You may have never heard of spoofed caller ID numbers. Telephone callers can and do get you to believe the ID you see is valid. Block all calls is the only way to block spoofed numbers. The most aggressive marketers will generate hundreds of spoofed IDs.
This number has been calling my home phone here is S.FL several times each day in the past week. They do not leave a message and it comes up on my caller ID as Private Name.
We see ALLSEC in caller ID and the minute the answering machine kicks in they hang up - am tempted to go to a payphone (OMG...do they even still exist?) and call so it's not traceable back to me....