Crypto KYC
Phone number lookup API for crypto KYC
Telebase returns carrier, line type, country and active status for any phone number in a single API call. For crypto exchanges and custody platforms running KYC at onboarding, this adds a fast, cheap signal layer before document checks begin: flag the non-fixed VoIP numbers, inactive lines and country mismatches that correlate with synthetic accounts and money-mule registrations. Pricing is 0.03 USD per query with no contract and no minimum spend.
Why phone number signals matter for crypto KYC
Crypto platforms face a specific onboarding fraud pattern. Because withdrawals are fast, largely irreversible and hard to claw back across borders, the incentive to create fake accounts is high. Fraud rings register at scale using stolen identities and disposable phone numbers, pass a basic document check, build a small account history and then use the account for layering or to receive stolen funds.
Phone number signals do not verify identity on their own. What they do is surface inconsistencies that make a document check more or less worth running. A non-fixed VoIP number, a number registered in a different country from the applicant's stated address, or a number that is not active on any carrier network are all worth knowing about before you spend time on document processing.
The check is also low-friction by design. The customer does not see it. It runs in the background after they submit their number and before the next step of your onboarding flow begins.
Signals and how to use them in a crypto onboarding flow
- numberType: nonFixedVoip. Non-fixed VoIP numbers are the clearest red flag at consumer onboarding. They require no identity check to obtain and are created and discarded in seconds. Flag these for manual review or request a different number before proceeding to document verification.
- active: false. An inactive number means either the number has been cancelled or is not currently reachable on the network. An inactive number at onboarding is worth understanding before the application proceeds, particularly combined with other anomaly signals.
-
country mismatch. If the
countryfield does not match the applicant's stated country of residence, that is worth noting. It is not always fraud (expatriates and travellers have legitimate explanations) but it is a useful flag for a risk review queue. - carrier anomaly. A consumer account served by a wholesale or foreign MVNO is worth additional scrutiny, particularly if combined with other signals. The carrier field lets you inspect this without asking the customer.
What Telebase returns
- active: boolean. Whether the number is currently reachable on the carrier network
- carrier: the network operator serving the number
- country: ISO 3166-1 alpha-2 country code
- numberType: mobile, landline, fixedVoip, nonFixedVoip, tollFree or voicemail
- simSwap: launching for GB, DE, NL and FR. Returns
UNKNOWNtoday.
Example call
curl -s 'https://telebase.fatcatremote.com/api/lookup?phone=%2B447700900000' \
-H 'Authorization: Bearer tb_live_xxxxxxxxxxxxxxxxxxxxxxxx'
{
"phoneNumber": "+447700900000",
"active": true,
"carrier": "EE",
"country": "GB",
"numberType": "mobile",
"simSwap": "UNKNOWN", // launching for GB, DE, NL and FR
"simSwapAt": null,
"_meta": { "activeSource": "LINE_STATUS" }
}
Pass numbers in E.164 with the leading + URL-encoded as %2B. New accounts receive a USD 5.00 starting balance.
Crypto accounts are the most targeted category for SIM swap fraud because withdrawals are fast and hard to reverse. The Telebase simSwap field is live in every response and returns UNKNOWN today while carrier registration completes in GB, DE, NL and FR. Teams who integrate now will receive live swap data as soon as registration clears. Request early access.