Download and install a call blocking application on your device. For this, go to Play Store, and write Call Block in the search list. A list of available apps will come up. Choose the one named as ‘Call Blocker’. Complete the procedure, and install it. This app will cover hardly any space.
Once the app is successfully installed, open it. You will find several options on the first page of the application, such as Blocked Call, Blocked SMS, Privacy Eraser, Backup, and Blacklist. Tap on Blacklist.
Push the button that says ‘Add number’. Enter the number from contacts. You may add multiple numbers just by checking the box right next to every contact. Tap on ‘Add’, and this will create a blacklist.
For more advanced options, go to the app’s settings. You will find the icon at the top right side of the screen. Enter the settings, and select the call blocking rule. By creating a Whitelist, you block every number expect those in the list.