No phone number SMS passwordless flow


I would like to achieve the following login / registration flow, and looking for the best way to do it:
User inputs email, which is sent to the server. The server uses this email to create a passwordless SMS user, and returns the authentication token to access the backend.
When a user updates then phone number in the backend, the management API will be used again to update the phone number to that account, otherwise, the user will have to specify their email and phone number next time they attempt to log in.

Right now, I can see no way to create an SMS passwordless user without specifying the phone number they will use in the future, and if I create a passwordless email user instead, then they would not be required to input a phone number when attempting to login.

Is there a simple way to achieve this behaviour, or will it require designing the UIs and making all the required API calls manually? Would I create an SMS passwordless user with a “fake” number and then update it myself? Or will I somehow convert a passwordless email user to an SMS user once a number is supplied?

Thanks for any help!

Hey there @Crucial288!

So to begin with. Pretty much when it comes to Passwordless flow, it’s a one that doesn’t allow you for any customisations of the flow steps. The only way to implement Passwordless flow is to adhere to the step by step docs here: