I never answer calls with numbers (or names) that I do not recognize.  I let it go to voicemail.  If there's a message, I determine further if I know the person/entity.  If no message, I block the caller.  If the message is from someone I do not know, I block the caller.  In the past few months, I have been getting a slew of calls from Indianapolis numbers.  My best guess is that a recent search I did online for mortgage refinancing (and stupidly giving my number thinking lendingtree(?) would provide some usable information, published my number to various mortgage lenders.  Ugh.