How TAPI supports programs and hardware
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
How TAPI supports programs and hardware
Telephony Application Programming Interface (TAPI) supports programs that share the same communication ports and devices. Communication programs use TAPI to communicate with and control the appropriate hardware. TAPI manages the way programs and their call traffic use ports and devices. Telephony service providers provide support for particular devices or classes of devices.
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Telephony service providers
Telephony service providers are dynamic link libraries (DLLs) that translate the commands for a specific telephony device, carrying out the low-level tasks required to communicate over telephone and IP networks.
How TAPI makes services available
TAPI arbitrates requests from different communication programs, so they can run simultaneously while sharing communication ports and devices. Each service provider controls its hardware. For example, one Windows Server 2003 family program can use TAPI functions to make outgoing calls while other programs are waiting for incoming calls.
Although only one program controls any single call, the devices are available to other programs, and users do not have to close other programs that share a communication port.
Supplied telephony service providers
The following table lists the telephony service providers that are supplied with Windows Server 2003 operating systems:
| Telephony service providers | Used for |
|---|---|
HID Phone |
Human Interface Device (HID) telephone communications |
H.323 |
IP telephony multimedia communications |
Multicast Conference |
IP telephony multiparty conferencing |
Unimodem 5 |
Modems |
NDIS Proxy |
Connection-oriented network devices using NDIS 5 |
TAPI Kernel-Mode |
Connects network devices using NDIS 4 |
Windows Remote |
Client-server telephony |
For more information about telephony service providers, see Telephony service providers.
Additional hardware support
Other service providers can be installed, in addition to telephony hardware or software.
Hardware manufacturers normally supply device drivers for their hardware. To provide telephony services for the hardware, the manufacturers or independent software vendors provide telephony service providers to control the hardware. Each service provider supports at least one device specific to that category of communication, such as a fax board, an ISDN card, a telephone or a modem. Some service providers support several devices, or even an entire class of devices.
For more detailed information about how telephony works, see Telephony Resources.