International Journal of Computer Applications
VoIP (Voice over Internet Protocol) enables user to make calls through internet. VoIP system is popular because of its rich features. VoIP uses Session Initiation Protocol (SIP) for initialization, termination and tearing down of a session between two communicating entities. Due to its rich features VoIP has received wide acceptance and becoming one of the mainstreams in communication network, increased use of this includes scams and security concerns. Vulnerabilities in the SIP protocol enable hackers to inject control signals and hijack calls.