The Directorate of Telecommunications and Audiovisual of the National Markets and Competition Commission (CNMC) of Spain has introduced a mandatory Sender ID Registry (Registro de Alias) under Order TDF/149/2025.
This regulation applies to all companies, both Spanish and international, that use alphanumeric Sender IDs to send SMS or RCS messages to Spanish mobile numbers. Beginning September 15, 2026, Spanish mobile operators will be legally required to block any SMS, MMS, or RCS message sent using an alphanumeric Sender ID that is not registered in the CNMC Sender ID Registry. Any traffic sent using an unregistered Sender ID after this date will not be delivered. Numeric Sender IDs are not affected by this requirement.
Registration with the CNMC is free of charge. Organizations that have access to a Spanish digital certificate can register their Sender IDs directly through the CNMC Sender ID Registry Portal. Organizations without a Spanish digital certificate can authorize Telesign Corporation to complete the registration on their behalf by providing a signed Letter of Authorization (LOA) together with the required registration information.
Reseller customers should be aware that each Sender ID must be registered by its respective owner, and Telesign can only submit registrations for organizations that have provided a Letter of Authorization directly to Telesign. A chain of Letters of Authorization is not permitted under the CNMC registration process.
✅ Action Required
If you use alphanumeric Sender IDs to send SMS or RCS traffic to Spanish mobile numbers, please ensure that your Sender IDs are registered with the CNMC before September 15, 2026. We encourage you to begin the registration process as soon as possible to allow sufficient time for completion before the enforcement date and to avoid potential service disruptions.
Please also refer to Telesign's full guidance for scenario-based registration requirements, including detailed registration instructions, required documentation, Letter of Authorization (LOA) templates, and reseller-specific guidance: https://support.telesign.com/s/article/spain---messaging-regulations.
For any questions or assistance, please contact your Customer Success Manager or reach out to enablement@telesign.com.
Thank you for your prompt attention to this important regulatory requirement.
Posted Aug 06, 2026 - 04:40 PDT
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