What phone signals should a neobank check at onboarding?

At minimum: number type (to screen VoIP and disposable numbers), carrier (to cross-check against the applicant's stated country), and active status (to confirm the number is reachable on the network). SIM swap detection adds account takeover protection by flagging numbers whose SIM was recently changed.

Why do neobanks need to screen VoIP numbers at sign-up?

Non-fixed VoIP numbers are cheap, disposable and commonly used for multi-accounting, promotional abuse and synthetic identity fraud. Screening them at onboarding is the single highest-value phone check for a digital bank because it stops the most common attack vector before an account is created.

Is phone intelligence enough for neobank KYC compliance?

No. Phone intelligence is a signal layer, not a replacement for document verification, biometric checks or sanctions screening. It catches fraud types those checks miss, such as real documents paired with burner phones, and works alongside them in the onboarding flow.

How does per-query pricing work for high-volume neobank onboarding?

Telebase charges per successful lookup with no annual commitment and no monthly fee. Every account starts with 100 free queries. Larger volumes are priced lower on request. This means cost scales with actual onboarding volume rather than a fixed platform fee.

Neobank fraud prevention

Phone Intelligence for Neobank Onboarding

Neobanks onboard customers in minutes, which means fraudsters open accounts in minutes too. Phone intelligence lets you screen every sign-up for VoIP and disposable numbers, confirm the carrier and active status of the number provided, and check for recent SIM swaps. Telebase returns all of these signals in a single API call, priced per query with no seat licence, so the cost scales with your onboarding volume rather than your headcount.

The problem: speed creates exposure

Digital-first onboarding is the product. Customers choose neobanks precisely because they can open an account in under five minutes without visiting a branch. But that same speed compresses the fraud window. A synthetic identity application, a multi-accounting ring, or a money mule set-up looks identical to a legitimate sign-up until the damage is done.

Document verification and biometric checks catch forged identity documents. They do not catch a real passport paired with a burner phone. The phone number is the one identifier a customer provides that can be checked against live carrier records in real time, without asking the customer to do anything extra.

What phone intelligence catches at onboarding

A single lookup against the phone number provided at sign-up returns several signals, each useful on its own and stronger combined.

Signals returned per lookup

Number type: is the number mobile, landline, fixed VoIP, non-fixed VoIP, toll-free or voicemail? Non-fixed VoIP numbers are cheap, disposable and disproportionately used for multi-accounting and promotional abuse. Flagging them at sign-up is the single highest-value screen for a neobank.
Carrier: which operator issued the number? A number claimed as a UK mobile that resolves to an overseas VoIP carrier is a strong risk signal.
Country: does the number's country match the application? A mismatch between the stated address and the phone number's origin is worth a second look.
Active status: is the number currently reachable on the carrier network? A disconnected or inactive number submitted at onboarding suggests the applicant does not actually use it.
SIM swap: has the SIM card behind the number been recently changed? A recent swap is the most common precursor to account takeover via OTP interception. More on SIM swap detection.

Where each signal fits in the onboarding flow

Step one: pre-OTP screen

Before spending money sending an SMS verification code, check the number type. If it is non-fixed VoIP or toll-free, either block the sign-up or route it to a higher-friction verification path. This alone stops the cheapest multi-accounting attacks.

Step two: carrier and country cross-check

Compare the carrier and country from the lookup against the applicant's stated details. A UK address paired with a number on a non-UK carrier, or a mobile number that resolves to a VoIP provider, is worth flagging for manual review.

Step three: active-status confirmation

A number that is not currently active on the network is unlikely to belong to a legitimate applicant. Use the active field to confirm the number is reachable before completing the account opening. Where the active check returns a weaker signal source, apply a softer threshold rather than a hard block.

Step four: ongoing SIM swap monitoring

For high-risk actions after onboarding, such as password resets, large transfers or payee changes, a SIM swap check catches whether the number has been recently reassigned to a new SIM. This is the standard precursor to OTP interception and account takeover.

How Telebase works for this

Telebase is a single API endpoint. One call to GET /lookup?phone=... returns carrier, country, number type, active status and SIM swap status in a single JSON response. There is no dashboard to log into, no batch file to upload, and no seat licence to manage.

Response: UK mobile number

{
  "phoneNumber": "+447700900000",
  "active": true,
  "carrier": "EE",
  "country": "GB",
  "numberType": "mobile",
  "simSwap": false,
  "simSwapAt": null,
  "_meta": { "activeSource": "LINE_STATUS" }
}

A clean onboarding response: real UK mobile on a recognised carrier, no recent SIM swap, active on the network via a strong line-status source. active is sourced from LINE_STATUS (network-level check) or VALID (format-only). See the full field reference for details.

This shape is designed for automated decisioning. A fraud engine or AI agent can parse the response, apply rules, and make a pass/flag/block decision without human interpretation.

Why per-query pricing suits neobanks

Neobank onboarding volumes are spiky. A marketing campaign can double sign-ups for a week, then drop back. Seat-based or platform-fee pricing penalises that pattern. Per-query pricing means you pay for the lookups you run and nothing when sign-ups are quiet.

Every account starts with 100 free queries. There is no annual commitment and no monthly fee. You pay only for successful lookups. Larger volumes are priced lower on request.

Regulatory context

The FCA has moved from guidance to enforcement on neobank onboarding controls. Phone intelligence does not replace document verification or sanctions screening. It adds a signal layer that catches the fraud types those checks miss: real documents paired with disposable numbers, synthetic identities using VoIP registrations, and account takeover via SIM swap.

Telebase processes phone numbers under GDPR Article 6(1)(f), legitimate interest for fraud prevention. No additional consent collection is required at onboarding for this purpose. See the full GDPR compliance guide for implementation detail.

Getting started

Telebase is in private beta. Sign up for early access, receive an API key, and run your first lookup in under two minutes. Integration is a single HTTP call, so there is no SDK dependency and no infrastructure change required.

Request early access