In firebase, we have been using the firebase identity management system with our app. We allow users to register with email & password and separately, they can register their phone with their account.
We are now looking to enable SMS multi-factor authentication and I'm wondering for those users who already have a phone number associated with their account, do we need to go through the "enrolling a second factor" step and have them re-authorize their phone? Or is there a way to just enable multi-factor with the existing phone number already associated with their account and enforce that at login?
Thx