Using Captchas to Mitigate the VoIP Spam Problem

Voice over Internet Protocol (VoIP) is one of the emerging technologies today. This application offers the user a service by which one can call another person at a low cost as compare with traditional phone services. One drawback to the Internet is spam, which are unsolicited or unwanted objects which often appear as unwanted messages in various email applications. For VoIP, spam refers to unsolicited and unwanted calls by the VoIP user. In this paper, we have purposed a solution to prevent the spam in VoIP. The CAPTCHA (Completely Automated Public Turing Test to Tell Computers and Human Apart) method aims to determine whether the call is coming from a human or a machine. The key contribution of this paper is a proof-of-concept implementation of a CAPTCHA mechanism to prevent VoIP Spam.