In many companies, SMS remains a common way to communicate with customers, users or suppliers: appointment confirmations, delivery notifications, verification codes, commercial notices, payment reminders…
However, when these messages are sent identifying the sender with a commercial name, a brand or a company name, it is no longer enough for the technology provider to manage the delivery. That identifier, known as an alias, must be properly registered in the Alias Registry managed by the CNMC, the Spanish National Markets and Competition Commission.
Circular 2/2026 introduces important adjustments to this registry. Although the update may seem very technical, it has a clear practical consequence: companies that use aliases in SMS, MMS or RCS messages addressed to Spanish numbers should review whether they comply with the new system before blocking measures begin.
What is an alias and why does it matter?
An alias is the name that appears as the sender of a message. For example, when a person receives an SMS from a bank, a transport company, a clinic, an insurance company or an online store, the sender may appear as an alphanumeric string instead of a telephone number.
The problem is that this system can also be used to impersonate identities. For this reason, the Alias Registry seeks to prevent any third party from sending messages while appearing to be a legitimate company.
In practice, if a company uses an alias to send communications to Spanish numbers, that alias must be registered and linked to the messaging providers authorised to send messages on its behalf.
Which companies may be affected?
The obligation is not limited to large companies or highly regulated sectors. It may affect any company that uses SMS, MMS or RCS with an alphanumeric alias as the sender.
This includes, among other cases, companies that send:
- verification codes or two-factor authentication messages;
- order, appointment or booking confirmations;
- delivery notices or logistics incident updates;
- commercial communications;
- payment reminders or service notifications;
- information notices to customers or users.
It may also affect foreign companies that want to send messages with an alias to Spanish numbers, especially when they do not have a Spanish digital certificate or need to act through an authorised representative.
What changes with Circular 2/2026?
Circular 2/2026 modifies the initial regulation of the Alias Registry to facilitate its practical application. Among the main updates, it allows alias holders to act through authorised representatives, makes certain procedures before the CNMC more flexible and enables the bulk upload of aliases by originating providers in specific cases.
This change is relevant because many companies do not manage their SMS sending directly. Instead, they do so through operators, aggregators, technology platforms or external providers. In addition, for foreign companies, the requirement to have a Spanish digital certificate could become a significant operational barrier.
Key date: 15 September 2026
Although the system is already in place, the date companies should keep in mind is 15 September 2026. From that date, operators must block SMS, MMS or RCS messages that use unregistered aliases or that are sent by providers not authorised for that alias.
The risk, therefore, is not only formal. If a company does not review its situation in time, it may find that certain legitimate communications do not reach their recipients. In this case, anticipation is key.
From LEIALTA’s corporate legal department, we help companies analyse their corporate and regulatory obligations, as well as manage procedures before public bodies when required by their business operations.
