New Rules for Commercial Calls: The ‘400’ Prefix Becomes Mandatory
According to an announcement from the Ministry for Digital Transformation and Public Function (Ministerio para la Transformación Digital y de la Función Pública), a new regulation aimed at standardizing commercial communications will take effect on October 17, 2024. The core of this regulation requires all commercial marketing calls initiated by companies to be made using a nine-digit number prefixed with ‘400’.
The legislative goal is to empower consumers with clear identification. When a user receives a call starting with ‘400’, they can immediately recognize its commercial nature and decide whether to answer. Telecom operators will be required to block any commercial communications that do not use this designated prefix, reducing harassment and potential scam calls at the source.
Crackdown on SMS Scams: Strengthening Sender Verification
In addition to telephone measures, the new regulation also addresses SMS fraud. Starting September 15, 2024, a more stringent SMS filtering mechanism will be activated. Telecom operators will block all text messages from senders (aliases) that have not been pre-registered in the database of the National Commission on Markets and Competition (CNMC).
This measure aims to combat the increasingly common ‘smishing’ scams, where criminals impersonate banks, delivery companies, or government agencies to send messages with malicious links. After the new rule is implemented, users will only receive messages from entities with verified, legitimate identities, significantly reducing the risk of being scammed.

Measures Designed to Protect Consumers
To further protect consumers, the new ‘400’ number range is designed for one-way communication. This means users can only receive calls from these numbers but cannot call them back. This feature effectively prevents high-fee fraud or other types of scams that can occur from calling back unknown numbers.
This series of measures is a concrete implementation of the Customer Service Law (Ley de Servicios de Atención a la Clientela) passed in December 2023. The law explicitly requires commercial calls to be distinguished by a dedicated numeric code to protect consumers’ right to know and right to choose.
Results Achieved and Continued Efforts
The Spanish government’s plan to combat telecom fraud is already showing results. According to Óscar López, the Minister for Digital Transformation and Public Function, Spanish telecom operators have successfully blocked over 300 million fraudulent calls and 26.6 million malicious text messages since the plan was implemented.
The government also encourages the public to use the ‘017’ service hotline. This is a free, confidential helpline managed by the National Cybersecurity Institute (Incibe), providing citizens with assistance and guidance on cybersecurity. The full implementation of these new regulations marks a significant step for Spain in building a secure and transparent digital communication environment.