What is ENUM?

ENUM is a technology platform enabling the transformation of phone numbers from E.164 standard into domain names in the Domain Name system (DNS). DNS enables translating domain names into IP addresses. Obtaining an IP address (e.g. of a server where a www server, servicing a domain name is held) for ENUM is not essential, in general it is about binding different telecommunication services with a phone number recorded as a domain name. ENUM uses NAPTR RR (The Naming Authority Pointer DNS Resource Record) in order to specify what services are bound with a particular domain name. Each NAPTR contains URI (Uniform Resource Identifier) description specifying the method of contact with the owner of a number. Therefore, a registrant may apply one universal number (identifier) while using a variety of telematics services.

In particular you may add/change the following services:

  • Mobile phone number,
  • Fixed phone number,
  • fax,
  • e-mail,
  • SIP address for VoIP,
  • voice mail,
  • instant messaging etc.

Besides adding new services it is also possible to assign to them different priorities, essential in using ENUM services, by telecommunication providers. NAPTR records enable to define methods of contact (e.g. forwarding a call to a mobile phone if a user is not available through VoIP or forwarding a call to a mobile phone when a user is not available at fixed phone number).

What is the form of a phone number in the ENUM domain?

So as a phone number can be inserted in DNS a modification of its structure must be effected. Let us assume that we want to convert a Polish phone number 22 380 83 00 into the ENUM domain:

  1. we add a country code to a phone number, in our case it is +48, resulting with +48 22 380 83 00
  2. we delete all signs accept digits, thus we obtain 48223808300
  3. we add dots between digits getting the following form:
  4. we reverse the order:
  5. we add a current Tier-0 zone, i.e. e164.arpa (arpa domain may be changed in future)
  6. finally we get the following form of the number:


NASK maintains a central database of ENUM domains within 8.4.e164.arpa zone. Registration is available through registrars.

If you want to become a registrar of ENUM domains within 8.4.e164.arpa zone, please contact us:

.pl Registrar Programme Development Team
e-mail: partner@dns.pl

Where can I register ENUM domain within 8.4.e164.arpa zone?

ENUM domains may be registered through entities which have concluded an appropriate agreement on cooperation with NASK. Currently, only one entity assists in registration of ENUM domains, namely:

Agnat Sp. z o.o.
ul. Gdańska 119
85-022 Bydgoszcz, Poland
phone: +48.523667777, +48.523667788
email: bok@domena.pl

Questions regarding a registration procedure and price list should be referred directly to the entity specified above.

ENUM browser

Enter below a requested phone number and press „Check” to search the ENUM database