How to register your Spain SMS branded sender ID directly with the CNMC

Spain's telecommunications regulator (CNMC) now requires all businesses sending SMS to Spanish phone numbers using an alphanumeric (branded) sender ID to register that sender ID in a national registry. From September 15, 2026, any unregistered sender ID will be blocked by Spanish carriers; this applies to all businesses sending to Spanish numbers, regardless of where the business is based.

The CNMC has communicated that direct registration, submitted by you through their portal, is the fastest path to approval, with a processing time of approximately one month. Based on this guidance, Klaviyo is encouraging all customers who need to meet the September 15, 2026 deadline to register directly rather than waiting for a third-party submission. The CNMC's processing timelines for registrations submitted through aggregators and carriers are outside Klaviyo's control, and direct registration puts approval squarely in your hands. This guide walks you through every step.

Before you start: Obtain your digital certificate

You cannot access the CNMC portal without a valid digital certificate. Which type you need depends on where your company is registered.

If your company is registered in Spain: FNMT certificate

Spanish companies use a certificate issued by the FNMT (Fábrica Nacional de Moneda y Timbre, Spain's national mint). The end result is a certificate file you download and install on your computer.

How to obtain it:

1. Go to https://www.sede.fnmt.gob.es/certificados/certificado-de-representante and select the certificate type for your entity. Most companies (S.A., S.L., and similar) should select "Representante de Persona Jurídica."
2. Install the software required by the FNMT before submitting your application. Instructions are provided on the configuration page.
3. Submit the online application. You will receive a request code by email.
4. Verify your identity. For most standard company types (NIF starting with A, B, C, or D), online identity verification is available and recommended — you can complete this step without visiting an office. Some other entity types require an in person appointment at an AEAT office.
5. Approximately one hour after verification, download and install your certificate on the same device and browser you used to apply. The certificate costs €14 plus tax and is valid for 2 years.

Timeline: Most companies can complete this fully online within a few days.

If your company is registered in an EU member state (but not Spain)

The CNMC portal requires a digital certificate issued by a provider on Spain's Ministry of Economic Affairs approved list. You can view the full list at https://sedeaplicaciones.minetur.gob.es/prestadores/.

Most EU-recognised Qualified Trust Service Providers (QTSPs) appear on this list. Obtain a qualified electronic signature certificate from your country's national QTSP, or check the Ministry list above to confirm your provider is accepted before purchasing.

Look for a Qualified Electronic Signature (QES) certificate product. Standard SSL or S/MIME certificates are not sufficient.

Timeline: Allow 1 to 3 weeks depending on your provider.

If your company is registered outside the EU (including US, UK, and Australia)

The only internationally accessible provider confirmed on Spain's Ministry registry is Sectigo (sectigo.com). You will need to obtain a Sectigo eIDAS-qualified electronic signature certificate. When purchasing, look specifically for their Qualified Electronic Signature (QES) product — standard SSL or S/MIME certificates from Sectigo are not sufficient and will not be accepted by the CNMC portal.

Note that DigiCert, GlobalSign, Certigna, and D-Trust do not appear on Spain's Ministry registry and their certificates will not be accepted.

Installing your certificate for use with the CNMC portal

The CNMC portal works with certificates installed in your browser or operating system certificate store. After obtaining your certificate:

• Windows: Import the certificate via Internet Explorer / Edge certificate manager, or through the Windows Certificate Store. Firefox users need to import separately via Firefox Settings > Privacy & Security > Certificates.
• Mac: Import the certificate into Keychain Access. Safari and Chrome will pick it up automatically. Firefox users need to import separately.

Test your certificate works by logging in to the CNMC portal before filling in the registration form. If the portal does not recognise your certificate, contact your certificate provider's support team.

Step 1: Access the CNMC Alias Registry portal

Go to the CNMC Alias Registry portal and log in using your digital certificate.

Portal URL: https://tramites.cnmc.gob.es/formulario/213/

Alternatively, you can access the portal via the CNMC's electronic sede at https://sede.cnmc.gob.es/tramites/telecomunicaciones/gestion-del-registro-de-alias.

Step 2: Fill in your Applicant details (Solicitante)

You are registering on behalf of your company, so select:

"On behalf of" / En representación de

Fill in the following fields:

For Request Type (Tipo de Solicitud), select:

Alias Registration / Inscripción de Alias

Step 3: Add your Legal Representative (Representantes del titular)

Click "Add Representative" / "Añada representante".

This is the person (or legal entity acting through a person) who will receive a confirmation request from the CNMC and must respond within 10 business days. Give them a heads-up before submitting. If they miss the window, your registration will be rejected.

Choose Natural Person if your representative is an individual:

Choose Legal Entity if your representative is a company (e.g. a holding company or parent entity):

Step 4: Fill in your Alias (sender ID) details

Note: The specific allowed character list above is sourced from Infobip's registration guidance. For the most current technical specification, refer to CNMC Circular 1/2026.

Legitimate Linkage (Vinculación legítima): Choose the option that best describes your connection to the sender ID name. Select only one:

• Registered trademark (OEPM or EUIPO): select this if your sender ID is a registered trademark
• Trade name (OEPM): select this if it is a registered commercial name
• Corporate name (Companies Register): select this if it matches your legal company name
• Internet domain (Red.es or ICANN): select this if it matches a domain registered in your company's name
• Other national/international registries: select this if registered elsewhere
• Legitimate and habitual use: select this only if none of the above apply. You will need to provide a written explanation of how and why you use this sender ID

In the Specify the legitimate connection (Especificar cuál es) field, enter the exact trademark name, domain name, corporate name, or (for legitimate use) your explanation.

Step 5: Select Infobip as your Provider

In the Providers (Proveedores) section, search for and select:

INFOBIP LIMITED

This must be selected exactly as written above. Infobip is Klaviyo's carrier partner for Spain SMS delivery. Selecting the correct provider name is essential. If this field is blank or incorrect, your registration will not be linked to your Klaviyo sending and your traffic may be blocked even if the registration is approved.

Step 6: Add Klaviyo as a Third Party

The CNMC requires you to identify any platform or technology provider that manages or uses your sender ID on your behalf, and this includes Klaviyo.

Click "+ Add third party" / "+ Añadir tercero" and select Legal Entity.

Enter the following details exactly:

Why this matters: Klaviyo is the platform through which your SMS traffic is managed and sent. Listing Klaviyo as a third party is required for regulatory traceability. If Klaviyo is not named here, the CNMC may flag your registration as incomplete.

Step 7: Review and submit

Click "REVIEW AND SUBMIT" / "REVISAR Y PRESENTAR".

Review all details carefully before submitting. Common mistakes that cause rejections:

• Infobip not selected as the Provider, or selected with a different spelling
• Klaviyo not listed as a Third Party
• Sender ID contains disallowed characters or exceeds 11 characters
• Legitimate linkage documentation does not match the sender ID name
• Legal representative details are incomplete or incorrect

Once submitted, the CNMC will send a confirmation request to your listed legal representative. They must respond within 10 business days or the registration will be rejected and must be restarted.

After submission

You do not need to notify Klaviyo separately once you have registered directly. Your registration is tied to your sender ID and Infobip as provider, which covers your Klaviyo sending.

If your registration is rejected, you will receive an email from the CNMC with the reason. Contact Klaviyo Support for help preparing a corrected resubmission.

Sources: CNMC's official sede at sede.cnmc.gob.es, CNMC Circular 1/2026, AWS End User Messaging documentation, Infobip registration guidance.