Why can't Samsung s6 phones intercept harassing calls?

S6 How to set the blacklist of incoming calls:

1.G9200 and G9208 How to set the blacklist of incoming calls: Settings-Personal-Incoming Call and Information Interception-Incoming Call Interception-Only the added number is intercepted, and then click+to add the number to be intercepted in the incoming call interception list-save it and view it. Unblock: Delete the blocked number from the call blocking list and choose to turn off call blocking.

2.G9209 Method for setting the blacklist of incoming calls: Apply -VIP mode-click VIP mode-slide on/off, click the following mode 1- Call/information restriction-only reject the blacklist, and then click the blacklist above-"+"to add contacts in the mode; If you need to cancel, delete the contacts in the blacklist list and close VIP mode.