There probably is not one man or woman in this world who has not received an unwanted phone call from an unknown caller. This could be anyone – from an advertisement agent wanting to sell you a brand new dinnerware set to your new boss to your ex-wife. It seems that there is no way to know who is calling you when all you see on the screen are some numbers that you do not recognize and cannot link to any specific person. Missing an important call from your boss or any other significant caller may cause you various problems, and at the same time answering the call and hearing a robot talking and persuading you to buy something that you do not need is not fun either. Fortunately, there is a specific technique which can help you to know who’s calling you prior to answering the phone.