If you haven’t Firebase Project Account ? Click here for create project see the steps show in Firebase Setup.

Follow below steps for Phone Login in your project:

1. Go to Firebase https://firebase.google.com/.
2. Now click on Get Started button
   
3. Now select your project if created or create your project by click on + Add Project and google-services.json
   NOTE : How to create Project and set google-services.json setup show in above Firebase Setup
4. On left hand side panel click on setting icon. On click Setting button pop open open. In that click on Project Settings
   
5. Scroll down click on your package and add SHA-1 and SHA26 Key for debug and release.
   NOTE : How to generate SHA-1 and SHA26 steps are mention above. You can see in document left hand menu panel and click on Firebase SHA Key
6. Now click on Add New Provider button and click on Phone for add new provider.
   
7. Now Enable the toggle give support Phone and click on Save> button.
8. Remeber to add all the dependencies in build.gradle which mention in above Firebase Setup
   
9. Now you need to app check for firebase security purpose, so go to your firebase console and click on register button so you can see 2 options reCAPTCHA & reCAPTCHA Enterprise

10. First start with reCAPTCHA verification to follow those stapes

11. Now start verification of reCAPTCHA Enterprise to follow those steps

12. Now Stop your web app from your device and the run web app again and try to do Phone Login.