The document discusses open source software (OSS) and modular OSS projects like Asterisk and FreeSWITCH. It describes how OSS is used in telecommunications and provides examples of OSS components like codecs, conferencing, and SIP. The document outlines the anatomy of voice applications and how OSS powers web applications and hardware. It introduces OpenVBX, an open source voice application builder, and how it is built with other OSS projects. OpenVBX allows creating modular applets and developing plugins. The future of OSS and OpenVBX is discussed.