Additionally you can also set it to only allow calls from numbers listed in your contacts.
If the app is enabled and you receive a call from a number listed on one of the block lists, then the call is hung up and a notification about the suppressed call is shown.
Currently only the download of numbers listed on the swiss K-Tipp website (https://www.ktipp.ch/service/warnlisten/detail/w/unerwuenschte-oder-laestige-telefonanrufe/) is supported. This may change in the future. If you want additional lists to be supported, please drop me a note about the source you want to see supported.