The number called me twice in the early morning - around 6am CST, which means it was only around 7am in MD, too early for it to have been a business or creditor.  When I called the number back at 8am, it rang and rang several times.  Finally a voicemailbox picked up and there was no information as to where I had called, who the owner of the number was or anything else.  It might not be a scam, but it's better to be safe than sorry!