In this tutorial, we'll walk through the steps to implement phone number authentication in a Flutter app using Firebase Auth. We'll also create a beautiful UI with individual OTP input boxes and a custom button. This tutorial is intended for testing purposes only and demonstrates essential steps for setting up Firebase phone authentication in a Flutter project.

🔑 For starting the project:
Setting Up Firebase Project
Create a new Firebase project.
Enable Phone Authentication in Firebase Authentication settings.

Configuring Firebase for Android in Flutter
Download and add the google-services.json file to the project.

Set up SHA-1 and SHA-256 keys for secure communication with Firebase:
Open a terminal.
Run this command to get the SHA keys:
keytool -list -v -alias androiddebugkey -keystore ~/.android/debug.keystore
Add the generated SHA-1 and SHA-256 keys in your Firebase console under your Android project