Overview
From September 15 2026, any alphanumeric Sender ID (also known as an alias) must be registered in advance with the official Alias Registry operated by the CNMC (CNMC, Spain's National Commission for Markets and Competition). Use of these Alpha Tags must also be approved through an authorized messaging provider such as Sinch ClickSend.
If a Alpha Tag has not been registered by this deadline, messages sent using that alias will be blocked and will not reach recipients.
Registration Process
Applications will be submitted to CNMC by Sinch ClickSend and will require authentication using a valid Spanish digital certificate belonging to the applicant or an authorized representative.
There are two key participants in this process:
The Alias Holder — the company that uses the Sender ID and must be able to demonstrate a legitimate connection to it (check the Proof of ownership section below).
Sinch ClickSend — the messaging provider that delivers the SMS and RCS messages to Spain.
Step 1
Start the process by submitting a registration request through ClickSend. This involves completing the required form: https://clicksend.jotform.com/261091120619045
Answering Key Questions
"Are you registered as a supplier in the Spanish regulator (CNMC) alias registry?"
Select “No” if your company is a standard business, enterprise, or brand registering an alpha tag to send SMS to customers.
Select “Yes” only if your company is an officially registered telecommunications operator/service provider listed in the CNMC registry of telecom suppliers in Spain.
"Are the aliases you want to register already enrolled and active in the CNMC alias registry, showing SINCH COMMUNICATIONS SPAIN S.L. as the registered provider?"
This question asks whether your Sender ID/alias is already registered in the CNMC registry with SINCH COMMUNICATIONS SPAIN S.L. listed as the provider. If you have never registered the alias with CNMC, the appropriate answer is generally “No.”
Providing Alias Owner Information
"Is the alias owner a legal entity or an individual?"
Select whether the alias owner is a Legal Entity (Persona Jurídica) or an Individual/Natural Person (Persona Física).
"Full legal name of alias owner"
Enter the full legal name of the alias owner.
"Tax Identification Number (NIF) of the alias owner"
Provide the Spanish Tax Identification Number (NIF) of the alias owner.
Selecting the Correct Registration Option
Choose “Inscripción de alias” (Alias Registration) when prompted.
Entering the Legal Provider Name
Enter Sinch as the provider. The legal denomination can be specified as “SINCH COMMUNICATIONS SPAIN S.L.” Ensure the name matches exactly how it is registered with the CNMC, as even small differences (e.g., abbreviations, punctuation) can cause the registration to fail.
Step 2
After submission, the Alias Holder will be contacted by the regulator to verify ownership through the CNMC portal.
You will need to:
Sign in to the CNMC portal using your digital certificate
Upload your proof-of-ownership document — Confirmation of the connection type and business purpose of the Sender ID will be requested directly by CNMC. CNMC notifies the alias holder to confirm the connection to the alias and the relationship with Sinch (within 10 business days of notification)
Confirm Sinch as your registered provider — CNMC will send you a notification; you must approve this within 10 business days by logging into the CNMC portal.
Ensure the provider name is entered exactly as “SINCH COMMUNICATIONS SPAIN S.L.” in the CNMC portal to avoid registration errors.
CNMC reviews and validates the submission — up to 1 month normally; up to 3 months during the first 6 months after the Circular enters force (i.e., until September 2026)
Alias is registered and authorized for use
*If the CNMC requires corrections, a 10-day window is granted to provide them; failure to respond may result in the application lapsing
Once approved, the Sender ID will be officially registered and permitted for use with ClickSend.
Best Practices for Successful Registration
Double-check all form fields for accuracy before submission.
Ensure the legal provider name matches CNMC records exactly.
Allow time for both CNMC and ClickSend provisioning processes to complete.
Important Requirements to complete registration
Spanish digital certificate
Your authorized representative will need a valid FNMT-RCM digital certificate to access the CNMC portal. This requires a Spanish DNI, NIE, or EU registration certificate. Non-EU and non Spanish NIE representatives cannot obtain this certificate directly and should consult their legal advisor about appointing an EU-based authorized representative.
Proof of ownership
The CNMC will request proof of Legitimate connection. In simple terms, it means being able to demonstrate that the alias has a direct and reasonable link to the organization requesting it.
This is typically evidenced through verifiable elements such as:
Registered trademark with OEPM (Spanish Patent and Trademark Office) or EUIPO
Registered trade name with OEPM
Corporate legal name registered in the Commercial Registry
Internet domain registered with Red.es or ICANN-accredited registrars
Other public registries (national or international)
Professional use declaration (if none of the above apply — requires a sworn statement plus authenticated contracts or supporting documentation)
The CNMC requires a responsible declaration justifying the connection, but organizations should have supporting documents available in case the CNMC requests additional information.
FAQ's
How long is my Alpha Tag (alias) valid for?
Your registered Alpha Tag will be valid for a maximum of 24 months, however this will be automatically suspended after 12 months if not used.
What happens if my Alpha Tag (alias) expires or is suspended?
The alias holder has 1 month to reactivate a suspended alias; otherwise, it is permanently cancelled and will need to go through the registration process again. There is a 6-month cooling-off period before you will be able to register.
How can we register our Alpha Tag is we do not have a local representative in Spain?
You may proceed by contracting a law firm locally who may be able to assist.
Why is the Spanish Regulator enforcing this?
The regulation's primary goal is to minimize fraud associated with message identity. By controlling and registering these aliases, the CNMC aims to prevent their misuse for impersonation, confusion, or fraudulent activities.
What Sender options do I have if I am not able to register an Alpha Tag?
You can use a local or dedicated number to still send messages to Spain.
Why are SMS messages sent from a random number even after CNMC approval?
CNMC approval does not sync with ClickSend in real time. Until the alias/Sender ID is also approved and provisioned on ClickSend’s side, the network may override the Sender ID and deliver messages from a random number to ensure delivery. Once provisioning is complete on ClickSend’s end, messages will send with the approved alias.