A cost-effective SMS OTP service is designed for sending One-Time Passwords (OTPs), which are unique codes created for one-time use. The OTP is sent to the user via Short Message Service (SMS) and is utilized to confirm identity or facilitate authentication. This service plays a crucial role in two-factor authentication for ensuring secure transactions. Typically consisting of a 4 or 6-digit number, the code can only be used once within a specified period. Incorrect entries or entries made after the designated timeframe will result in an unsuccessful transaction.