Chapter 2 – Security and Privacy 147 SIP Security Mechanisms: A state-of-the-art review

The commercial deployment of VoIP necessitates the employment of security mechanisms that can assure availability, reliability, confidentiality and integrity. The Session Initiation Protocol (SIP) is considered as the dominant signalling protocol for calls over the Internet. SIP, like other Internet protocols, is vulnerable to known Internet attacks, while at the same time it introduces new security problems in the VoIP system. This paper lists the existing security problems in SIP and provides a brief description, followed by a critical analysis, of the security mechanisms it employs