What's changing?

Spain's national telecom regulator, the CNMC (Comisión Nacional de los Mercados y la Competencia), now requires an RCS Sender to be registered in a national Alias Registry.

Starting September 15, 2026, messages sent using unregistered RCS Sender will be blocked.

Key terms

Before diving in, here are some terms you'll see throughout this process:

Required Information to Register your Sender ID

Regardless of your registration path, you'll need to provide:

Sender Information:

• The sender ID (alias) you want to register
• How the sender ID connects to your business (legitimate linkage type)

Business Information:

• Business type: Individual (PF) or company (PJ). 
• Tax identification number (NIF for Spanish entities, EU VAT ID, or equivalent)
• Registered business name

Legal Representative Information:

• Full name (first name, surname)
• ID number (NIF, passport, or equivalent)
• Email address (this is where CNMC sends verification notifications)

Third Party (Tercero) Information:

• If an entity other than your company and Twilio is involved in managing or sending messages with your sender ID (e.g., a marketing platform or agency), their details are required.

Twilio Supported Registration Paths

Twilio supports two ways to get your sender ID registered with the CNMC:

RCS Sender Format Requirements

Your sender ID must comply with these CNMC specifications:

• Length: 3–40 characters
• Allowed characters: Letters (a–z, A–Z, including ñ and ç), numbers (0–9), and special characters: @ & - _ . + and spaces

Prohibited:

• Purely numeric sender IDs
• Generic terms that don't identify a specific business (e.g., "Message", "Bank", "Alert")
• Leading or trailing spaces
• Consecutive spaces
• Accented vowels (á, é, í, ó, ú)
• Offensive or misleading content

How to choose your path

Choose Self Registration if:

• You already have a Spanish FNMT digital certificate
• You want direct control over your CNMC submission
• You want fastest path to register

Choose Twilio as Authorized Representative if:

• You don't have and can't easily obtain a qualifying digital certificate
• You're a company outside Spain/EU without local representation

Path #1: Self-Register your RCS Sender with CNMC 

1. Go to the CNMC Alias Registry portal
   Visit https://tramites.cnmc.gob.es/formulario/213/ and authenticate with your digital certificate.
2. Complete the Alias Registration Form
   Fill in your company details, legal representative information, and the sender ID you want to register. When completing the form:

• Select Twilio Ireland Limited as your PRO (Provider)
• If an ISV or other platform sends traffic on your behalf using this sender ID, list them as a Third Party (TERCERO)

Important: You must choose “Twilio Ireland Limited” as the PRO in order for traffic to be delivered by Twilio. 

3. Your Legal Rep Authorizes the Registration 
   The CNMC will send an email to your legal representative. The representative must log into the portal with their digital certificate and approve the registration within 10 business days. If you miss this window, your registration is rejected and you'll need to resubmit.
4. Share your proof of registration with Twilio
   Once the CNMC has approved your application, share the “justificante” document you received during the application process with Twilio. This document is used to validate your registration. 

Path #2: Twilio as Auth Rep 

Only companies outside of Spain can use this registration flow. 

Here's the end-to-end process for Twilio as Auth Rep:

1. Confirm Eligibility 
   Only non Spanish entities can utilize the Twilio as Auth Rep flow. If you are an ISV and need to register your end user, you will need to first sign a supplemental agreement with Twilio prior to registering. Please contact your account executive to receive the agreement. 
2. Submit your onboarding request to Twilio Operations
   Send an email to messaging-channels-rbm@twilio.com using the exact subject line:

“[Your RCS Agent Name] Spain RCS Twilio as Auth Rep Manual Onboarding”

Your email must include the following documentation:

• Proof of Business: Business document showing legal name, address, registration number, and officers of company
• CNMC Letter of Authorization for Foreign Entities: The CNMC LoA must be signed by the legal representative of the Sender ID holder
• Proof of Sender Link: Proof that the business has the right to use the specific Sender ID requested if the sender ID is not the business name. 

3. Verify Authorized Representative
   The application must be verified by a legal representative of the business. Following the submission of your application, Twilio will send you a secure link to collect the government ID to be completed by a business officer. This officer must be listed in the business registration documents. 
4. CNMC Review
   Once all documents have been collected and reviewed by Twilio you application will be submitted to the CNMC for approval by Twilio.
5. Alias Registered with the CNMC
   On approval, the Alias will be registered with the CNMC and is eligible to be used for an RCS Sender. 

Frequently Asked Questions

Do I need to register each sender ID separately?

Yes. Each unique alias requires its own registration with the CNMC. Each RCS Sender is case sensitive. 

What happens if I don't register before September 15, 2026?

Your messages using unregistered RCS sender IDs will be blocked. We recommend setting up an RCS fallback so your messages can be delivered. 

I'm an ISV with many customers using RCS sender IDs. What should I do?

Each sender ID used by your customers must be registered. All of your customers with digital certificates should Self Register and list you as the Third Party. Be sure to share your exact company name and Tax ID with the customer as an exact match is required for traffic to not be blocked. Once your customer has registered, submit this information to Twilio. 

How much does registration cost?

Registration with the CNMC is free. 

I don't have a Spanish digital certificate. What are my options?

You can either: (1) appoint a representative who holds a valid digital certificate to submit on your behalf, or (2) use Twilio as the authorized representative.