I'm currently reading a book about Windows Workflow Foundation, a part of Microsoft's .Net Framework 3.0. It's a technology to build applications which execute workflows. It's mainly targeted at modeling business processes. WF only provides the engine and tools to be used in own applications. It is highly extensible and could probably be combined with SwyxWare to model workflows reacting on phonecalls or to create phonecalls as part of a workflow.

Maybe I try building a prototype based on the SwyxIt Client API, because that's probably the easiest approach and could be used and extended by anyone.