OTP Verification Guide: How SMS One-Time Codes Work

An OTP is a one-time password sent to confirm a sign-up, login, or sensitive action. The user enters a phone number, the target app sends a short code, and the code must be entered before it expires.

Because an OTP is time-sensitive, the receiving page should show the order's real expiry and update the code state without requiring a new number for every check.

Expiration limits how long a captured code can be reused. Delivery may also be affected by temporary route availability, an incorrect country selection, a number previously used by the target app, or a delay inside the target service.

• Use the code promptly
• Confirm the target service and country
• Keep querying the same active order
• Do not assume every app accepts every number type

NumFlow displays the order state and verification result in the authenticated order flow. API clients can query the same order until its returned expiry time and should use controlled polling rather than high-frequency requests.