Telemarketing calls must use the 400 prefix from October in Spain

Spain's Ministry for Digital Transformation has approved an order, published in the BOE (official state gazette), requiring every commercial call to come from a number with the 400 prefix and setting October 2026 as the deadline for operators to block the rest. The new numbers will be one-way: calls can be received, but not returned.

The war against the phone that rings in the middle of the afternoon now has a date. The Ministry for Digital Transformation, headed by **Óscar López**, has published in the BOE an instruction that changes the rules of the game: from **October 2026**, any commercial phone communication will have to come from a number starting with **400**. If it doesn't carry that prefix, the operator cuts it off before it reaches anyone's mobile.

The measure is part of the Anti-Scam Plan and goes beyond a mere change of numbering. The minister explained it at an event held by **AMETIC**, the technology industry association: "All citizens should know that from October they will only be able to receive commercial calls coming from a 400 number, and everything else will be blocked."

## A number you can't call back

The new 400 numbers have a particularity that matters more than it seems: they are one-way. The citizen receives the call, but the system prevents them from calling back. With this, the Government wants to disable callback scams, the trick where a fraudster leaves a missed call so the victim rings back a premium-rate number and runs up a hefty bill.

Operators will also have to offer their customers the option of completely restricting any commercial contact linked to those 400 numbers. In other words, anyone who doesn't want a single advertising call, even with the correct prefix, can shut the door entirely.

## SMS will also have to be registered

The package doesn't stop at voice calls. The **CNMC** (Spain's telecom regulator) will create an official register in which companies and organisations must list the alphanumeric codes they use as SMS senders. From **7 June**, operators will block any message whose sender does not appear in that verified database. "From June, no more SMS impersonating companies," said López, who summed up the goal: "Only companies and entities listed in that CNMC register will be able to send those mass messages."

These measures add to an earlier protocol that, since **March 2025**, bans the use of mobile numbers for customer service and requires short numbers, local landlines or free ranges such as **800** and **900**.

## 192 million calls blocked

The minister argued that the measures already in place are delivering results: "With the measures we have implemented so far, we have already blocked **192 million calls** and **17 million SMS**." According to industry figures, companies such as **Telefónica** currently intercept around **500,000 fraudulent calls every day** before they reach the user's handset.

The rule will apply to all companies, with one exception: small electricity, gas and telephone operators with less than a **5% market share**, fewer than **250 employees** or annual revenue below **50 million euros**. If any of them breaches the rule once it takes effect, citizens can complain to the **Oficina de Atención al Usuario de Telecomunicaciones (OAUT)** (telecom consumer complaints office) or to the CNMC.

It is worth remembering that no rule eliminates the risk of fraud: if a call or message asks for bank details, passwords or urgent payments, the sensible thing is to be suspicious and verify through an official channel.