The Government once again hits the table when it comes to commercial calls and this Thursday it has taken a decisive step to avoid unwanted contacts or impersonation scams. In this way, starting in October, as the Official State Gazette has already published (BOE) any commercial communication will have to be made from a nine-digit number starting with 400.
The new measure already appears in a resolution of the Secretary of State for Telecommunications and Digital Infrastructure that has been officially published this April 16, in which a period of 6 months is granted for it to be effectively implemented. Once the period ends, operators will have to block commercial calls that do not use the assigned numbering.
As recognized by the Executive through the Ministry for Digital Transformation and the Public Service of Óscar López, this proposal pursues a double objective. On the one hand, a call of a commercial nature is immediately recognized and it is the user who decides whether to pick up the phone or not. And on the other hand, put an end to the use of mobile numbers that confuse the recipient, who may think it is a private call.
The BOE resolution highlights that this number 400 is attributed to “facilitate the identification” of these communications by improving the use of public numbering resources.
Commercial customer service must be identified in a special way
The Law 10/2025 on Customer Service Services approved in December established that customer service and commercial activity by telephone must be differentiated and have special numerical codes. The rule requires the blocking of commercial calls that do not meet these criteria, which must be authorized by the Secretary of State.
This regulatory development also completes a strategy started earlier. The ministerial order approved in February 2025 already prohibited the use of mobile numbering for customer service calls or unsolicited commercial calls, and assigned the 800 and 900 numbers to these services, maintaining their free for whoever returns the call. The Ministry now maintains that the new resolution more precisely delimits which numbering can be used in each case and more clearly separates the commercial call from after-sales assistance or the procedures for existing clients.
Numbers starting with 400 will be unidirectional
There is one element that must be taken into account and that is that numbers starting with 400 are unidirectional, that is, the call cannot be returned. In this way, the risks of fraud associated with a callback when it is to an unknown number are reduced.
The Ministry also recalls that operators may offer their subscribers the possibility of completely disconnecting from the service of commercial calls made through this range, which opens the doors to more serious filtering for those who do not want to receive any.
The distinction between commercial activity and customer service is relevant because it responds to an old complaint from consumers and associations: the interested mix between sales, assistance and complaints. The Customer Service Law already insisted that the channel intended to resolve queries, incidents or complaints must be clearly separated from any other activity of the company. In this logic, numbering ceases to be a technical detail and becomes a transparency tool and the citizen must know, before even picking up, whether they are facing a commercial offer or a legitimate channel of relationship with the company.
Government anti-fraud plan
The Government has begun with this first step, the Anti-Scam Plan for both telephone and SMS, which began in March 2025. According to the information provided by the Ministry in April, the application of these measures would have already blocked more than 169 million calls and 10 million SMS.
Now it remains for the CNMC (Stock Market Technical Commission) to implement the plan to block messages sent with aliases that are already registered. It is also expected to enable a public portal to check which aliases are registered and who is the owner, a measure aimed at stopping smishing, impersonation of banks, companies or administrations.