Spain's 400 prefix curbs legal spam but not phone scams

The 400 prefix stops legal spam, not phone scams

The first call of the post-400 era came from a number starting with 400. On the other end, a female voice that, upon hearing a serious tone, simply hung up. The anti-nuisance filter came into force on 19 October 2026 and phones began blocking sales calls by default, but the result six days later is a mixed picture: fewer unsolicited offers and the same army of scam attempts, now disguised with area codes from all over Spain.

The starting point is summed up by an everyday scene: the handset stops ringing for the textbook call center, but keeps buzzing with the familiar Madrid 91 and the brand-new 400. The rule does not distinguish between those who call to sell and those who call to steal, and that is where the problem begins. Some operators have gone for the scissors: O2 has blocked all 400 numbers, according to one customer's account. The downside is obvious: if the company calls about a line issue or the supplier warns of an outage, the message disappears into limbo.

What the 400 prefix changes, and what it doesn't

The 400 prefix was created as territory for "legal" spam, the kind from companies that until now roamed freely on the basis of presumed consent. That is the flank the measure strikes. The other one, the pirate call center and the gang posing as your bank by spoofing private numbers, laughs at the block: scammers don't care about the prefix because they change it whenever they want. The practical consequence is that people who blindly block the 400 lose the legitimate calls and keep receiving the illegitimate ones.

The available evidence points to migration, not extinction. The Madrid numbers that have been a nuisance for more than two years are still active. And the 400, far from disappearing, has started showing up with Spain's country code, 34, in front of it, like someone putting on a new mask. The filter learns; so does the spammer.

The problem with the calls that do matter

There is an invisible group in this whole story: those who need to receive calls to work. For them, mass blocking is shooting themselves in the foot. A pending request with a provider, a breakdown alert, an appointment confirmation: all of that travels through the same channel as fraud and doesn't always carry an identifiable sender. The dilemma is uncomfortable: either answer everything and put up with the scams, or filter everything and miss the urgent.

The alternative some have adopted is the unknown-number policy: if there's no identification of who's calling, the phone doesn't get picked up. It works as a low-tech filter, though it rules out any communication that doesn't come labeled. And it doesn't solve the underlying problem, which is that the system allows a private individual to receive a call from a number that isn't the one actually dialing.

The verdict after the first week

The diagnosis that imposes itself is one of partial pogre with an expiration date. The 400 numbers blocked by default do reduce commercial noise, yes. But phone spam wasn't just a nuisance: it was a business with two legs, the legal one and the incivil one, and the rule has only cut off one. The other keeps operating with total impunity, adapting its disguise.

The question remains of who is behind the measure. Some argue that the Saunez government wouldn't have produced anything good of its own accord and point to Brussels as the origin of the directive. If the impetus came from the EU, the local credit is rather scarce. And if this is the result, there isn't much to celebrate either: the phone keeps ringing, only now the caller has learned to look like something else.