How can I check if a user already exists before creating an auth account

[trickeyd]

Hello - apologies if this is answered in your docs somewhere, but I have scoured them, your issues as well as stack overflow but can find the answer I need.

We have an issue in out app that once users get signed out, they cannot remember the method they last used to login, and end up creating a new account by mistake. Currently the start point for both login and signup are the same buttons, so if there is no account with the chosen method, one is just created.

To get around this we intend to make the user specify whether they are attempting to log in, and then check if a firebase account exists for the credential in question.

For email I think I can achieve this using fetchSignInMethodsForEmail as we have firebase set to not allow the same email between login methods. But I see no way to achieve this for phone number

So just to be clear - I want to check if a phone number already has an auth account attributed to it prior to logged in without creating a new account.

Thanks in advance for any help you can give me on this.