Unfortunately for those calls from India I would stay on the line to determine who they are working for. If this is a credit card company you would send them a certified letter demanding that they cease and desist. Check with your state as to the proper procedure. If they don't then you can take legal action.
Also, what's stopping you from changing your number to something non-published? I have done that and actually kept the old number to give out to those who require it. It doesn't ring but I will call out on it for those who want you to call from your home phone number like to activate those replacement cards or customer service. That way they will never get your real number.
-Hal
