For Android phones without this feature built in, try the Block Calls app by Jachness. It's not on F-Droid, but the source code is available on GitHub. Play S

For Android phones without this feature built in, try the Block Calls app by Jachness. It's not on F-Droid, but the source code is available on GitHub. Play Store listing: https://play.google.com/store/apps/details?id=com.jachness.blockcalls https://play.google.com/store/apps/details?id=com.jachness.b... GitHub repo: https://github.com/jachness/blockcalls https://github.com/jachness/blockcalls