The initial release of TSAPI# is available for review. This offers a TSAPI library wrapped in a C# class. There is also a sample C# application included to test out some of the features. So far only a handful of TSAPI functions are included, with more to come.
The project site also contains downloads for TSAPI client drivers, a CSTA simulator, and a telephony server.
This project is only in the alpha stage, so if anyone is interested in this type of technology feel free to contribute!