Spain Sender ID (Alias) Registration for SMS, and RCS

Overview

Starting June 7, 2026, all alphanumeric Sender IDs (aliases) must be pre-registered in the official Alias Registry managed by the Spanish Regulator (CNMC, Spain's National Commission for Markets and Competition), and their use must be authorized through a registered provider such as Vonage.

This new regulation applies both for SMS, and RCS messages.

If a Sender ID (Alias) is not registered by June 7, 2026, messages sent with that Sender ID will be blocked and will not be delivered to recipients.

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.

Sender ID (ALIAS) & Format Requirements

An alias is the alphanumeric name (e.g., a brand or company name) that appears to recipients at the top of an SMS or RCS message in place of a phone number. This visible identity is vital for establishing trust and ensuring brand recognition.

SMS

RCS

Registration Process

The registration is submitted through the CNMC's electronic portal and requires authentication with a valid Spanish digital certificate from the applicant or their authorized representative.

Two main parties are involved:

• 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).
• Vonage (Authorized PRO) — the messaging provider that delivers the SMS and RCS messages to Spain.

The registration can be submitted either by the alias holder directly, or by Vonage on behalf of the holder. When Vonage manages the registration, the CNMC will contact the holder to expressly confirm the authorization.

As a result of the registration process, traffic from a registered SID will be allowed only if received from its Authorized PRO (Vonage in this case). Traffic from non-registered SIDs will be blocked.

Phase 1: 

Submit the registration request (via CNMC portal or through Vonage).

Information Required for Registration

This information is requested in the different forms provided above.

Phase 2 (May, 2026)

Once your Phase 1 is submitted, the Alias Holder will be contacted by the regulator to provide proof of ownership via the regulator’s web portal (May, 2026)

1. Log in to the CNMC portal with your digital certificate.
2. 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 Vonage (within 10 business days of notification)
3. Confirm Vonage as your registered provider — CNMC will send you a notification; you must approve this within 10 business days by logging into the CNMC portal. 
4. 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)
5. If the CNMC requires corrections, a 10-day window is granted to provide them; failure to respond may result in the application lapsing
6. Alias is registered and authorized for use

Important Requirements to complete Phase 2

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.

Sender ID (Alias) Life Cycle and Maintenance

• Maximum Term: An alias's validity is limited to a maximum of 24 months.
• Auto-Suspension: The alias is automatically suspended after 12 months of non-use or if it reaches its defined end-of-use date.
• Reactivation Window: The alias holder has 1 month to reactivate a suspended alias; otherwise, it is permanently cancelled.
• Cooling-Off Period: A cancelled alias cannot be re-registered for 6 months.

Need Help?

If you have questions about the registration process or need assistance, please contact your Account Manager or reach out to our Support Team.