Spain | Registering your Sender ID (Alias) with the CNMC National Alias Registry

September 21, 2026 06:10 Updated

Enforcement is now live. Since 15 September 2026, Spanish operators block any SMS, MMS, or RCS message sent to a Spanish (+34) number using an alphanumeric Sender ID that is not registered and approved in the CNMC National Alias Registry. The original date was 7 June 2026 and was extended to 15 September.

If you send to Spain with an alphanumeric Sender ID and you have not registered it, your traffic is affected today. If you cannot register, a dedicated Spanish number will keep your messages delivering. Both paths are covered below.

What's changing and why

The Spanish National Markets and Competition Commission (CNMC), under Ministerial Order TDF/149/2025, operates a National Alias Registry for all alphanumeric Sender IDs used to send SMS, MMS, and RCS to Spanish mobile numbers.

The registry exists to reduce SMS impersonation fraud, known as smishing, and to give Spanish subscribers a traceable origin for every branded message they receive. The rule applies to every sender reaching +34 numbers, Spanish or foreign.

Numeric senders, meaning long codes and short codes, are not covered by the registry and are not affected.

You will be able to register your Sender ID directly with the CNMC, to avoid disruption.

Who this affects

You need to act if all of the following are true:

You send messages to Spanish (+34) mobile numbers, and
You use an alphanumeric Sender ID, for example YOURBRAND, as the sender, and
That Sender ID is not registered and approved in the CNMC registry.

Sinch is your Registered Provider of Origin (PRO), the regulated carrier of record. The CNMC requires you, the alias holder, to register each alias directly, because the registry needs your legal entity details, an authorised legal representative, and a digital signature that only your organisation can provide. We cannot do this on your behalf.

What happens to unregistered traffic

Messages sent to Spain with an unregistered alphanumeric Sender ID will not be delivered. You will see delivery failures until the alias is registered and approved, or until you move the traffic to a dedicated Spanish number.

If you cannot register: move to a dedicated Spanish number

This is the recommended path if any of the following apply:

You are outside the EU or Schengen area and cannot obtain a compatible digital certificate.
Your legal or procurement process cannot produce an authorised representative with a digital certificate.
Your registration has been rejected and you need delivery restored now.

Numeric senders are not covered by the alias registry and continue to deliver to Spanish mobile numbers without registration.

What you get

Uninterrupted delivery to Spain with no registration burden.
A number your recipients can reply to, which is useful for two-way use cases.
No digital certificate requirement.

Trade-offs

Messages display a numeric sender rather than your brand name.
There is a monthly rental for dedicated numbers.
Opt-out and content rules for Spanish traffic still apply.

How to request one

Log in to your Sinch Engage account and go to Settings, then Numbers, then Dedicated Numbers, and click Add a Number. If you would like help choosing, contact your Account Manager or the International Sender Team.

Outside the EU or Schengen?

Start with a dedicated Spanish number. The CNMC portal requires a digital certificate or national eID recognised by the Spanish authorities, and these are issued to EU and Schengen residents and entities. If your country does not issue one, you cannot log in to the portal to submit a registration at all.

There is a route for non-EU entities via an FNMT certificate, which requires your company documentation, including certificate of incorporation and power of attorney, to be apostilled under the Hague Convention and translated into Spanish by a sworn translator. Allow 6 to 8 weeks. Given that enforcement has already started, this is only worth pursuing if you have a long-term need for the alias, and you should move to a dedicated number in the meantime.

Quick test: go to tramites.cnmc.gob.es/formulario/213 . If you can log in, you can register. If you cannot, a dedicated number is your path.Step-by-step registration guide

Before you start - you will need

Your company legal details: legal name and NIF, CIF, or VAT ID.
A nominated legal representative: full name, NIF or equivalent, email, mobile. This person must hold the digital certificate or eID. They will receive the authorisation email and they are the only person who can action it.
A digital certificate or national eID accepted by the Spanish portal. Install AutoFirma from the Spanish Government e-administration site and validate your certificate at VALIDe. If your certificate is not accepted you can request one from FNMT.
For each alias: the channel, the use case, an activation date, an optional end date, and the basis for your legitimate link to the alias.
The details of any third party that transmits traffic on your behalf. See the third parties section below.

Alias naming rules

Length: 3 to 11 characters.
Allowed: a to z, A to Z, ñ and Ñ, ç and Ç, 0 to 9, space, and @ & - . +
Not allowed: leading, trailing, or consecutive spaces, accents, # % ( ) , / : ; < > = ¡ ! ¿ ? [ ] €, or an alias made only of digits.
Prohibited: impersonating public authorities, trivial variants of an already registered alias, or an alias with no link to your brand, domain, or legal entity.

Case matters. Register the alias exactly as you send it. YOURBRAND and Yourbrand are treated as different strings, and a mismatch between what is registered and what we send can cause a block.

Before you open the portal, three practical things

The portal is in Spanish only. There is no English option. A browser translation extension helps.
It logs you out after 4 to 5 minutes even while you are actively typing. Click GUARDAR BORRADOR to save a draft and return to it rather than losing your work.
Set a calendar reminder for the authorisation email now, before you start. This is the single most common reason registrations fail. See "Why registrations get rejected" below.

Step by step

Open the registration form. Go to tramites.cnmc.gob.es/formulario/213 and log in with your digital certificate or national eID.
Say who is submitting. Choose En nombre propio if you are self-employed or a freelancer. Choose En representación de if you are a company, or a third party submitting on behalf of a brand owner. Most customers use En representación de.
Enter the alias holder. Your company legal name and NIF, CIF, or VAT ID. This must be the legal entity that owns the brand the alias represents, not your agency or platform provider.
Enter the address. Complete the address section. It appears optional but becomes mandatory later, and changing the request type afterwards clears what you have entered, so do it in order.
Select the request type. Choose Inscripción de Alias.
Add the representative of the alias. Choose Persona jurídica if the representative is a company, or Persona física if it is an individual. Tick Recibir notificaciones so the authorisation email is sent. Give the NIF of the person who holds the digital certificate, because only that person can authorise the request later.
Add each alias. Click Añadir alias, enter the alias exactly as you send it, and choose Tipo de mensaje. You can only select one channel per request. If you need the same alias for both SMS and RCS, submit two separate requests.
Set the dates. F. Activación is when the alias should become active. F. Fin is optional and is the deactivation date, up to 24 months from activation.

State your legitimate link (Vinculación legítima). Choose the option that matches how you own the name:

Option	What it means	When to use it
`Marca registrada ante la OEPM o la EUIPO`	Trademark registered with the Spanish Patent and Trademark Office or EUIPO	The brand is registered with either body
`Nombre comercial registrado ante la OEPM`	Trade name registered with the OEPM	Registered with the Spanish trademark registry
`Denominación social reconocida legalmente en el Registro Mercantil`	Company name in the Spanish Commercial Register	Your company is registered in Spain
`Dominio de internet registrado en Red.es o por la ICANN`	Internet domain registered with Red.es or ICANN	The alias is an internet domain you own
`Denominaciones inscritas en otros registros públicos nacionales o internacionales`	Registered in another national or international public registry	Your company is registered outside Spain, for example Companies House or ASIC. Name the registry
`Uso de alias de forma legítima y habitual en el desarrollo de la actividad profesional`	Legitimate and habitual professional use	Only when none of the above apply. Give a full reason

Pick the strongest basis you can evidence as failure to do so can result in rejection.

Add Sinch as your Provider of Origin. Search for the Sinch entity, click it, then click AÑADIR PROVEEDOR to attach it. Selecting it without clicking the add button leaves it unattached and the request will not submit correctly.
Add any third parties (TERCEROS). See the section below. Skip this only if nobody transmits Spain traffic on your behalf.
Review and submit. Tick the declaration and click REVISAR Y PRESENTAR. Errors are reported in Spanish. Check the summary, tick the confirmation, and click PRESENTAR.
Authorise within the deadline. Your nominated representative receives an email from the CNMC. They must log in, select Autorización de alias, choose Autorizar, restate the Vinculación legítima, tick Acepto, and submit. If this is not actioned in time, the registration is automatically declined and you must start again.
Tell us. Email internationalsending@smb.sinch.com with your CNMC confirmation, your account details, and the alias exactly as registered. Registration with the CNMC alone is not enough. We hold a separate list of approved senders, and until your alias is on it your traffic can still be blocked at our end.

Frequently asked questions

I only send to Spain from a numeric sender. Do I need to do anything? No. Numeric long codes and short codes are not covered by the registry.

Can Sinch register on my behalf? No. The registry requires your legal entity details and a digital signature from your nominated representative, and that signature cannot be delegated to us. You register directly and then tell us.

What happens now if I have not registered? Messages sent to Spain with an unregistered alphanumeric Sender ID will not be delivered. You will see delivery failures until the alias is registered and approved, or until you move the traffic to a dedicated Spanish number.

My organisation is outside the EU. Can I still register? Only if your representative holds a digital certificate or eID accepted by the Spanish portal. Many countries outside the EU and Schengen area do not issue one, in which case you cannot log in to submit at all. A dedicated Spanish number is the recommended path.

How long is a registration valid for? Up to 24 months from the activation date you nominate. You can renew before expiry.

Can I register the same alias for SMS and RCS? Yes, but they are two separate submissions. The form only accepts one channel per request.

My alias is approved with the CNMC but my messages are still blocked. Why? Two common causes. Either you have not told us yet, and the alias is not on our approved sender list, or the alias you registered does not exactly match the string we are sending, most often a difference in capitalisation. Email us the alias exactly as it appears in the CNMC portal and we will check both.

Where does "SINCH SPAIN" come from? Sinch is your Registered Provider of Origin for traffic routed through the Sinch platform. Search for and add the Sinch entity in the Proveedor section of the form.

Need help?

International Sender Team: For Sender ID (Alias) registration inquiries Email: internationalsending@smb.sinch.com
CNMC form: tramites.cnmc.gob.es/formulario/213

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