Spain now makes telemarketers call from 400 numbers. Here is what that does and does not stop

Spain has given sales calls a label. Since Saturday, October 17, 2026, utilities, telecom carriers, transport and financial companies, plus any large business selling to consumers, may only place telemarketing calls from nine-digit numbers that begin with 400. A Spanish phone showing a 400 number is therefore a sales pitch, and the person holding it can decide not to answer. Carriers may also offer to cut off the whole range, though they are not required to, and neither Android nor iOS can block a prefix out of the box. OCU, Spain's largest consumer organization, welcomes the rule but says a 400 number still does not reveal who is calling or whether you ever agreed to it.

The requirement comes from a resolution by Spain's telecom authority published in the official gazette on April 16, which implements the country's new customer service law. Carriers and companies had six months to prepare, and that window closed on October 17.

A 400 number can call you, but you cannot call it

The range is outbound only. Carriers are barred from connecting any call made to a 400 number, so a missed call cannot be returned. The government says this targets a familiar scam in which a missed call lures people into ringing back an unknown line.

Customer service is kept separate. When a bank or power company calls about an outage or a complaint, it has to use a short code, a toll-free 800 or 900 number, or a regular landline, according to the government announcement that accompanied the two resolutions. Those numbers work in both directions, so blocking 400 should not silence service calls from companies you already deal with.

What the prefix does not show is a name. Nine digits will not tell you whether the caller is your carrier, an energy retailer or an outsourced call center working on its behalf, and the resolution does not require that identity to be displayed.

Blocking 400 calls through the carrier or the phone

The only way to cover the entire range is through the carrier. The resolution allows Spanish operators to switch off incoming 400 sales calls when a customer asks, but it is an option rather than a right, so availability and price vary. Where it is offered, it must take effect within ten working days, according to an analysis by law firm Gómez-Acebo & Pombo.

Some carriers already run their own filters. Movistar and O2 let customers block calls their network flags as spam at no cost, through the Mi Movistar app or by calling 1551 on O2, Xataka Móvil reported. That filter relies on lists of suspicious numbers, and there is no documentation saying it stops every 400 call.

iPhones cannot block a prefix either. Apple's support page describes a Screen Unknown Callers setting under Settings > Apps > Phone. Silence sends calls from numbers that are not in Contacts straight to voicemail, while Ask Reason for Calling has the iPhone question the caller before it rings. A separate Spam toggle under Call Filtering sets aside calls the system suspects. The catch is that a courier or a doctor's office you have not saved gets filtered too.

On Android, it depends on the dialer. In Phone by Google, used on Pixels and many other handsets, go to More options > Settings > Caller ID & spam and turn on Filter spam calls, as Google's help page explains. Flagged calls do not ring but stay in your call history. Samsung's dialer has a Block unknown numbers switch, and both apps let you block an individual number from the call log.

Neither lists a prefix block among its documented settings. Some third-party apps offer one, but they usually ask for access to your contacts and call history, so check what they share before installing. Blocking numbers one at a time does little against telemarketing, since a company can rotate through hundreds of lines.

Sales calls that will still arrive without a 400

Not every business is covered. Under article 2 of Law 10/2025, the rule applies to essential services (water, electricity, gas, transport, postal, telecom and finance) and to consumer-facing companies with at least 250 employees, annual revenue above 50 million euros or a balance sheet above 43 million euros. Electricity, gas and phone retailers with less than 5% of the national market are exempt unless they are large companies. A language school or a small shop can keep calling from an ordinary landline.

Mobile numbers are off-limits to everyone. A ministerial order, TDF/149/2025, has banned sales calls from mobile numbers since June 7, 2025, so a salesperson calling from a Spanish number starting with 6 or 7 was already breaking the rules.

Scammers will not use a 400 number either. The same order requires carriers to block calls showing unassigned Spanish numbers and international calls disguised with a Spanish number when the caller is not roaming. A call that genuinely comes from abroad on a foreign number sits outside Spanish law, and Xataka Móvil reports that some of the fraud has moved there.

If a covered company tries to sell you something from another number, the government says you can report it to the telecom user office (OAUT) or to the CNMC, the competition and markets regulator. Law 10/2025 treats violations as consumer infringements, but neither the law nor the resolution sets a specific fine for this conduct. The law also allows carriers to block lines that make sales calls without the code, although their detection systems first need express approval from the telecom authority.

Why OCU says the prefix is not enough

An OCU survey published in May found that 98% of Spanish consumers were still getting unsolicited sales calls, and the share receiving more than ten a month had risen from 37% to 58% in a year.

In an October 15 analysis, the group argues that the prefix flags a sales call without making it easy to find out which company is behind it or whether you ever gave consent. It wants a public registry where people can check that consent, clear and dissuasive penalties for calls made without permission or without the prefix, and a simple, free way to exercise data rights. OCU adds that 400 does nothing about scams, fraud from abroad or caller ID spoofing, and warns that consumers cannot let their guard down.

Other steps for people in Spain

Sign up for the Lista Robinson, a free opt-out registry run by the digital industry group Adigital that removes your number from marketing by companies you have not authorized. It can take up to two months to work and does not stop firms that already have your consent. Only 18% of OCU's respondents had registered.

If the caller is a company you have a contract with, ask it in writing to stop sales calls and note the dates and type of call, as OCU recommends. The organization also points out that a contract signed during a sales call you did not agree to is considered invalid.

And if anyone asks for a code sent by text message or for card details, hang up, whatever the prefix. That code is often the key to an account, as our guide to protecting and recovering Steam, PSN and Xbox accounts explains. A caller who knows your name or your provider is not proven genuine either. Leaning on familiar details is the same trick behind the fake GTA 6 preorders and downloads built to look legitimate.