Voicemail left on my cellphone: "Hello, this is Andrea Pierce. How are you doing today? Are you there?"  I don't know this person and I don't answer calls from anyone not in my contacts!

called my number 9/7- I answered and there was no response on the other end. call was ended

Just called on 09/07 at 12:00pm EST and did not leave a voicemail. More than likely spam.

Received call:   "Hello, this is Andrea Pierce. How are you doing today?"
She's a recorded voice, but somehow answered my question of, "Are you a real person".
She answered, "Of course, I'm a real person".
She wants to install a "free" security system in my home and all I have to do is put a 6" sign in my yard.  Ha!
I yelled, "No" into the phone and the call disconnected.
Andrea has been blocked.