Single “User-Only” Page with SMS Verification?

I am building a relatively simple site for a client and am hitting a wall when it comes to what seemed like a deceivingly easy request.

He wants one page of the site with important info to be only accessible to users who have provided a valid phone number in a registration form for easy followup later on. I have a couple ideas for how to build that functionality, but neither cover every base.

  • Use basic wordpress login/registration functionality and only allow logged in users to see the page. I feel as though sms verification isn’t an option as phone numbers aren’t stored via WordPress’s registration system.
  • Use Orion SMS OTP verification on a basic form hosted on the site. When the user verifies their phone number and submits the form, the password for the password protected private page will be sent via SMS to their provided phone #. With this one, I’m confused as to where I could store the user’s information for easy lookup later on. Would Twilio be an option? or Mailchimp?

Thanks for any advice you can send my way. I’m relatively new when it comes to WordPress dev.