SMS Alias Registration: Key Points from CNMC Circular 1/2026

Circular 1/2026 of 18 March from the Spanish National Markets and Competition Commission (CNMC), outlines the details of the Alias Registration system provided for in Order TDF 149/2025 of 12 February, and stipulates that, as from 7 June 2026, messages containing unregistered aliases must be blocked.

This circular regulates the creation of a prior registration system for alphanumeric aliases used as senders in SMS, MMS and RCS messages that do not allow direct replies, with the aim of reducing ‘smishing’ and impersonation via messaging, thereby providing greater security for users by helping them distinguish genuine messages from attempts at fraud.

As a general rule, if a company or public administration sends messages to Spanish numbers using an alias containing letters, it must register it beforehand. Registration will not be required when the sender is exclusively numeric (mobile, short number, etc.) or when the messages are addressed to recipients other than Spanish numbers.

The party required to register the alias with the CNMC prior to its use will be the company or public administration that owns the alias, the registered origin provider (PRO. its Spanish acronym) acting on behalf of the owner for sending and transmitting messages, or a third party authorised by the owner.

The alias is registered electronically via the CNMC’s online portal and requires proof of a legitimate link between the alias and its owner. Said link may be based on a registered trademark, a registered trade name, the company name, the internet domain or, where applicable, another name entered in a national or international public register.

The registration application must be accompanied by supporting documentation and the relevant declaration of responsibility. Once registered, the alias may only be used under the conditions set out in the circular, and any relevant changes must be kept up to date, for example, if the ownership or use of the alias changes.

Non-compliance may result in messages being blocked, disruptions to communication with customers and a significant reputational impact. It is therefore advisable to audit the aliases/senders used, separate numerical ones from alphanumerical ones, and prepare their registration – if they are subject to the regulation – before 7 June 2026.