How to register a Spanish branded sender ID
Spain SMS Sender ID Registration
Spain's telecommunications regulator (CNMC) now requires all businesses sending SMS to Spanish phone numbers using a branded (alphanumeric) sender ID to register that sender ID in a national registry. Starting September 15, 2026, any unregistered sender ID will be blocked in real time by Spanish carriers, meaning your SMS campaigns and flows will not reach Spanish recipients until registration is complete. Klaviyo will proactively block traffic to preserve SMS credits and your deliverability.
This article explains your two options for getting registered, what you'll need, and how to decide which one is right for your account.
Is my account affected?
You are affected if both of the following apply:
- You send SMS to recipients with Spanish phone numbers (+34)
- You use an alphanumeric (branded) sender ID — for example, "YourBrand" rather than a short code or long code
Not affected: Numeric sender IDs (short codes and long codes) are outside the scope of this regulation and do not require registration.
If you're unsure which sender ID type your account uses, check Settings > SMS in Klaviyo.
Your two options
You only need to complete one of the following, not both.
Option A: Register directly with the CNMC | Option B: Register through Klaviyo | |
|---|---|---|
Who submits | You, via the CNMC's own portal | Klaviyo, on your behalf. |
Eligibility | Spanish companies, or international companies that can obtain a qualifying digital certificate | All customers |
Typical timeline | Faster, you control submission timing | Dependent on Klaviyo/Infobip's process; timeline not guaranteed given ongoing regulatory changes |
Effort required | Medium, you fill out the CNMC portal yourself | Low, you submit your details to Klaviyo once |
Best for | Customers who want the most direct control over timing, or who need to be registered as soon as possible | Customers who prefer a managed process and can tolerate an uncertain timeline |
What you need to register
The information required is the same regardless of which option you choose. Have the following ready before you start. All information must be accurate — incomplete or incorrect submissions are a common reason for rejection.
Your sender ID
- Sender ID name: the branded name you send SMS from in Spain, must be 3–11 characters
- Allowed characters: letters a-z, A-Z (including ñ and ç), numbers 0-9, space, @, &, -, _, ., +
- Not allowed: purely numeric strings, accented vowels (á, é, í, ó, ú), or special characters such as !, ?, #, %, *, (, )
Your company details (alias holder)
- Holder type: whether you are registering as a Legal Entity (company) or Natural Person (individual)
- Registered name: your official company name (Legal Entity) or first name + surname(s) (Natural Person)
- Tax ID:
- Legal Entity registered in Spain: your Spanish company tax ID (NIF / CIF)
- Natural Person: your Tax ID, NIE, or passport number
- Companies registered outside Spain: CNMC guidance on this has narrowed recently — the current direction is to provide a NIF or a valid EU VAT ID where possible. If your company doesn't have either, contact Klaviyo Support to confirm the currently accepted alternative before submitting, since this detail has changed more than once in the last month.
- Registered address and country
Your legal representative
The details required depend on whether your representative is an individual or a company.
- If the representative is a Natural Person (individual): their Tax ID / NIE / Passport number, full name, surname(s), and email address
- If the representative is a Legal Entity (company): company tax ID and registered name, plus the details of the individual acting on its behalf: their Tax ID / Passport number, full name, and surname(s)
Whichever option you choose, your legal representative will need to confirm the registration through the CNMC portal — see the digital certificate note below.
Proof of brand connection
You must demonstrate a legitimate connection between your company and the sender ID. Provide one of the following:
- Registered trademark (OEPM or EUIPO)
- Trade name or commercial name registration
- Corporate name registration
- Internet domain registered in your company's name
If none of the above apply, you may declare "habitual/legitimate use" — in this case, a written explanation of how and why you use the sender ID is required in place of a document.
Responsible Declaration document
A signed Responsible Declaration (digitally signed by your legal representative) is required. Klaviyo provides the template in English and Spanish — contact Klaviyo Support to request it.
Digital certificate
Your legal representative needs a valid digital certificate to access the CNMC portal and confirm the registration — this applies under both options, since the CNMC contacts your legal representative directly to verify the registration regardless of who submits.
- Spanish companies use the FNMT certificate (issued by Spain's national mint and stamp factory)
- Non-Spanish companies (including US, UK, Australian, and other international businesses) need an eIDAS-qualified electronic certificate from a provider on Spain's Ministry of Economic Affairs approved registry (sedeaplicaciones.minetur.gob.es/prestadores/)
For non-EU companies specifically: the only internationally accessible provider currently confirmed on Spain's Ministry registry is Sectigo — look specifically for their Qualified Electronic Signature (QES) product; standard SSL or S/MIME certificates are not sufficient. Providers such as DigiCert, GlobalSign, Certigna, and D-Trust do not currently appear on Spain's Ministry registry, and certificates from them will not be accepted for this purpose.
EU-based companies can use their own country's national Qualified Trust Service Provider (QTSP), provided it appears on Spain's Ministry list.
Contact Klaviyo Support for guidance if you're unsure where to start.
Option A: Register directly with the CNMC
You submit your registration yourself through the CNMC's official portal. This gives you direct control over timing.
Two entries you must get right:
- Select Infobip as your Provider: this links your registration to Klaviyo's Spain sending infrastructure
- Add Klaviyo as a Third Party: Klaviyo's company name and Tax ID/registration ID are required here; see the full registration instructions for these details
Once submitted, the CNMC will contact your listed legal representative to confirm the registration. They have 10 business days to respond. If they miss this window, the registration will be rejected and must be resubmitted so give them a heads-up now so they know to expect it.
For a full field-by-field walkthrough, see our detailed guide: How to Register Your Spain SMS Sender ID Directly with the CNMC.
Option B: Register through Klaviyo
If you'd rather not manage the CNMC portal yourself, Klaviyo handles submission to the CNMC on your behalf.
How it works:
- Complete the Klaviyo registration form in your Klaviyo settings.
- Submit the form. Klaviyo passes your details to Infobip, who submits the registration to the CNMC Alias Registry.
- The CNMC contacts your listed legal representative directly to verify the registration via the CNMC portal. They have 10 business days to approve. If they don't respond in time, the registration will be rejected and must be resubmitted. Give them a heads-up to expect this notification and respond promptly.
- The CNMC reviews your registration. You'll receive an email notification when your registration is approved or rejected.
You can check your registration status at any time in your Klaviyo SMS settings.
A note on timing: CNMC's registration requirements have changed materially and repeatedly over the past several months, and Klaviyo doesn't control the CNMC's review process. We can't currently guarantee this path will complete before September 15. If meeting the deadline with certainty matters for your account, we recommend also considering Option A.
Register here
Which option should I choose?
- Choose Option A if you want the most control over your timeline, especially if you're close to the September 15 deadline and want to avoid depending on a third-party queue.
- Choose Option B if you'd prefer Klaviyo to manage the process for you and you're comfortable with some timeline uncertainty.
Registration statuses
Status | What it means |
|---|---|
Not submitted | No registration has been submitted for this sender ID. Action required. |
Pending | Your registration has been submitted and is under CNMC review. No action needed unless contacted. |
Active | Your registration is approved. You can continue sending to Spain with this sender ID. |
Rejected | Your registration was rejected. You will receive an email with the reason. Correct the issue and resubmit. |
Can I keep sending while registration is pending?
Yes, while your registration is in progress. However, once your registration status shows anything other than Active, Klaviyo will pause sending on that sender ID to Spain to protect you from carrier-level blocking, wasted SMS credits, and deliverability damage. If your registration is not approved before September 15, 2026, messages sent using an unregistered sender ID will also be blocked by Spanish carriers directly.
What happens if my registration is rejected?
Registrations are rejected by the CNMC for reasons such as:
- The sender ID does not meet format requirements (too long, disallowed characters, or purely numeric)
- No legitimate connection between the sender ID and the company could be verified
- The sender ID could cause confusion with another registered brand or public institution
- Required information was missing or inaccurate in the submission
If your registration is rejected, you'll receive an email with the reason. Correct the issue and resubmit — resubmissions go through the same review process and timeline. There is no expedited path.
Contact Klaviyo Support if you need help understanding the rejection reason or preparing a corrected submission.
Frequently asked questions
Does this regulation apply to me if I'm not based in Spain? Yes. The regulation applies to all businesses sending alphanumeric SMS to Spanish phone numbers (+34), regardless of where the sending company is based. See the digital certificate section above for what international companies need for either option.
What if I send to Spain using a short code or long code? Numeric sender IDs are outside the scope of this regulation. No action is required.
What if I have multiple sender IDs I use to send to Spain? Each sender ID must be registered separately, through either option.
Does this affect RCS as well as SMS? Yes. The CNMC registry covers both SMS and RCS alphanumeric sender IDs. If you send RCS to Spain using a branded sender ID, that ID must also be registered. Note: the character limit for RCS sender IDs is 3–40 characters (versus 3–11 for SMS).
Can I switch between options if one isn't working out? Yes. If you start with Option B and want more control over timing, you can pursue Option A at any point — you don't need to wait for or cancel your Klaviyo submission first.
How will I know when my registration is approved? The account owner will receive an email notification when the registration status changes. You can also check status at any time in your Klaviyo SMS settings.
What if my legal representative doesn't respond to the CNMC notification in time? The registration will be rejected. You will need to resubmit and go through the full process again, including the CNMC review period. Make sure your legal representative knows to expect a notification from the CNMC and responds within 10 business days.
I submitted my registration but haven't heard anything. What should I do? If you submitted via the Klaviyo intake form and have not received a confirmation, contact Klaviyo Support to verify your submission was received.
Need help?
Contact Klaviyo Support or visit the Help Center for additional guidance.
Last updated: July 8, 2026. Requirements are set by Spain's CNMC and are subject to change; this article reflects the most current information available at time of publication.
Contact Klaviyo Support for additional guidance.