It was an elderly sounding woman who asked for the head of the household. I told her that they weren't here. She then said that there would be no message and she would call back later. Before I could tell her not to call again, she hung up.
Got a call from the same number at 3pm today, Nov 20. No message was left. I do not know anyone from area code 313. Must be someone with not much to do or someone lonely:-( ???