I got the exact same thing.  The 720 area code incoming call was not answered immediately.  I called it back, and someone picked up.  In the background, I could hear multiple voices.  It was obvious that it was from a call center.  However, if it was from a legitimate business, the call would not be routed directly to a specific person.  It would go through a PBX.

I told him I was on the do not call list.  Twenty minutes later, I got the call from the 347 area code.  I could not get to the phone in time, and they never left a message.