I use this:
https://play.google.com/store/apps/d...e.phoneblocker
good because it lets you back up to card/phone so if you reinstall/reset your phone you dont lose all your settings etc.
Also used this in the past too, good though (at the time) no way to back up settings)
https://play.google.com/store/apps/d....easyblacklist
I've used both as intended and apart from looking at the logs you get no idea that a blocked number has rung/texted you, which is kinda the point.