OTP SMS: How SMS Verification Works

OTP SMS verification is three separate steps, and the SMS gateway is only responsible for the middle one.

1. Generate the code

Your application generates a short, random, time-limited code and stores it against the user or session attempting verification.

2. Send it by SMS

Your application sends the code as the body of a single-recipient SMS through the API -- the same endpoint used for any other message, not a separate "OTP product". See OTP SMS Tanzania.

3. Verify what the user enters

When the user submits a code, your application compares it against the one it generated and checks it hasn't expired. The gateway plays no part in this step -- it only reports whether the message reached the handset.

Knowing the code arrived

Read the message's delivery status from the API response or a delivery webhook rather than assuming a code was received the moment it was sent.