The 400 prefix: phone spam before and after 17 October 2026
Since 17 October 2026, companies in Spain must make sales calls from nine-digit numbers starting with 400. Here we compare what NoCall users reported and looked up over the same number of days before and after the change.
According to the Ministry press release, 400 numbers are one-way: you can receive their calls but not call them back. Operators may block sales calls made from other numbers, and if you get one you can complain to the Telecommunications User Office (OAUT). Calls to manage a contract you already have do not have to use 400.
Check whether a sales call follows the 400 rule
What we compare
Two periods of 19 full days each: before, from 28 September 2026 to 16 October 2026; after, from 17 October 2026 to 4 November 2026. Today is not counted because it has not ended yet.
There is not enough data to draw conclusions yet. Each period needs reports from at least 30 different people and that is not reached yet. We show the figures as they are, without extrapolating: they do not show a trend.
| What we compare | Before28 September 2026 – 16 October 2026 | After17 October 2026 – 4 November 2026 |
|---|---|---|
| Reports on Spanish numbers | 38 | 46 |
| Different people who reported | 22 | 43 |
| Distinct numbers reported | 38 | 46 |
| Reports on 400 numbers | 0 | 0 |
| Lookups of Spanish numbers | 947,086 | 1,226,997 |
| Distinct numbers looked up | 265,118 | 539,544 |
| Lookups of 400 numbers | 0 | 0 |
No NoCall user has reported or looked up a 400 number in these periods yet. That does not mean they do not exist, only that they do not show up in our data yet.
Type of call reported
Before
- Scam15 · 39%
- Spam10 · 26%
After
- Spam22 · 48%
- Scam16 · 35%
- Telemarketing4 · 9%
- Other3 · 7%
Method
- We only count reports a person sent through NoCall (the website or the app) that were approved in moderation: they have a source IP and do not come from imports or generated content. Reports still awaiting review do not count. Minimums count distinct people (by an encrypted fingerprint of their IP), not reports, so one person cannot move a figure. Comments on number pages are not used.
- Reference date: 17 October 2026, as given in the Ministry press release.
- Both periods have the same length in full days (up to 90). Reports are assigned to a day in Madrid time; lookups by the server date.
- A number is a 400 number if, after +34, it starts with 400 and has nine digits.
- We only show categories with reports from at least 3 different people in the period.
- Lookups are searches for a number on NoCall, counted at most once per number, day and connection (IP). We only publish totals. They can include automated traffic, so we count them as lookups, not as people.
Sources
- A partir de mañana las llamadas comerciales solo podrán realizarse desde un número con el prefijo 400 (nota de prensa, 16 de octubre de 2026) · Ministerio para la Transformación Digital y de la Función Pública
- Resolución de 14 de abril de 2026 (BOE núm. 93, de 16 de abril de 2026, BOE-A-2026-8409) · Boletín Oficial del Estado
Other reports
Frequently asked questions
Has spam gone down since the 400 prefix?
NoCall data cannot tell yet. While either period has reports from fewer people than the minimum above, the comparison is not conclusive and we say so.
Can I call a 400 number back?
No. According to the Ministry, 400 numbers are one-way: you can receive their calls but cannot call them.
What can I do if I get a sales call from a number that is not 400?
The Ministry says you can complain to the OAUT. You can also report the number on NoCall to warn other users.