You may disturbed with spam calls or unwanted calls or call center calls. Then I think. This is best for you to block unwanted calls & blocking incoming calls. Here it can block all unwanted & unsaved contacts automatically. Also you can block robocalls and block phone number which comes from different call centers. Just put the call number in blacklist that's it.
Inzeru has designed Block Incoming calls that falls into the Communication category. The latest update of the app was released on Oct 1, 2020 and this application was downloaded by over 100K users. Block Incoming calls has the overall rating 3.8 on Google Play.
Pay attention to advertisements and in-app purchases while launching this application. You can download the .apk installer of Block Incoming calls 5.22.5 for free and take a look at users' reviews on Droid Informer. The file size doesn't exceed 8 MB and the app can be launched flawlessly on Android 4.1 and above. The security report shows that the app is safe.