OTP (One-Time Password)

An OTP is a temporary, single-use code — typically 4 to 8 digits — sent via SMS, voice, or messaging app to verify a user's identity during login, transaction confirmation, or account recovery. OTPs are the most common form of 2FA and represent one of the largest A2P traffic categories globally. Delivery speed and reliability are critical, as OTPs typically expire within 30 seconds to 5 minutes.