I’ve been asked to write some .NET code that integrates with a phone system using a TAPI API. I read that there is no .NET interface for this API ( http://support.microsoft.
Actually, TeleTools has an excellent set of controls for any TAPI or SIP device and Visual Studio. The new version has a a new set of controls that is even easier to use for 90% of the applications out there so you don't have to learn a large set of events, methods and properties. A wrapper around TAPI is still way too much work than a good set of controls that do most of the work for you. Most applications like caller id and dialing are only a few lines of code. In addition, ExceleTel is the only telephony company with TeleScope, which is a prototyping, logging, learning tool that is unique. The logging will save you a lot of time and let you see exactly what your device/phone line/application is doing.
ExceleTel has been around for over a decade working with TAPI and consulting with the manufacturers who write the TAPI drivers (TSPs) to make their devices work. You can find a lot of information on the website, www.exceletel.com, and you can get more info on the tapi for win32 newsgroup where we all share information.
FULL DISCLOSURE: Fred works for Teletools (http://www.microsoftfaqs.com/msg/14811958.aspx)