Security Implementation for a VoIP Server

VoIP is replacing traditional telephony system over PSTN as a more affordable communication tool on account of convergence of networks. Meanwhile, security issue brings more attention and becomes more important. SIP is based on text message. This makes the protocol easy to implement but also creates opportunity for hackers to steal or modify the messages. There exist a various approaches to secure SIP application such as IP Sec (Internet Protocol Security), TLS (Transportation Layer Security), etc... We applied security implementation on the existed local server by adding credential and filtering ports. IP tables are initiated for each port to list defined rules. QoS performance was verified after applying security approaches. Results showed that this server can still maintain an acceptable service level while offering a secure telecommunication platform.