Measures against impersonation of identity through telephone calls and messages

The regulatory framework for fraud prevention measures has been strengthened by Order TDF/149/2025, of 12 February, establishing measures to combat phishing scams through fraudulent telephone calls and text messages and to ensure the identification of the numbering used for the provision of customer services and the making of unsolicited commercial calls, laying down additional obligations for operators with regard to blocking traffic, use of numbering and identification of the line of origin.

One of the main measures of Order TDF/149/2025 is to prevent a call from displaying a telephone number that cannot legitimately be used as a caller ID.

For this reason, operators must block, among others, calls that:

• do not have any number as a calling line identifier (CLI);
• use a Spanish number that has not been assigned to provide a service;
• use numbering that has been assigned to an operator but has not yet been assigned to any customer;
• enter Spain from another country showing a Spanish number as an identifier, except when it is a call made on international roaming.

Operators must block messages that use numbering that cannot legitimately be used as the sender’s identifier. They must also block messages that enter Spain from abroad by displaying a Spanish number, except in cases of international roaming.

• Messages can also be identified by an alias, for example, the name of a company or an Administration instead of a phone number.
• To prevent these identifiers from being used to impersonate a company or entity, the regulation establishes an Alias Registry managed by the National Commission of Markets and Competition (CNMC).
• Aliases must be registered in this Registry and can only be used by courier providers who are authorized to do so. Messages that use an unregistered alias, or that come from a provider that is not authorized to use it, must be blocked.
• The obligations related to the Register of Alias are effective from September 15, 2026, according to the modification introduced by the Order TDF/558/2026.
• The information on the Alias Registry and the procedure for registering an alias can be found in the CNMC website.