Describe the dangers of answering calls from unknown numbers and provide an example of people pretending to be from an organization to steal from individuals.
Even with a cell phone, one is not safe.  Calls from unknown numbers are answered with "who the h-ll is this, I do not recognize this number."  Followed by, "liar"  "Stop stealing from people and get a real job."  Here is some good advice for everyone.  Neither the IRS, nor Microsoft ever calls people.  I have been called by people claiming to be from one of those two parties.  Both were told what liars and thieves they were.