THE BEST WAY I DEAL WITH THEM IS TO WASTE THEIR TIME, TELL HIM/HER THAT YOU WILL PUT THEM THRU TO WHO EVER IS CALLING BUT ONLY AFTER YOU SLOWLY ASK WHO IT IS. ACT STUPID OR NEW LIKE YOU DONT KNOW HOW TO TRANSFER THE PHONE CALL ASK FOR SPELLING OF NAME OF THEIR COMPANY, ETC. ANYTHING TO WASTE THEIR TIME. THEN OF COARSE LEAVE THEM ON HOLD - THEY WILL HANG UP OF COARSE BUT AFTER A FEW TIMES THEY STOP CALLING.