Call blocker is your best bet.  Also don't pick up on calls you do not recognize.  These are hard core Indian or Pakistani scammer/extortionists.  You do NOT want to return their calls under ANY circumstances.   They male callers are extremely abusive when they find out you aren't falling for their stupid scams.  These calls are not random.  They have a lot of your financial information and some personal information.  They are predators in search of vulnerable people.  They pick on women, single mothers, the elderly and members of the immigrant community.  Do not return the calls, returning the calls is a signal to them that you feel vulnerable in some sense or another.  Then they just hammer you with more calls.