enters the destination fax number on the device.
  2. DNS query: The device converts the number into an ENUM domain (e.g., 4.3.2.1.9.4.e164.arpa) and sends a query (DNS query) to the ENUM server.
  3. DNS response: The server responds with the digital destination address, e.g., an email-like address such as ifax: fax@denic.de.
  4. Connection: This information is used to establish a direct fax-over-IP connection to the recipient and transmit the fax.

Technical details

Technically, an ENUM client accesses ENUM name servers with so-called Naming Authority Pointer (NAPTR) records for this query via the .e164.arpa name server.

These records define which communication services (e.g., fax, email, VoIP) are available for the requested phone number. The result is a list of addresses, known as Uniform Resource Identifiers (URI), which are used in a specified order to address the desired service and establish the connection.

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