This collaborative project, developing a testbed that enables research on understanding and analysis of vulnerabilities of Voice over IP (VoIP), investigates issues related to Quality of Service (QoS) in VoIP, taking into account possible attacks, identity management, spamming, Denial of Service (DoS) attacks, 911 emergency management, and high availability. Research results will be translated to engineering guidelines for preventing security breaches during development and deployment of VoIP networks.