User validation before phone authentication

Question

I want to validate user phone number exists in Firebase before phone authentication. And if user exists then only OTP verification will start otherwise show error. Kindly help me out please

Answer 1

You can use the Admin SDK to lookup a user by phoneNumber: admin.auth().getUserByPhoneNumber(phoneNumber)

This will help you check if a user record with this phone number already exists.

Learn more by visiting the documentation.

You can create an HTTP endpoint to do so.