JumpBox for the Asterisk Telephony System for Windows

JumpBox for the Asterisk Telephony System is self-described as "the world's most powerful and popular telephony development tool-kit." It's a set of building blocks that allows you to construct custom phone-based applications. Drivers for various VoIP protocols. Drivers for PSTN interface cards and devices. Routing and call handling for incoming calls. Outbound call generation and routing. Speech synthesis (aka "text-to-speech") in various languages and dialects using third party engines. Speech recognition in various languages using third party recognition engines. These functions can be layered on top of one another to construct intelligent telephone-based applications. With over two million current users Asterisk is recognized as the world's most popular open source telephony project.