The Telephony Application Programming Interface (TAPI) is a Microsoft Windows API, which allows computer telephony integration and enables PCs running Microsoft Windows to use telephone services.
The TAPI was introduced by Intel and Microsoft in 1993.
It defines a client interface and an interface for the TAPI Service Provider (TSP). TSPs are sometimes also named TAPI-drivers. TSPS are created by telephone system manufacturer.
The TAPI itself allows the integration of telephony systems and services into the Windows OS.
The TAPI 1.x, 2.x define a procedural plain C interface and with TAPI 3.0 a Component Object Model (COM) interface was added.