Telephony Server and the Telephony API Overview
Applies To: Windows Server 2003, Windows Vista, Windows XP, Windows Server 2008, Windows 7, Windows Server 2008 R2, Windows Server 2012, Windows 8
The Telephony service in Windows Server 2012 provides distributed access to shared telephony devices. For example, a LAN-based server may have multiple connections to a local telephone switch or private branch exchange (PBX). Telephony uses the Telephony Application Programming Interface (TAPI) to enable computer programs to communicate with the shared telephony services. TAPI operations that are invoked by a client are forwarded over the network to the server. The server can then use a non-Microsoft call control between itself and the PBX to fulfill the client's call control requests. TAPI services in Windows Server 2012 enable programs that effectively work the same way over intranets, the Internet, and traditional public phone networks.
TAPI services in Windows Server 2012 have not significantly changed since Windows Server 2003. The documentation for TAPI has not been updated for this version of Windows. You can find all of the documentation for TAPI at see Telephony in the Windows Server TechCenter.