Spain Sender ID guidelines

Alphanumeric Sender ID

Supported

Registration requirements

KYC+
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Spain's national telecommunications regulator, the Comisión Nacional de los Mercados y la Competencia (CNMC), has established a mandatory Alias Registry. All alphanumeric Sender IDs used to send SMS messages to Spanish recipients must be registered in this registry before use. Unregistered Sender IDs are subject to blocking by Spanish mobile operators.

Voxbone SA (now part of Bandwidth Inc.) is registered in the CNMC Alias Registry as an originating provider. Infobip is Bandwidth's designated local partner for Spain and will act as the authorised third party to submit alias registrations on yours and our behalf through the CNMC portal.
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Please follow the steps below in order to have your Sender ID registered:
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Step 1 — Submit a Registration Request to Bandwidth

Contact Bandwidth's Messaging Registration Support Team to initiate the process. You will need to provide the following information about the brand owner (alias holder):

Step 2 — Bandwidth Submits the Application to the CNMC

Once Bandwidth receives your information, we will complete the inscription form on the CNMC's electronic registry portal, identifying the brand owner as the alias holder and selecting Voxbone SA as the originating provider. The application will enter "pending authorisation" status.
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Step 3 — Brand Owner Approval (Mandatory — 10 Working Day Deadline)

Upon submission, the CNMC will send an electronic notification to the legal representative of the brand owner. The legal representative must then:

Important: Silence within the 10-working-day window is treated as non-authorisation. If the legal representative does not act in time, the application will be automatically deemed not made and the alias will not be registered. A new submission will be required.
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Step 4 — Registration Confirmed

Once the brand owner approves, Voxbone SA will be enabled as the originating provider for the alias. Bandwidth will notify you once the alias is fully registered and provisioned on your account, and messaging traffic may commence.
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Digital Certificate Requirements

Access to the CNMC's Sede Electrónica requires a valid @firma-compatible digital certificate. This applies to the brand owner's legal representative when approving the alias registration.

Frequently Asked Questions
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What is the CNMC Alias Registry?
The CNMC Alias Registry is Spain's mandatory national registry for alphanumeric SMS Sender IDs, established under Circular 1/2026. All aliases used to send SMS to Spanish recipients must be registered in this registry. Unregistered aliases may be blocked by Spanish mobile operators.
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Who is Voxbone SA?
Voxbone SA is part of Bandwidth Inc. group of companies and is registered in the CNMC Alias Registry as an originating provider. Voxbone SA will be designated as the originating provider for your alias in the registry.
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What does "alias holder" mean?
The alias holder is the brand owner — the company that owns the brand, product, or service associated with the Sender ID. The alias holder is responsible for approving the registration through the CNMC portal.
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What happens if the brand owner misses the 10-working-day approval window?
If the brand owner's legal representative does not log in to the CNMC portal and expressly approve the application within 10 working days of receiving the CNMC notification, the application is automatically deemed not made. The alias will not be registered and a new submission will be required from the beginning.
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Are international (non-Spanish) brands eligible to register?
Yes. International brands are eligible. They can access the CNMC portal using an Electronic Identity (EID) certificate, or by engaging a local Spanish legal firm to manage portal access on their behalf.
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What is the Annex V declaration and who needs to sign it?
The Annex V is a legally required declaration confirming the brand owner's legitimate link to the alias (e.g. a registered trade mark or trade name). It must be electronically signed by the brand owner's legal representative at the point of approving the registration in the CNMC portal. There are two versions: Annex V.a (with an official register link) and Annex V.b (without one).
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What should I do if I receive an email or notification from the CNMC?
These notifications are part of the official registration workflow. The brand owner's legal representative must follow the instructions to log in to the CNMC's Sede Electrónica and approve the application within 10 working days. Please contact Bandwidth's Messaging Registration Support Team if you have any questions.
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How do I check my Sender ID registration status?
You will receive a confirmation from Bandwidth once your alias is approved and provisioned on your account.
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What should I do if the alias is stuck in a Pending status?
Please check whether the brand owner's legal representative has received and acted on the CNMC notification. If the 10-working-day window has not yet passed, the representative should log in to the CNMC's Sede Electrónica and approve the application. If you are unable to resolve the issue, please contact Bandwidth's Messaging Registration Support Team.
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Is registration free?
Registration in the CNMC Alias Registry is currently free of charge.

Country regulations

General consent requirements.

Content restrictions

Phishing, other scams, and gambling content is strictly prohibited.

Additional information

For the full list of supported networks in Spain, see our Global Messaging Carrier Reach Matrix.

Note: Due to the rapidly evolving nature of global messaging regulations, this information is subject to change without notice. If you have additional questions, please contact our Messaging Registration Support Team.