I have a PHPFox ([login to view URL]) website. It has the option of Google Authenticator generates 2-step verification codes on your phone.
Just like 2-step verification, a user can register multiple phones to access their account.
The personalization I need is to enable a user to register only a cell phone linked to their account.
My site is restricted access and the intended purpose is to prevent a user from sharing their password or passcode to another user.