# SMS verification

With the SMS verification method, a user's phone number is verified by sending an SMS containing an OTP code to this number. In the case of iOS or JavaScript, the user needs to enter the OTP manually or semi-manually in the application, while for Android there is an option of intercepting the SMS message delivery and capturing the OTP code automatically.

To initiate an SMS verification, check the [iOS](https://developers.sinch.com/docs/verification/ios.md) or [Android](https://developers.sinch.com/docs/verification/android.md) documentation. For additional security, it's recommended that you control which verification requests should proceed and which ones not, by listening in your backend for the [Verification Request Event](https://developers.sinch.com/docs/verification/api-reference/verification/verification-callbacks/verificationrequestevent) and respond accordingly. Your backend will be notified on the result of the verification with the [Verification Result Event](https://developers.sinch.com/docs/verification/api-reference/verification/verification-callbacks/verificationresultevent).