Spain implements 400 prefix for commercial calls

Starting Saturday, October 17, 2026, commercial calls in Spain must be identified using a specific nine-digit prefix beginning with 400. This measure, part of the Customer Service Law, aims to combat telephone spam and help consumers recognize advertising calls before answering.

The 400 range is reserved exclusively for outbound commercial calls intended to acquire new customers. These numbers are unidirectional, meaning users can receive calls from them but cannot call back. The regulation applies to large companies (those with over 250 employees or €50 million in turnover) and essential service sectors, including telecommunications, energy, finance, and transport.

To complement this regulation, the digital industry has launched soy-yo.es, a free platform allowing users to identify which company is behind an unknown number. While the Organization of Consumers and Users (OCU) views the prefix as a positive step toward transparency, they noted it is not a definitive solution to end all unwanted calls and called for stricter sanctions for non-compliance.