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

Yes. Telebase returns the carrier, number type, active status and country for any UK phone number in a single API call. It covers the four main UK networks and their MVNOs. Pricing is 0.03 USD per query with no contract or minimum spend.

How do I detect VoIP numbers in the UK?

Telebase returns a number_type field for each lookup. A value of VoIP identifies numbers routed through internet telephony providers rather than mobile or fixed-line networks. This is available for UK numbers today at 0.03 USD per query.

Does Telebase support UK number portability?

Telebase returns the carrier currently serving a UK number, accounting for porting. If a number has been ported from one UK network to another, the response reflects the current serving network.

Is SIM swap detection available for UK numbers?

SIM swap detection for UK numbers is launching. The current API response returns sim_swap: UNKNOWN while carrier feed registration is in progress. Contact hello@telebase.io for early access.

What format should I use for UK phone numbers?

Pass UK numbers in E.164 format. Replace the leading zero with +44. For example, 07700 900000 becomes +447700900000.

United Kingdom

Phone number lookup API for the UK

Telebase returns the carrier, number type (mobile, landline or VoIP), active status and country for any UK phone number in a single real-time API call. UK numbers span EE, O2, Vodafone, Three and a long tail of MVNOs. Telebase resolves the serving network, not just the original porting record. Pricing is 0.03 USD per query, no contract, no minimum spend.

Why UK fraud and KYC teams use carrier data

The UK has one of the highest rates of authorised push payment fraud in Europe, and phone numbers are a key attack vector. Fraudsters use virtual numbers and VoIP lines to receive OTPs and pose as legitimate customers during onboarding. UK-regulated firms, including those under FCA oversight, are under increasing pressure to verify that contact details are consistent and plausible before completing onboarding or processing a payment.

A number lookup at the point of onboarding costs a fraction of a downstream fraud loss. It surfaces signals that are invisible to a name-and-address check: a VoIP number where you expect a mobile, an inactive number on an account that should be active, or a carrier mismatch between the number presented and the customer's stated location.

What Telebase returns for UK numbers

carrier: the network currently serving the number, including MVNOs hosted on EE, O2, Vodafone and Three
country: GB for UK numbers, including numbers ported within the UK
number_type: mobile, landline or VoIP
status: whether the number is currently active on the network
sim_swap: launching for the UK. Returns UNKNOWN today.

Example: UK mobile number lookup

Request

GET https://telebase.fatcatremote.com/api/lookup?phone=%2B447700900000
Authorization: Bearer tb_live_xxxxxxxxxxxxxxxxxxxxxxxxxxxx

Response, 200 OK

{
  "phoneNumber": "+447700900000",
  "active": true,
  "carrier": "EE",
  "country": "GB",
  "numberType": "mobile",
  "simSwap": "UNKNOWN",  // launching
  "simSwapAt": null
}

UK number formats

Pass UK numbers in E.164 format: drop the leading zero and prefix with +44. A standard UK mobile 07700 900000 becomes +447700900000. Landlines follow the same pattern: 020 7946 0000 becomes +442079460000.

SIM swap detection for UK numbers: launching

SIM swap fraud is a documented problem for UK neobanks and crypto platforms. Attackers port a victim's number to a new SIM, intercept the OTP, and access the account before the victim notices the loss of service. Telebase is registering SIM swap feeds with UK mobile network operators and will return a recency signal when live. The field currently returns UNKNOWN. Early access is available for UK teams who want to integrate ahead of general availability.

$0.03 per query. No contract. No minimum spend. Billed via Paddle.

Request early access