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ENUM Check

Please enter a complete number (including country and area code) with a "+"-sign
in front (e.g. +4315056416).

ENUM – how it works

 

The "ENUM" standard links telephone numbers with internet addresses using the DNS (Domain Name System). For this purpose a globally unique domain name is assigned to each telephone number as follows:

  1. +43 1 5056416 (Specification of the complete telephone number)
  2. 4315056416 (Removal of all characters except numbers)
  3. 6146505134 (Reversal of the number order)
  4. 6.1.4.6.5.0.5.1.3.4 (Insertion of dots between the numbers)
  5. 6.1.4.6.5.0.5.1.3.4.e164.arpa (Adding the global ENUM domain e164.arpa)

Special DNS entries ("NAPTR-Records") are stored for this domain name, which specify the services available for a telephone number. According to the above example the DNS query returns the following entries:

 

6.1.4.6.5.0.5.1.3.4.e164.arpa NAPTR 100 10 "u" "E2U+sip" "!^.*$!sip:office@enum.at!" .

6.1.4.6.5.0.5.1.3.4.e164.arpa NAPTR 100 10 "u" "E2U+web:http" "!^.*$!www.enum.at!" .

 

According to this, the telephone number +43 1 5056416 is linked with the (SIP) internet address sip:office@enum.at as well as the web address http://www.enum.at/. Both addresses represent an alternative communication possibility in addition to the "classical" phone call. This information allows a SIP-based VoiP telephone to forward a call to this number directly via internet. In addition, the specified website can be displayed on the hardware device (as long as this is supported).

 

As a matter of course, the procedure as shown above must not be performed manually by the user himself: Similar to conventional telephones the user only enters the phone number, and the necessary technical processes are carried out "in the background" by the end device or by the service provider.

 

Apart from both described possibilities for ENUM services, several other services have been registered with IANA - and the IETF constantly develops new ENUM-based services. Creativity is nearly unlimited in this regard - it is possible to link almost any information via the ENUM technology.

 

At the moment ENUM is mostly used in connection with Voice over IP (VoIP). Further information about this is can be found here.