called at 6:18 pm

We never pick up unknown callers.  There are just too many.  This one leaves a message that says if this is not <first> <Last> name to hang up.  Then it says that if this is that person to wait 30 seconds.  Then it says that by not hanging up the person acknowledges that this person is indeed the person they are calling and to wait 3 seconds to find a place to assure their privacy.
Then they say to call 800-859-7435 about a debt owed. We have never called that number.  We know 2 things.  The person who they are tring to call has been dead for 2 years and that the 866 number on the caller ID is hard to track down because they are usually hard to track down.  The caller Id number is associated with the 800 number.

says if this is not brian a mathison.....etc.

I've received several calls from this number. When I answer, a recording says "If this is [my name], press 1. If you are not [my name], press 2. I've pressed 1, usually nothing happens and I hang up. This time, I pressed 1. A man said "hello is this [my name] and the call was dropped or disconnected. My family and I don't have minutes to waste on this nonsense. PLEASE stop calling. We dont' have anything you want and vice versa!

They've called many times, but seems like we're never around or don't like to pick up the phone when the caller ID says a number we are not familiar with.