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Telephony overview

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Applies To: Windows Server 2003, Windows Server 2003 R2, Windows Server 2003 with SP1, Windows Server 2003 with SP2, Windows Server 2008, Windows Server 2008 R2, Windows Server 8 Beta

Telephony overview

Telephony Application Programming Interface (TAPI) integrates telecommunications with the computer. TAPI supports both traditional (or PSTN) and IP telephony to provide voice, data, and video communication. Supported hardware includes sound and video cards, modems, ISDN lines, ATM networks, and cameras. With this, you can communicate over direct connections to local computers, phone lines, LANs, 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 may 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.

  • TAPI manages all signaling between a computer and a telephone network, including basic functions such as dialing, answering, and hanging up a call.

  • TAPI includes supplementary functions that are found in PBX, ISDN, and other phone systems, such as hold, transfer, conference, and call park.

  • TAPI provides access to features that are specific to certain service providers, with built-in extensibility to accommodate additional telephony features and networks.

  • TAPI allows users to make audio and video telephone calls over IP networks using the H.323 protocol and IP multicast video conferencing.

  • TAPI includes Quality of Service (QoS) support to improve conference quality and network manageability.

These capabilities enable TAPI to unify IP and traditional telephony and support programs that effectively work the same way over intranets and the Internet as they do over the traditional telephone network. Furthermore, the current version of TAPI provides compatibility with previous versions to support existing telephony programs.

HyperTerminal and Network Connections are communication programs that use TAPI and that are provided with the Microsoft® Windows Server 2003 family. 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.