nOTP is a No-OTP verification mechanism under ExoVerify from Exotel that helps secure your business by verifying customer identity based upon their mobile number.

Available as an SDK for Android phones only, nOTP allows users to verify with absolutely no actions from their end. All they have to do is enter their phone number, and click on the ‘verify’ button. Everything else happens automatically, and the number gets securely verified. nOTP works without an SMS. It is simple and makes number authentication foolproof by ensuring that the mobile number and the user's device are tightly coupled at the time of verification. 

nOTP works with the SDK automatically intercepts a phone call triggered by Exotel to the mobile number seeking verification, allowing you to verify your users seamlessly with zero user interaction.

Using the SDK, you can have nOTP verification into your existing android apps with just a few lines of code.

Please refer to this Sequence Diagram to understand the back-end magic of nOTP