An Anti-SMS-Spam Using CAPTCHA

Today sending spams has turned to be a major problem in the Internet. In last 20 years, the Internet and mobile communication growth in parallel. So the spams are also born on the mobile phones as the form of SMS (short message service) spams. In this paper a new method is proposed for filtering SMS spams using CAPTCHA (completely automatic public turing test to tell computer and human apart) systems. CAPTCHA systems are used to distinguish between human users and computer programs automatically.In this method, the picture of an object is sent as an SMS picture message. Also name of that object and name of three other objects are written in the SMS as a multiple-choose question. The user should select the name of that object from a list of four object names and send the number back in reply as an SMS text message. If the SMS sender can pass the CAPTCHA test, it will be identified that SMS is legitimate.