Unknown Call Blocker is a free Android app developed by legalfundaa.in that keeps your phone free from unwanted calls. This app helps to reject calls from unknown numbers automatically. The app checks the number against your contact list and if it is not found, the app will reject the call. This functionality can be turned on/off as per your requirement.

To use the app effectively, you need to give permission to access your contacts. This will allow the app to check whether the incoming call is from a known contact or not. You can give the permission by going to Settings->Apps->Call Reject and granting the required permission.

Unknown Call Blocker works on all Android versions except for Android Version 28. The app is easy to use and does not require any complicated setup. It is a simple and effective solution for blocking unwanted calls from unknown numbers.