[This is preliminary documentation and subject to change.]
Version 3.0 of the Telephony Application Programming Interface (TAPI) is based on the Component Object Model (COM) and uses DirectShow™ filters to provide access to the media. Developers who are not familiar with COM or DirectShow should consult the relevant Platform SDK sections. Those who are not familiar with telephony should read the overview sections of the TAPI version 2.1 material in the Platform SDK.
TAPI 3.0 does not replace TAPI 2.1 or make it obsolete. Microsoft continues to support and develop TAPI 2.1.