Telephony Application Programming Interface (TAPI) integrates telecommunications with the computer. TAPI supports both traditional (that is public switched telephone network or PSTN) and IP telephony to provide voice, data, and video communication. Supported hardware includes sound and video cards, modems, Integrated Services Digital Network (ISDN) lines, Asynchronous Transfer Mode (ATM) networks, and cameras. With this, you can communicate over direct connections to local computers, phone lines, local area networks (LANs), wide area networks (WANs), and the Internet.

In addition to making and receiving calls, programs can use TAPI to provide enhanced telephony features such as caller ID, call routing, voice mail, and video conferencing. Communication programs might identify the caller, recall and display caller information, and even prioritize or route a call, based on customer information.

With TAPI, there is a common standard so that communication programs can control telephony functions for data, fax, and voice calls:

HyperTerminal and Network Connections are communication programs that use TAPI and that are provided with the Windows Vista® and Windows Server® 2008 operating systems. Fax Services, another communication program that uses TAPI, is available on an optional basis. You can also install other Microsoft or non-Microsoft programs to provide additional telephony support. The common interface that TAPI provides enables different communication programs to work together and share communication devices.

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