Implementation considerations in a SIP based secure voice over IP network

The spread of IP-based LANs and the increasing use of voice transmission over these IP networks and the Internet have supported the growth and evolution of enterprise voice over IP (VoIP) systems. High quality IP telephony services over the Internet are becoming mainstream and are being implemented in a large number of service provider and enterprise networks. Many vendors are producing packages to take advantage of these telecommunication trends. These applications and services potentially introduce security leaks into a private network and also security issues across networks. These security issues arise due to the accessibility of the security interfaces, which is in turn due to the requirements of the VoIP protocols. Clearly, with the potential widespread implementation of packet networks, the security aspect of VoIP is becoming as important as quality of service (QoS) and next generation application issues. The paper takes an introductory look at the integration of standard security schemes with standard VoIP protocols as would be typically applied in a business type environment. Comparative analyses of the effects of firewall and VPN techniques on the quality of a single SIP-based voice call are carried out. The results of these assessments show that there is minimal negative impact on the quality of a single VoIP call when standard security schemes are implemented. It also provides some insight into issues to consider when implementing a secure, high quality VoIP network, especially for small-medium-micro sized enterprises (SMME)