I have a cell-phone and I do not answer unknown numbers.  Someone called at 11:38 AM on 10/11/2013 and did not leave a message.  This is the third time they have called my phone in the last two months.  My phone number is registered on the national Do Not Call List (https://www.donotcall.gov/default.aspx) and I reported this call to them.  I wonder if they are just trying scam people like us!