Spain

Overview

Starting June 7, 2026, all alphanumeric Sender IDs (aliases) must be pre-registered in the official registry managed by the CNMC, and their use must be authorized through a registered provider such as Closum.

To register your Sender ID, please complete the form via this link.

This regulation applies to SMS, MMS, and RCS messages.

The main goal of this regulation is to reduce fraud related to message identity, preventing impersonation and misuse of Sender IDs.

👉 If a Sender ID is not registered by this date, messages sent using that alias will be blocked and not delivered.

Sender ID (Alias) and Format Requirements

A Sender ID (alias) is the alphanumeric name (for example, a brand name) that appears to recipients instead of a phone number.

SMS/MMS

Rule	Requirement
Length	Minimum 3 characters, maximum 11
Allowed characters	Letters (a–z, A–Z including ñ, ç) · Numbers (0–9) · Spaces (not consecutive, not at start/end) · Special: @ & - _ . +
Not allowed	Numeric-only · Generic names (e.g., "Message", "Bank", "Flight", "Urgent", "INFO", "SMS") · Offensive language · Impersonation · Consecutive spaces · Accented characters (á, é, í, ó, ú) · Symbols: ¡ ! # % ( ) * , / : ; < > = ? [ ] €
Case sensitive	Yes

RCS

Rule	Requirement
Length	Minimum 3 characters, maximum 40
Connection	Must clearly relate to a registered trademark, trade name, company name, or domain
Not allowed	Same restrictions as SMS/MMS
Case sensitive	Yes

Registration Process

Registration is submitted through the CNMC electronic portal and requires authentication with a valid Spanish digital certificate.

Two main parties are involved:

Alias Holder — the company using the Sender ID, which must demonstrate a legitimate connection
Closum (Authorized Provider) — the platform responsible for delivering SMS and RCS messages in Spain

Registration can be submitted:

Directly by the alias holder
Or by Closum on behalf of the customer

👉 If Closum manages the registration, the CNMC will contact the holder to confirm authorization.

After registration:

Traffic will only be allowed through the authorized provider
Non-registered Sender IDs will be blocked

Phase 1 (April 2026)

Submit the registration request (via CNMC portal or with support from Closum).

For bulk submissions, required information should be provided by April 20, 2026.

Single submissions after this date should be made via the CNMC portal or through Closum.

Information Required for Registration

Field	Details	Required
Sender ID / Alias	3–11 chars (SMS/MMS) or 3–40 chars (RCS)	✅
Type of connection	Relationship to the brand (trademark, domain, etc.)	✅
Provider	Closum	✅
Holder type	Individual or Company	✅
Tax ID	NIF/NIE/Passport or CIF/NIF	✅
Holder name	Individual or legal company name	✅
Representative details	Name, tax ID, email, phone	✅
Activation date	DD/MM/YYYY	Optional
End date	Max 24 months	Optional

Phase 2 (May 2026)

After submission, the alias holder will be contacted by the CNMC to:

Access the portal using a digital certificate
Submit proof of ownership/connection
Confirm Closum as the authorized provider

⏱️ Timelines:

Up to 10 business days to respond
Approval timeframe:
- ~1 month (standard)
- Up to 3 months (initial phase until September 2026)

If corrections are required:

A 10-day window is granted
Failure to respond may result in the application being cancelled

Important Requirements to Complete Phase 2

Spanish digital certificate

A valid Spanish digital certificate is required (e.g., FNMT).

If not available:

An EU-based authorized representative must be appointed

Proof of ownership

The CNMC will require proof of a legitimate connection to the alias.

Examples include:

Registered trademark (OEPM or EUIPO)
Registered trade name
Legal company name
Internet domain
Public registries

If none apply:

A professional use declaration supported by documentation may be used

Sender ID (Alias) Lifecycle and Maintenance

Maximum validity: 24 months
Auto-suspension: after 12 months of inactivity
Reactivation window: 1 month
Permanent cancellation: after that period
Re-registration: only possible after 6 months

Need Help?

If you have questions or need assistance, please contact your Account Manager or reach out to the Closum support team.

Updated on: 23/04/2026

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