These are machine generated calls for lead companys like...Lending Tree, Double Positive, Salesgenie, Lowermybills.com are a few examples. (look them up)
Here's how it works....
They call you...you pick it up and say "Hello", the computer recognizes a human voice and then in an blink connects you to an operator. She thanks you for answering and wants to know what type of loan you need or have questions about. She/He takes some basic information...(loan amount, credit rating, type of house, etc) and places you on hold for a representive. Once this is done...the operator then calls a company that has purchase leads from them at a rate of...$40 to $100 each. Independent companies or Large corporate companies buy these leads. Believe it or not...you may hang up the phone on the Sales person once you fully relize what is going on...but you have just cost that loan officer/company that dollar amount. A company may spend $1000 on leads and never close a deal.
Hope this answers