With the new Mobile Security 3.0, is there a way to block unknown callers?
cohbraz, thanks for the question. There is currently no way to block unknown callers but this is definitely something we are looking into in a future release. Stay tuned!
Then what does it mean on the line in the Block List - where it says Unknown with a check box. I checked it. Today, an unknown caller called and it still rang. Please explain what is that Unknown for?
Hi tbeahm
With Norton Mobile Security (NMS) and the Call Blocking feature if you
enable the Unknown number feature it will block phone numbers where
the person ringing you selects to not display their number.
So a private number that does not show in your caller id ( no number is
displayed ) will be blocked if the Unknown number feature is enabled.
I hope that info helps. :)
Cheers. 
Note - Just to clarify if you have a number that shows in the caller id when
your phone rings and you do not know the number and it is not in your contacts
Call Blocking with NMS will not block the call, it has to be a private unknown
number for it to be blocked. :)
I have a setting for Block all unknown callers in my latest version of NMS. Not sure if this is what you want. Although, I think this would just mean any number not in your contacts would be blocked. Anyone calling for the first time who is not in your contacts would be blocked.
All you can do is try blocking an unavailable or restricted entry in your call log, to see if NMS will accept the entry. Then time will tell if it works.
Please let us know
Does blocking unknown callers also block unavailable and restricted?