Alias Registration with the CNMC: What Your Company Needs to Know Before June 7, 2026

If your company sends SMS with a customized sender name (known as alias or Sender ID), you have a critical date ahead: June 7, 2026.

From that moment, the CNMC (National Commission of Markets and Competition) requires all aliases to be registered in their official Registry. Messages with unregistered aliases will be automatically blocked by operators, without exceptions.

In this guide, we explain what SMS alias registration is, what the regulations say, how to process the registration step by step, what technical requirements the CNMC demands, and how Acumbamail can help you manage the entire process.

What is the CNMC Alias Registry for SMS Senders?

The Alias Registry is an official database managed by the National Commission of Markets and Competition (CNMC) where all alphanumeric senders (aliases) used in SMS, MMS, or RCS messages sent to Spanish numbers must be registered.

An alias is the text string that appears as the sender on the recipient’s mobile instead of a phone number. For example: “MyCompany”, “BankXYZ”, or “Correos”. Until now, any company could use them freely. With the new regulations, only registered aliases linked to their legitimate owner can be sent.

The legal framework regulating this obligation is the Order TDF/149/2025, of February 12, developed by the CNMC Circular 1/2026, published in the BOE on March 27, 2026.

Why was this regulation created? To tackle the smishing problem

The origin of this regulation lies in the exponential growth of smishing or phishing via text messages: identity theft through SMS. Scammers sent messages posing as banks, parcel companies, or public administrations using the name of those entities as the sender. Anyone could write “BBVA” or “Correos” in the sender field without any control.

With the SMS Alias Registry, the CNMC closes this door: only the legitimate owners of each name can register it, and only messages sent through an authorized provider linked to the alias will reach the recipient.

Además del registro, la CNMC habilitará un portal público de consulta donde cualquier ciudadano podrá verificar a quién pertenece cada alias. Una capa extra de transparencia que refuerza la confianza en el canal SMS.

Key Dates: When It Comes Into Effect

The implementation schedule is strict. There is no room for improvisation, especially because the validation process can take up to three months in the initial phase:

• March 18, 2026: Approval and publication of Circular 1/2026 in the BOE.
• From now: The Registry is already operational at the CNMC Electronic Headquarters. You can process the registration of your aliases today.
• April 2026: Mass loading phase. Origin providers (PRO) can pre-register the aliases their clients already use in bulk.
• Until June 6, 2026: Testing environment and system adaptation for operators and providers.
• June 7, 2026, the deadline: Full entry into force. Operators will automatically block any message with an unregistered alias or sent by an unauthorized provider.

⚠️ Important: During the first six months from the publication of the Circular, the maximum validation and registration period by the CNMC is three months. After this transitional period, the ordinary period will be one month. If you register your alias late, it may not be validated in time.

Technical Requirements for the Alias: Format Allowed by the CNMC

Circular 1/2026 establishes precise format rules. Your alias must comply with them to be accepted in the registry.

General Rules for SMS and MMS

• Length: minimum 3 characters, maximum 11 characters.
• Allowed characters: letters (a-z, A-Z, including ñ and ç) and numbers (0-9).
• Exclusively numeric aliases are not allowed.
• Uppercase/lowercase: the same alias cannot be registered by varying only the capitalization to avoid impersonation.

Allowed Special Characters

Only the following special characters are allowed: space (never at the beginning, end, or two consecutive), at [@], ampersand [&], dot [.], hyphen [-], underscore [_], and plus sign [+].

Prohibited Characters and Names

Accented characters and symbols such as ¡! ¿? # % * , ; : () [] / = € are not allowed. Generic aliases like “Message,” “Bank,” or “Urgent” are also not accepted, nor are personal or place names without direct linkage to the company (for example, “Madrid” is not allowed, but “AytoMadrid” is).

How to Register Your Alias with the CNMC? Step by Step

The process is handled at the CNMC Electronic Headquarters using a digital certificate or Cl@ve. For a message to reach the recipient from June 7 onwards, two simultaneous conditions must be met:

1. The alias must be registered in the CNMC’s official database and linked to its legitimate owner.
2. The sending provider must be authorized as a Registered Origin Provider (PRO) for that specific alias.

These are the steps to process the registration:

1. Identify all your active aliases. Make a complete list of the sender names you use in your SMS shipments to Spain.
2. Choose the linking criterion. The CNMC requires proof that the alias belongs to you. You can do this through: registered trademark at the OEPM or EUIPO, corporate name (deeds or certificate from the Commercial Registry), or ownership of a related internet domain.
3. Prepare the documentation. Have the certificates or deeds available that prove the legitimate link with the alias.
4. Process at the electronic headquarters. Access the CNMC registration form with a digital certificate or Cl@ve. You can register multiple aliases in a single application.
5. Sign the responsible declaration. The official model where you state that the use of the alias is legitimate.
6. Link your provider as PRO. Formally authorize your sending platform to be enabled to send messages under that alias. Without this step, messages would be blocked even if the alias is registered.

Does It Also Affect International Shipments?

Yes, and this is a point many companies overlook. The regulation is especially strict with international SMS traffic. From June 7, 2026, any message sent from abroad to Spanish users using an alias not registered with the CNMC will be automatically blocked.

If your company operates globally but sends communications to clients in Spain, it is mandatory that your sending routes are regularized and your aliases registered in the CNMC Registry, regardless of where the messages originate. If the recipient is roaming, the operator must replace the alias with the mention “NOT VALIDATED.”

Who Needs to Register? Company, Reseller, or Agency

If you are the alias owner (company or public administration)

You are responsible for registering your alias and authorizing the provider that will send it. You can process it directly or delegate to an authorized third party, such as your sending platform.

If you are a reseller or agency

You can act as an authorized third party and manage requests on behalf of your end clients. However, each client must provide their express authorization, as the CNMC will notify the owner to approve the registration within 10 business days.

How Can Acumbamail Help You?

At Acumbamail, we are a Registered Origin Provider (PRO) with the CNMC. This means we can send SMS messages on your behalf once your alias is registered and you have authorized us as an enabled provider. Without this linkage, even if you have the alias registered, your messages would still be blocked.

• Registration processing on your behalf. Our team can manage the registration of your aliases at the CNMC Electronic Headquarters acting as an authorized third party.
• Mass loading of aliases. If you already send with us, we facilitate the grouped pre-registration of all your active senders during the transition period.
• Continuous synchronization with the CNMC. Our systems regularly connect with the official database to keep your routes validated and avoid accidental blocks.
• Delivery guarantee. Only messages sent through a PRO enabled for the alias will pass the operators’ filters. With Acumbamail, your SMS reach their destination.
• Proactive alerts. We notify you of any status changes in your aliases so you’re never caught off guard.

Frequently Asked Questions About the SMS Alias Registry

How many aliases can I register?

There is no limit, as long as each alias meets the format criteria and you can prove a legitimate link with each one. Additionally, you can include multiple aliases in a single registration application.

What happens if I don’t register my alias before June 7?

Your SMS messages will be automatically blocked by operators and will not reach your recipients. Additionally, non-compliance may result in financial penalties in accordance with the General Telecommunications Law.

Do I need to register the aliases I use for international shipments to Spain?

Yes. The regulation applies to all messages directed to Spanish numbers, regardless of their geographic origin. If you send from another country to Spain with an alias, that alias must be registered in the CNMC Registry.

Does it also apply to RCS messages?

Yes. Circular 1/2026 expressly includes RCS (Rich Communication Services) messages, in addition to traditional SMS and MMS. For RCS, clear identification requirements of the alias with the brand, trade name, corporate name, or domain of the owner also apply.

Can I continue using my current alias or do I need to change it?

If your alias meets the format requirements and you can prove the legitimate link, you can continue using it once registered. You will only need to change it if it contains prohibited characters, exceeds 11 characters, or is a generic term rejected by the CNMC.

In Summary: Act Now, Not on June 6

The CNMC SMS Alias Registry is not optional. From June 7, 2026, unregistered aliases will be out of the system. Considering that validation can take up to three months in the initial phase, the real margin to act is running out.

If your company uses SMS for order confirmations, alerts, transactional notifications, or marketing campaigns in Spain, this procedure is urgent.

Do you have questions about which aliases you need to register, what documentation to prepare, or how to manage the process? Our team is available to help you audit your senders and process the registration. Write to us and we'll solve it together.