No, graciasThe 400 prefix
What it is, since when it's mandatory and what you can do if they keep calling.
What it is
400 is a range of nine-digit numbers that Spain's National Telephone Numbering Plan reserves for sales calls. It was approved by the Resolution of 14 April 2026 of the Secretary of State for Telecommunications and Digital Infrastructure, published in the BOE (Official State Gazette) on 16 April 2026. Its purpose is to let you know a call is a sales call before you answer.
The resolution builds on Law 10/2025 on customer service, which calls for sales calls to be clearly told apart from customer service calls. (The official texts are in Spanish.)
Since when
Since 17 October 2026, sales calls must come from 400 numbers, and carriers block sales calls that use other numbers, such as mobile or landline numbers.
Good to know
- They're outgoing-only numbers: you can be called from a 400 number, but you can't call it back.
- Customer service doesn't change: service calls from a company you're a customer of don't have to use 400.
- There are gaps: call centres outside Spain, or anyone breaking the rules, can still call from other numbers.
What you can do
1. Filter 400 calls
With «No, gracias» you identify or block them on your iPhone. Some carriers also offer to block the whole 400 range on request: ask yours.
2. Join the Robinson List
The Robinson List is Spain's free advertising opt-out service. Companies running sales campaigns must check it and not call people on it, unless you've given them your consent.
3. Ask the company to stop calling
You can exercise your right to object: ask the company to stop using your data for marketing. Saying so during the call is enough, or you can write to their customer service or data protection officer.
4. File a complaint
If a company keeps calling after you've objected, or calls you without consent while you're on the Robinson List, you can file a complaint with the Spanish Data Protection Agency (AEPD). Note the number, date and time of each call.
Frequently asked questions
Who is calling me from a number starting with 400?
A company calling you for marketing purposes: to sell you something or offer you a service. Since 17 October 2026, sales calls in Spain must come from 400 numbers.
Can I call a 400 number back?
No. 400 numbers are outgoing-only: they're used to make calls but can't receive them.
Is it legal for them to call me from a 400 number?
Yes, using 400 is exactly what the rules require. But it doesn't give them permission to call you if you've joined the Robinson List or asked them to stop.
How do I know which company is calling?
The number doesn't say. Ask for the company's name during the call: you'll need it if you want to object or file a complaint.
How do I block 400 calls on my iPhone?
Blocking numbers one by one doesn't work, as there are a million of them. You can use an app like «No, gracias», which identifies or blocks them all, or ask your carrier. We explain it in how to block 400 calls on iPhone.
I still get sales calls from mobile or landline numbers. What can I do?
If the sales call is made from Spain, it breaks the rules. Note the number, date and time, ask for the company's name and follow the steps above to object or complain.
This guide is for information only and isn't legal advice. Always check the official texts linked above.