Implementing a VoIP SIP Server and User Agent on a Bare PC

摘要

Bare PC applications run on ordinary desktops and laptops without the support of an operating system or kernel. They provide immunity against attacks targeting an underlying operating system, and have been shown to perform better than applications running on conventional systems due to their reduced overhead. We describe a bare PC SIP server and a SIP user agent designed for VoIP and give details of their internal implementation. The server and user agent include streamlined SIP functions and message handling, efficient CPU tasking, protocol and application intertwining, and direct Ethernet-level data manipulation. The SIP server provides registration, proxy, and redirection services, and the user agent is integrated with lean implementations of the necessary protocols within the bare PC softphone. Bare PC SIP servers and SIP softphones can be used for building secure and efficient low-cost VoIP systems, or deployed in existing VoIP networks with conventional SIP servers and user agents.