| Platform SDK: TAPI |
TAPI version 2.0 added a small number of enhancements to the basic TAPI 1.4 functionality. However, there were some major architectural changes that greatly improved its stability. Most of the changes were fundamental changes necessary to bring TAPI to Windows NT and take advantage of Windows NT/Windows 2000 features (full 32-bit support, services, and Unicode). However, these changes were internal to TAPI and had little effect on TAPI applications.
TAPI 1.3 and 1.4 applications (Win16-based applications by way of a thunking layer) work well on Windows NT 4.0 and Windows 2000. However, the effect on service-provider developers was significant. Service providers for Windows NT/Windows 2000 must be fully 32-bit Unicode DLLs that can run in the context of TAPISRV, not in the context of the TAPI application (as did all earlier Win16-based TSPs). TSPs designed for TAPI 1.4 do not work on Windows NT/Windows 2000.
TAPI 2.0 also added the important features of call center support and Quality of Service (QOS) support.
The TAPI system binaries that come with Windows NT 4.0 and Windows 2000 support TAPI versions 1.3 and 1.4 for both Win16- and Win32-based applications. However, only Win32-based applications have access to TAPI 2.0, and only 32-bit TAPI 2.0 (or later) TSPs are supported.