A registrant must prove they are the end user of the telephone number and entitled to the ENUM registration. This process is called validation.

Registrars must carry out this process on behalf of registrants as part of the registration or renewal process. This can be done by sending data to a validation agency (VA) who then validates this usage. It is also possible for the registrar itself to be a validation agency. If, as an ENUM registrar you already provide telecommunication services to the registrant, you can self-validate ownership of the telephone number without using an external validation agency. In order to act as registrar and VA, you must also be accredited as a VA by UKEC.

The validation process can be done in a number of ways:

1. A Directory Enquiries (DQ) lookup.
2. A multi-part text message that the prospective registrant types into a web site.
3. A private lookup into a Communications Provider (CP) database of customers.
4. Phone bill or other document from the CP proving ownership of telephone number range.
5. Any other mechanisms that meet the principles detailed in the UK ENUM Trial Group Report (pdf)  (especially sections 5.3 and 11.2).

The VA then provides a validation token to the registrar confirming ownership of the number range. To complete registration, the registrar presents the token to the registry. The VA token includes data saying who the registrar is, which must match the registrar who submits the request.

Fig.1  Diagram showing ENUM validation process

• Registrant supplies details to registrar
• Registrar forwards them to validation agency (VA)
• VA checks ownership of number - replies with token
• Registrar sends request to registry with VA token
• Registry creates registration - for one or more numbers
• Registry delegates numbers in 4.4.e164.arpa zone