These people call continuously with the same last 7 digits, but a different area code every time.  They want to "lower my credit card interest rate".  They won't take no for an answer and even when you tell them you don't have a credit card, they call the next day.  It was frustrating to me, but now, I just blow a nice loud whistle in their ear.  They don't quit calling, but it makes me feel better.