This phone number is used by Dane County Emergency Management to send out "Reverse-911" alerts to people that live in the area of an emergency.  It's a pre-recorded voice, and if you don't answer it should leave a voicemail message.  See here: http://www.countyofdane.com/emergency/warning.aspx

A call came in while I was on the other line so I could not pick it up. I dialed back the number less than two minutes after the call came in. Telco message "The number you have dialed is not in service." The caller ID says this is a number belonging to Dane County.