Adding unknown numbers to block list
I didn't read the manual when I got my phone and couldn't figure out how to add randoms to the blocked list. Surprisingly didn't find anything on the webz saying how to natively do it and I didn't want to install an app so I downloaded the manual and read it. Turns out it's pretty simple.
To add random unknown phone numbers to the block list, go to your call history screen. From here long press the phone number and a menu pops up. Choose block contact. That's it.
If you want to see who all is being blocked, click the menu hamburger on the top right of the screen to get to your blocked list and it's screens.
Hope this helps someone else out as well.