Asterisk open source framework
Asterisk is the substructure for building real-time, multi-protocol communications applications and solutions. Asterisk is the underlying platform for real-time voice and video applications. It subtracts the complexities of communication technologies allowing you to create innovative solutions and products.
Today, there are more than one million Asterisk-based communication systems in use, in more than 170 countries. More often than not it is deployed by system integrators and developers, Asterisk can become the foundation for a complete business phone system, or enhance an existing system, or even close the gap between multiple systems.
The Asterisk framework is built by developers for developers, so if you want to create applications and solutions with it you will need extensive knowledge of Linux, script programming, networking and telephony.