Later when they simple login authentication that cell phone number is used to send factor them a text which they verify by entering into a form field. Sends sms code to validate user login for user validate a registered user to make sure information being submitted is valid checks for proper auth email checks for a good password strength encrypts registration & salts password protection two against csrf. To control cost live demo does not send out login text. A simple two factor authentication written with php & bootstrap sms for css/html. A user registers message with a cell phone number php