Login with Phone number and OTP for existing users

Need help
1

We have a bubble app with thousands of users already signed up using their actual Email ID and Password. We are planning to move to login using Mobile Number and OTP. For the above action, I was thinking of going with this approach :
Signup :

  1. Email of the user will be input phone number + @randomemail.com
  2. Set Some Temp Password of the user when OTP entered by the user is correct

I think this will work fine for new users and they will always have to log in/signup using OTP.

How do I make existing user login using OTP? We don’t know the existing password of the user and we cannot change it unless we know the old password. Any idea how to make login using a mobile number and OTP easier and without impacting existing users?

2

@rushi - You can handle this as part of existing users’ login workflow. May be you want to tell them, the login method is going to change to OTP instead of password, and ask them to verify the phone by sending/validating the OTP.

In that process, you can also set the temp password of the user (who is logged in), and save the temp password to another field. On subsequent logins, you can use their existing email address (no need to assign a new email address with phone@randomemail.com) and this saved password to login - after validating their OTP text.

I hope this make sense.

Cheers!
Partha.