Same here - calls but no message.  Using 920-424-2046 as well as 920-424-3991.  
I'm thinking these are prank calls, so adding them to my black list.
Problem solved.

Received a couple calls from this number in the past 2 days. They do not leave a voicemail.  Appears to be from Oshkosh, which is 30 miles away.  Tried calling it back, but it just kept ringing and ringing...no answer, no voicemail/answering machine...nothing.