Telephone Application programming Interface (TAPI) provides a uniform set of commands for any supported telephony device that is connected to your computer.

How TAPS works

When you use a Windows Server 2003 family program to send faxes, connect to a telephone, make a call using lP, join a conference, or perform other TAPIsupported activities, there are three layers of software that enable you to use a telephony device: a program, TAPI, and a telephony service provider.

1.) A program enables you to make phone calls, send and receive data or faxes, or join conferences. Microsoft and independent software vendors provide programs that incorporate TA Pt functionality. Examples include HyperTerminal, which is included with Windows Server 2003 operating systems. Fax Services, another communication program that uses TAPS, is available on an optional basis.

2.) TAPS provides telephony functions for programs, such as dialing.

3.) A telephony service provider translates the commands for a telephony device or telephony protocol. Telephony service providers for modems and severaltelephony protocols are installed with Windows Server 2003 operating systems, and others are provided by independent hardware vendors.

TAPI Works with Telephony Hardware

In place of proprietary solutions that are difficult and expensive to implement, TAN provides a single set of commands allowing hardware and software to come from different sources. When a telephony program requests an action, TAPI determines which telephony service provider supports the device, and the service provider sends the appropriate commands to the device.

For example, the Undimmed (Universal Modem) 5 Service Provider is installed with Windows Server 2003 operating systems. When an program initiates the dialing of a phone number, TAPS sends the appropriate commands to the Unimodem 5 Service Provider, and it sends the correct sequence of commands for dialing the number on the particular modem attached to the computer. The program does not need to know anything about the modem.

With TAPI, the Windows Server 2003 operating system provides a telephony platform. The Windows Server 2003 operating system is the operator that interconnects computer and telephony resources to direct and manage calls.TAPI-based software can provide solutions ranging from complete small office systems or home office systems to PBX front ends that integrate the computer and telephone networks of an organization.

Lines

In telephony-, a line is any media stream (data, voice, or video) supported by a telephony sere ice provider. For a modem, the line represents an actual telephone line. For other devices, it can represent another media stream, such as a gateway to the Internet. Calls are made using a line provided by a telephony service provider. A single line can support more than one call at a time, such as with call waiting and conferencing. The telephony service provider determines how physical devices are represented by telephony lines.

Phones

A phone in TAPI represents terminal equipment that is supported by a telephony service provider. In TAPI, a "phone" closely models a physical telephone, but may not be actual hardware. It includes the concepts of a hookswitch, handset, speaker, microphone, display, lamps, and programmable buttons. As with an actual telephone on your desk, a phone may be used without actually making calls to someone else. For example, you can use a telephone handset to listen to or retrieve voice mail messages.

A phone does not have to represent actual hardware; it can be emulated in software. For instance, this type of phone might be a program that uses TAPI or a telephony service provider. A physical phone is not required to manage a media stream and, although all telephony service providers support lines, not all telephony service providers support phones.