Spain's New 400 Prefix: How to Spot and Block Commercial Calls 2026

Starting today, Spain's new 400 prefix for commercial calls is in effect, a measure designed to help consumers recognize telemarketing calls before answering. The rule, from the Ministry for Digital Transformation, requires companies to use nine-digit numbers beginning with 400 for all commercial calls.

The goal is simple: you know if someone is trying to sell you something before you pick up. But while this is a significant step, it won't completely eliminate spam calls. Here's what you need to know.

What Is the 400 Prefix and Why Does It Matter?

The 400 prefix is a dedicated numbering range for commercial calls. From now on, only numbers starting with 400 can be used for telemarketing. The resolution was published in the Official State Gazette (BOE) in April, and it takes effect today, October 17, 2026.

These numbers are unidirectional: they are only for receiving calls. You cannot call them back, which prevents potential fraud from returning calls to unknown numbers. This is a key security feature.

However, there are nuances. During a customer service call, a company might inform you of an offer, but only if it's related to resolving your query, complaint, or incident and if it improves conditions or price, as per Article 16.2 of Law 10/2025 on Customer Service.

How to Recognize a Commercial Call

Recognizing a commercial call is now straightforward: just look at the number. If it starts with 400, it's a commercial call. This allows you to decide whether to answer or not.

Previously, telemarketers used various numbers, often mobile or landline numbers that looked like personal calls. Now, the 400 prefix clearly identifies them. This transparency is the main benefit for consumers.

But remember, not all calls starting with 400 are necessarily spam. Some could be legitimate offers you might be interested in. The difference is that now you have the choice.

Why the 400 Prefix Won't End All Spam Calls

While the 400 prefix is a strong measure, it won't completely stop spam calls. Here's why:

• Fraudulent calls: Scammers may spoof numbers or use other methods to bypass the prefix, so you still need to be cautious.
• International calls: Telemarketers from outside Spain may not follow the rule, and their numbers won't start with 400.
• Legitimate exceptions: Customer service calls may include offers, so not all non-400 calls are spam.
• Enforcement challenges: Companies that violate the rule may not be caught immediately, so some spam may persist.
• Other channels: Spam can also come via SMS, WhatsApp, or email, which this rule doesn't cover.

So, while the 400 prefix helps, it's not a silver bullet. You still need to stay vigilant.

How to Block Commercial Calls

Even with the 400 prefix, you might want to block commercial calls altogether. Here are some methods:

Use your phone's built-in blocking features: Most smartphones allow you to block specific numbers or enable spam filters. For example, on iOS, you can silence unknown callers; on Android, you can use the spam protection feature.

Register on the Robinson List: In Spain, the Robinson List is a service that helps you stop receiving commercial calls. By registering, you indicate that you don't want to be contacted for marketing purposes. Companies are required to respect this.

Use third-party apps: Apps like Truecaller or Hiya can identify and block spam calls. They use crowdsourced data to flag suspicious numbers.

Contact your operator: Some telecom providers offer call-blocking services for an additional fee or as part of your plan.

What to Watch Next

The effectiveness of the 400 prefix will depend on enforcement and adaptation by companies. Watch for reports of violations and how the Ministry for Digital Transformation responds. Also, keep an eye on whether other countries adopt similar measures, as spam calls are a global issue.

In the meantime, use the tools available to protect yourself. The 400 prefix gives you more control, but your vigilance is still key.

Comparison of Call Blocking Methods

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