Definition
OTP (One-Time Passcode)
A short code sent to a phone to verify ownership — and a common target for disposable-number and pumping fraud.
One-time passcodes are widely used for phone verification and two-factor authentication. Because each verification triggers a paid SMS, OTP flows are abused in two ways: disposable numbers farm accounts, and SMS pumping inflates traffic for profit.
Screening the number for liveliness and risk before sending the code defends against both.
Deep dive: How to Reduce OTP and SMS Verification Fraud