This paper is all about the common problems that occur in a VoIP infrastructure. These attacks are called SPIT (Spam over Internet Telephony), Vishing, Phreaking and unsolicited calls. In order to reduce or solve this problem, the proponents developed an application. Findings reveal that an extended caller ID blocking of asterisk server for client computers can solve these rampant problems that happen in a VoIP infrastructure. VoIP do not have enough security to prevent these attacks.