Spain’s 400 prefix for commercial calls: what changes in October 2026
Content
From about 17 October 2026, commercial calls in Spain must be made from a number starting with 400, and operators will block the ones that are not. The rule comes from a resolution published in the BOE on 16 April 2026 and applies to companies covered by Ley 10/2025 on customer service. If your team phones customers or leads in Spain, you have days, not months, to move your outbound calling to the 400 range.
Last verified: 1 October 2026. Sources: BOE, Moncloa, digital.gob.es.
Table of contents
- What is the 400 prefix rule?
- Key dates
- Who has to use a 400 number?
- 400 vs 800/900 vs regular numbers
- What happens on the deadline?
- How to comply in five steps
- How Spoki helps
- Frequently asked questions
What is the 400 prefix rule?
On 14 April 2026 Spain's Secretariat of State for Telecommunications and Digital Infrastructures approved a resolution that creates a new numbering range, 400, exclusively for commercial calls. It was published in the BOE on 16 April 2026 (BOE-A-2026-8409) and entered into force the next day.
The design has three consequences:
- Nine digits, starting with 400. Anyone receiving the call can tell at a glance that it is commercial.
- Outbound only. These numbers cannot receive calls, so the person cannot call back. The Ministry presents this as a fraud-prevention measure.
- Opt-out at operator level. Operators may offer subscribers the option to disconnect from the commercial call service delivered through the 400 range.
Minister Óscar López summed it up: from October, everyone will be able to identify commercial calls.
Key dates
| Date | What happens |
|---|---|
| 14 April 2026 | Resolution approved |
| 16 April 2026 | Published in the BOE (no. 93) |
| 17 April 2026 | Enters into force; six-month adaptation period starts |
| On or around 17 October 2026 | Only the 400 range may be used for commercial calls; operators block the rest |
The six-month count is ours, from the entry-into-force date in the resolution. Confirm the exact cut-off with your operator.
Who has to use a 400 number?
Article 1.2 of the resolution obliges the companies within the scope of Ley 10/2025 (services of general interest and large companies selling to consumers in Spain) to use the 400 range for commercial calls, except in the cases exempted by that law's fourth transitional provision. Supervision is assigned to the CNMC.
Two practical points matter more than the legal nuance:
- Blocking happens on the network. Operators, not companies, decide what gets through. A call from a non-400 number that is commercial in nature is at risk of being blocked whatever your legal reading.
- Only operators get 400 numbers. Article 4.1 limits assignment to public telephone service operators or an equivalent category, so you obtain them through your carrier or VoIP provider.
Not sure whether you are in scope? Ask your operator and your legal counsel this week. Treat "we are probably exempt" as a risk, not a plan.
400 vs 800/900 vs regular numbers
| 400 | 800 / 900 | Geographic or mobile | |
|---|---|---|---|
| Purpose | Commercial calls | Customer service | Ordinary lines |
| Direction | Outbound only | Inbound | Both |
| Callable back | No | Yes | Yes |
| Example use | Telemarketing, sales prospecting, customer acquisition | Support, after-sales | Business lines, but not for customer service on mobile |
| Blocked after the deadline if used for commercial calls | No | Not applicable | Yes |
Customer service and after-sales calls are outside the 400 range. The Ministry also clarified that customer service lines must use 800/900 or geographic numbers rather than mobile numbers.
What happens on the deadline?
Once the adaptation period ends, commercial calls may only be made from the 400 range, and operators block those that are not. There is no gradual warning on the line itself: a blocked call simply does not ring.
The resolution itself lists no fines, so the immediate cost is operational: campaigns that go quiet, dialers that show high failure rates and sales teams that cannot reach their pipeline. Users can also report violations to the Telecommunications User Office (OAUT) or the CNMC.
How to comply in five steps
- Audit your outbound lines. List every number, dialer, PBX and vendor that places sales or acquisition calls to Spain, including agency and call-centre partners.
- Classify each campaign. Sales and prospecting go to 400. Customer service and after-sales stay on 800/900 or geographic numbers. Ask counsel about the grey zones, such as renewals or upsell calls to existing customers.
- Request 400 numbers. Ask your operator or VoIP provider, and plan capacity for your peak number of simultaneous calls.
- Reconfigure the dialer and PBX. Switch the caller ID on commercial campaigns and update routing, reporting and CRM syncs. Remember callbacks no longer arrive on that number, so give leads another way to reach you.
- Clean the lists and prove consent. A 400 number labels the call; it does not make it lawful. Keep opt-ins and suppression lists current.
How Spoki helps
Spoki is built for the part of the rule that operators do not solve: running outbound conversations that are consented, traceable and handled well once the person picks up.
- Consent-based outbound voice. Spoki Voice runs campaigns only on contacts that gave explicit GDPR consent, such as CRM customers, marketing opt-ins and web-form leads. Cold lists are not supported by design, which is exactly the profile regulators and operators are targeting.
- Fewer wasted dials. Multi-number rotation, calling time windows and automatic follow-up keep campaigns healthy when numbers change, and every call comes with recording, transcript and summary for your audit trail.
- A route around the callback problem. Because 400 numbers cannot receive calls, pair every call with a WhatsApp message through the official WhatsApp Business API. Leads reply in the channel they prefer, and the conversation lands in the same CRM record.
- Warm handoff to a person. The AI agent qualifies, then transfers to your team by SIP or to a human operator inside the platform.
- EU-hosted, with a signed DPA. Data stays in the EU, recordings are encrypted and retention is configurable.
Explore Spoki Voice, the voice dialer or lead qualification by voice, and see pricing.
Frequently asked questions
When do commercial calls in Spain have to use the 400 prefix?
The resolution entered into force on 17 April 2026 and gives six months to adapt, so the deadline falls on or around 17 October 2026. After that, commercial calls may only be made from the 400 range and operators block those that are not.
What is the 400 number range?
It is a nine-digit numbering range starting with 400, reserved exclusively for commercial calls. The numbers are outbound only: they cannot receive incoming calls, so people can identify a commercial call but cannot call back.
Does my company need a 400 number?
Companies within the scope of Ley 10/2025 must use the 400 range for commercial calls, except for the cases exempted by that law's fourth transitional provision. Because operators will block non-400 commercial calls at network level, any company that phones people in Spain should confirm its position with its carrier and legal counsel.
Do customer service calls need a 400 number?
No. The resolution distinguishes commercial calls from customer service and after-sales calls. Customer service lines use 800/900 or geographic numbers, not mobile numbers, according to the Ministry.
How do I get a 400 number?
Only public telephone service operators, or an equivalent category, can obtain 400 numbers (article 4.1). Companies therefore request them through their telecom operator or VoIP provider, then reconfigure their dialer or PBX to use them.
Are AI voice agent calls commercial calls?
If an AI voice agent is calling to sell, prospect or acquire customers, it is a commercial call and should originate from a 400 number like any other. If it calls an existing customer about their service, it is closer to customer service. Ask counsel to classify each campaign.
Who enforces the 400 rule and where can people report violations?
Operators enforce it by blocking non-compliant commercial calls, and the CNMC supervises the numbering conditions. Users can report violations to the Telecommunications User Office (OAUT) or the CNMC.
Sources
- BOE-A-2026-8409, Resolution of 14 April 2026
- Moncloa press release, 16 April 2026
- Ministry for Digital Transformation press note
This article is general information, not legal advice. Check your situation with your operator and counsel.
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