IRRITATING SPAM CALL FROM 0210138070

Non stop calls when you answer no one comes to the phone, i called back the phone is not even ringing. VERY IRRITATING !!!! i have been blocking numbers but they seem to just keep calling ! HOW can we stop these SPAM CALLS?? This is enough to tick you off especially when you answer and there is no one on the other line - this after numerous calls non stop....