The TAPI Server

The TAPI server (Tapisrv.exe) is the central repository of telephony information on a user machine. This service process tracks local and remote telephony resources, applications registered to handle Assisted Telephony requests, and pending asynchronous functions, and it also enables a consistent interface with telephony service providers (TSPs). Please see The Microsoft Telephony Programming Model for a diagram illustrating the relationship of the TAPI Server to other components and an overview of their roles.

On Windows 95, Windows 98, and Windows NT, Tapisrv.exe runs as a separate service process. On Windows 2000, it runs within the context of Svchost.exe. When an application loads a TAPI DLL into its process space and performs an initialization operation, the DLL establishes an RPC link to the TAPI Server. The TAPI Server loads telephone service providers (TSPs) into its process space. Regardless of how many applications access a given provider's devices, only one instance of a given TSP will exist.