Can I look up the carrier for a Dutch phone number via API?

Yes. Telebase returns the carrier, number type, active status and country for any Dutch phone number in a single API call. It covers KPN, Vodafone NL, T-Mobile NL and their MVNOs. Pricing is $0.20 per SIM swap check, with carrier data included and no annual commitment.

How do I detect VoIP numbers in the Netherlands?

Telebase returns a number_type field for each lookup. A value of VoIP identifies numbers routed through internet telephony providers rather than the Dutch mobile or fixed-line networks. This is returned with every SIM swap check, at $0.20 per check.

What format should I use for Dutch phone numbers?

Pass Dutch numbers in E.164 format. Remove the leading zero and add +31. For example, 06 12345678 becomes +31612345678.

Is SIM swap detection available for Dutch numbers?

SIM swap detection for Dutch numbers is launching. The current API response returns sim_swap: UNKNOWN. SIM swap is live in the UK and Germany, with more markets on the way. Contact hello@telebase.io for early access.

Netherlands

Phone number lookup API for the Netherlands

Telebase returns the carrier, number type (mobile, landline or VoIP), active status and country for any Dutch phone number in a single real-time API call. Dutch mobile numbers run across KPN, Vodafone NL, T-Mobile NL and a wide range of MVNOs. Telebase resolves the serving network in real time. Pricing is $0.20 per SIM swap check, with carrier data included and no annual commitment.

Why Dutch fraud and KYC teams use carrier data

The Netherlands is home to a dense fintech ecosystem and one of the most payment-digitised consumer markets in Europe. iDEAL, open banking and a high rate of mobile-first financial services mean phone numbers are a central authentication credential. That makes them a target.

Dutch firms regulated by DNB or the AFM are expected to have effective onboarding controls. A number lookup at onboarding identifies VoIP numbers, inactive lines and carrier anomalies without adding friction for the customer. It is particularly useful for firms seeing cross-border applications, where a Dutch-format number may be served by a foreign carrier.

What Telebase returns for Dutch numbers

carrier: the network currently serving the number, including MVNOs hosted on KPN, Vodafone NL and T-Mobile NL
country: NL for Dutch numbers
number_type: mobile, landline or VoIP
status: whether the number is currently active on the network
sim_swap: launching for the Netherlands. Returns UNKNOWN today.

Example: Dutch mobile number lookup

Request

GET https://api.telebase.io/lookup?phone=%2B31612345678
Authorization: Bearer tb_live_xxxxxxxxxxxxxxxxxxxxxxxxxxxx

Response, 200 OK

{
  "phoneNumber": "+31612345678",
  "active": true,
  "carrier": "KPN",
  "country": "NL",
  "numberType": "mobile",
  "simSwap": "UNKNOWN",  // launching
  "simSwapAt": null
}

Dutch number formats

Pass Dutch numbers in E.164 format: remove the leading zero and prefix with +31. A Dutch mobile number 06 12345678 becomes +31612345678. Dutch landlines follow the same pattern: 020 1234567 becomes +31201234567.

SIM swap detection for Dutch numbers: launching

SIM swap fraud targets Dutch fintech and payments platforms in the same way it targets the rest of Europe. An attacker who takes control of a customer's Dutch mobile number can intercept OTPs and pass step-up authentication checks. Telebase is registering SIM swap feeds with Dutch mobile operators and will return a recency signal when live. The field currently returns UNKNOWN. Early access is available for Dutch teams who want to integrate ahead of general availability.

Request early access