Summary

  • Spain's new 400 range identifies commercial calls by covered companies. It does not certify who is calling or whether the recipient agreed to be contacted.
  • The numbers are outgoing-only. Behind that simple rule lies a disagreement over how many numbers operators need and what should happen when a number acquires a poor reputation.

A missed call from a Spanish 400 number offers one fewer choice than an ordinary missed call: you cannot ring it back. The restriction is deliberate. These nine-digit numbers are reserved for outgoing commercial calls, not for conversations that a customer starts.

From 17 October, companies covered by the new rule must use the range for their sales calls. The aim is to give the person holding the phone useful information before they answer. The first three digits disclose the purpose of the interruption. They do not tell the whole story of the caller.

That visibility is also what worried one operator during the preparations. In submissions recorded in the CNMC's July allocation decision, MasOrange argued that making commercial calls so recognisable could increase rejection, reports and filtering. It sought numbering capacity that would also allow numbers affected by reputational deterioration or functional problems to be replaced.

CNMC did not accept those problems as grounds for additional numbers. A lower chance of getting through, it reasoned, was not a sufficient justification for issuing more numbering resources. The exchange captures the tension more clearly than the launch slogan: a label meant to help people decide not to answer is unlikely to delight everyone trying to reach them.

No return journey

The final 400 resolution requires operators to enable calls from the range while prohibiting calls to it. It also bars its use for customer service. A business cannot turn its new sales number into the number customers must call for help.

This was a choice, not an inevitable property of a prefix. In its April consultation response, CNMC had proposed making return calls free. The adopted rule instead removed the return path. Readers encountering older discussion of free callbacks therefore need to distinguish the proposal from the rule that took effect.

Customer care has a separate set of numbers: specifically assigned short codes, free 800 and 900 numbers, or geographic numbers under the companion resolution. Geographic numbers are not necessarily free. The separation makes the commercial caller's job more legible, but it leaves the company responsible for maintaining a different way to reach support.

Nor is 400 a badge of trust. The rule assigns a purpose to the number; it does not establish the truth of a sales claim, prove the caller's identity or supply the recipient's consent. Recognising an offer and being entitled to make it remain different questions.

A number is not a disposable disguise

Before launch, 47 operators initially requested 354 blocks of 1,000 numbers. The July decision's final allocation table assigned 98 blocks, including later applications. The figures describe demand and allocation, not calls made or people reached.

To distribute the first numbers, CNMC used operators' effective use of 800 and 900 numbering in 2025 as a reference. Some operators disputed how well that history represented the new demand. CNMC's answer was not that future needs could never grow: further applications remained possible when supported by efficient use. It resisted handing out large stocks in advance.

The MasOrange submission added another question. Should more numbers be available because existing ones become less likely to be answered? CNMC treated numerous numbers for the same client as inefficient use, rather than accepting reputational deterioration as a reason to expand the supply. These were arguments made during allocation—not findings that a particular company had abused the new range or that consumers had already rejected it at a measured rate.

The result ties a commercial inconvenience to a public-resource decision. A number that people recognise may be less attractive to a caller, but that alone does not earn the caller a replacement.

The work the prefix cannot do

The obligation applies within the scope of Spain's customer-service law, including specified basic services and qualifying large consumer businesses, with express exceptions. It should not be read as an identical obligation on every business, regardless of size and activity.

There is a further detail for recipients: the resolution says operators may offer disconnection from the 400 commercial-call service on request. That wording does not establish that every operator already offers an automatic, universal switch.

Detecting sales calls that avoid the designated range is harder than recognising three digits. The law provides for objective, reasonable technical systems authorised by Secretaría de Estado de Telecomunicaciones e Infraestructuras Digitales, or SETID. A very high volume of calls may be relevant, as the government's launch notice explains. Volume is still a pattern to assess, not a verdict on each conversation.

The rules and allocation decision establish what was designed and required. They do not, by themselves, measure how well the system has worked since launch. That distinction matters to the next assessment: fewer unwanted calls reaching people, and legitimate calls not being wrongly blocked, would tell more than a large allocation table. For now, the most concrete change is on the screen. A sales call is supposed to announce what it is before asking for someone's time.

Updated 26 October 2026: this edition clarifies the law's scope and the optional wording on operator-provided disconnection, and replaces the launch-notice link. The original URL and publication date are unchanged.