Fraud Prevention

Phone signals for synthetic identity detection

A synthetic identity combines real and fabricated data, a genuine national identifier paired with a fabricated name or date of birth, or a wholly invented profile, to build a credit history that does not map to any real person. Because there is no real individual behind the application, there is usually no phone number with a genuine history either. Carrier, number type and active status checks give a fast, cheap way to notice that gap before it becomes a funded account.

Why synthetic identities are harder to catch than stolen ones

A stolen identity has a real person behind it who will eventually notice and dispute the activity. A synthetic identity has no such person, so there is nobody to complain, no fraud alert to trigger, and the fabricated profile can be nurtured over months, building a credit history through small, legitimate-looking transactions before being used for a larger fraud and abandoned. Document verification can be defeated by a plausible fabricated document or a document template error that is hard to catch visually, and some synthetic identity operations pair fabricated documents with equally fabricated or manipulated selfie images.

The phone number is a harder thing to fabricate convincingly than a document. A fraudster can invent a name and date of birth freely, but a phone number either exists on a real network with a real carrier and country, or it does not. That makes the phone number one of the more reliable places to look for a gap between the claimed identity and the reality behind it.

Where phone signals help

Number type

Synthetic identity applications disproportionately use freshly issued, non-fixed VoIP numbers, since there is no existing personal number to attach to a fabricated profile. See number type detection for fraud for how this screening works.

Carrier and country match

A phone number's carrier and country should plausibly match the applicant's claimed address and history. A mismatch is not proof of a synthetic identity on its own, but it is a low-cost signal worth combining with document and bureau checks. See the carrier lookup API.

Active status

Confirming the number is genuinely reachable on the network, not just correctly formatted, filters out numbers that were never real lines to begin with. See phone number validation for KYC for where this fits an onboarding decision.

None of these signals identify a synthetic identity by themselves. They work best combined with identity verification output, credit bureau checks and document analysis; a phone number with no plausible history is one input into that broader picture, not a standalone verdict.

Where this fits alongside credit and lending checks

Synthetic identity fraud is especially common in products that extend credit based on a thin or building file, since that is exactly the profile a synthetic identity is designed to mimic. If you are building phone-based checks into a lending or earned wage access flow, see securing earned wage access against account takeover for a related pattern, and GDPR-compliant telecom data for KYC for the data handling side of using phone signals in a credit decision.

Signals available today

Live in every response

SIM swap detection is launching. Early access is open now.

Synthetic identity fraud is primarily a new-account risk rather than an account takeover pattern, so SIM swap detection is a secondary signal here. Once a synthetic account is established and aged, the same SIM swap signal becomes part of the broader account-lifecycle risk picture alongside genuine accounts. The simSwap field returns UNKNOWN today in GB, DE, NL and FR while carrier registration completes.

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