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400 numbers are the numbering range that Spanish regulations reserve for outbound commercial calls. If your company is required to use them, your agents must call from a 400 number whenever a call has a commercial purpose, such as selling a service, qualifying a lead or booking a meeting.
This page summarizes the regulations to help you set up your numbers. It is not legal advice. If you are unsure whether your company or a specific campaign is affected, check with your legal advisor.

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What you need to know

  • Outbound calls only. Nobody can call a 400 number, not even to call you back.
  • Not for customer service. Don’t use them for support, incidents or complaints.
  • Same price as any other number: €1.95 + VAT per month.
  • No province invoice needed for identity verification.

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What the regulations say

The Spanish Customer Service Act (Ley 10/2025) requires the companies within its scope to use separate numbering for customer service and for commercial calls. The Resolution of 14 April 2026 reserves 400 numbers for outbound commercial calls and gave companies six months to adapt. Since 17 October 2026, affected companies must make their commercial calls from a 400 number.

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Which companies are affected

The obligation to use a 400 number applies to companies within the scope of Ley 10/2025:
  • Companies providing basic services of general interest: water, gas, electricity, passenger transport, postal services, electronic communications and financial services.
  • Companies that mainly serve consumers and that, alone or as a group, reached at least one of these thresholds in the previous financial year: 250 employees, €50 million in annual turnover or €43 million on the balance sheet.
If your company is not within that scope, you don’t have to use a 400 number. Your commercial calls must still comply with article 66 of the General Telecommunications Act and the AEPD Circular 1/2023 on unwanted commercial calls.
A 400 number identifies the call as commercial, but it does not replace consent, the right to object or the data protection obligations that apply to your campaign.

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When to use a 400 number

What counts is the real purpose of the call: the script, the reason for calling and what you want the person to do. Calling a campaign a “follow-up” or a “reminder” doesn’t make it non-commercial. If a call starts as customer service or a notice and is used to offer or sell something, it becomes commercial.

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Calls made by AI agents

Using an AI agent doesn’t make a call commercial: the purpose decides, just as with a person. An agent that calls to sell, qualify a lead or book a meeting must use a 400 number. An agent that confirms appointments or answers inbound calls doesn’t. Also keep in mind that:
  • Article 50 of the EU AI Act may require you to tell the person that they are talking to an AI system.
  • Article 66.1.a of the General Telecommunications Act may require prior consent for commercial calls made without human intervention.

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Buy a 400 number

1

Choose the Commercial (400) prefix

Go to Phone Numbers and click “Buy number”. Under Prefix, choose Commercial (400) and select the numbers you need.
2

Complete payment

You will be redirected to Stripe to pay securely.
3

Verify your identity (if your project is not verified)

If your project is already verified, the numbers are activated when you complete the payment. Otherwise, upload only the signed verification document: 400 numbers don’t need a province invoice. See the verification process.

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Use a 400 number in your calls

A 400 number can’t have an inbound agent: the number’s settings show it as not available, and when you publish an agent you can’t pick it as an incoming number. To make your commercial calls from the 400 number, use it as the caller number:
  • In a flow: choose it under From number in the Make Call action.
  • Through the API: pass it as from_number when you create a call.
Before you launch a campaign, place a test call and check that the person you call sees the 400 number.
Since nobody can call you back on a 400 number, offer another way to reach you: a geographic number with an inbound agent, an email address or a booking link. You can add it to your agent’s prompt so it shares it during the call.

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Geographic numbers

Geographic numbers are still valid for receiving calls, for customer service and as a callback channel. If your company is required to use a 400 number, don’t use them as the caller number for commercial calls: the carrier may block commercial traffic it detects from geographic numbers.

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FAQ

No. 400 numbers only make outbound calls. Use a geographic number to receive calls.
No. The change only affects commercial calls made by companies within the scope of Ley 10/2025. Your geographic numbers still work for receiving calls and for calls that are not commercial.
No. It depends on the purpose of the call, not on whether an AI agent makes it. See When to use a 400 number.

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Regulations

All of these are published in Spanish, except the EU AI Act.