Calls late at night. Very strange.

The caller was Indian(with accent) and said due to the stimulus would we be interested in refinancing our mortgage.  Said they weren't a mortgage company but a law firm.  Said I wasn't interested and that I was suspect of who they were (original # was Unknown name 910 0000000).  The supervisor called right back, who said he was Mexican, from this number and said they were calling from San Francisco and then later said Virginia State.  When I mentioned that he wasn't very familiar with the United States Geography he said he was familiar with "f-ing" my mother! Who ARE these people and how do they get our information?