SMS Authentication User Experience
Here is what a user sees when they log in via an SMS authentication system. Logging in via SMS is a three-step process: the user provides their phone number, receives their login code, then they use the code to login.
User sees your captive portal.
User receives login code via SMS.
User logs in.
The user can then enter their code into the captive portal and click to login. Time and bandwidth limits as well as all other network policies that you've applied to the SMS authentication system will now apply to their session.
If they've lost the code, or need the code sent to a different mobile phone number, they can do that from here.