Introduction to Windows 2000 Telephony and Conferencing

Telephony applications use Telephony Application Programming Interface function calls, also known as Telephony API (TAPI), to provide various types of telephony services to users. This set of Win32 function calls is processed internally by TAPI, resulting in corresponding calls to Telephony Service Providers (TSPs) and Media Service Providers (MSPs) that communicate with their associated hardware and software to provide various types of telephony services to users.

These applications can also use other features of the Windows environment, such as the directory service, databases, and e-mail. TAPI uses standard mechanisms to retrieve and manipulate information offered by telephone systems, such as identification of calling parties, in order to automate the process of associating data with telephone calls. TAPI also provides IP telephony and video-conferencing infrastructure, allowing the deployment of applications that integrate conventional and IP telephony functionality.

A key advantage of using TAPI is that telephony applications can work with any hardware for which a TSP or MSP is available. The abstraction of hardware by TAPI reduces difficulty for developers, and provides flexibility to network administrators. For example, TAPI abstracts the underlying hardware of the telephone system, allowing developers to create telephony applications that work with a variety of telephone systems. Without hardware abstraction, a developer might have to significantly rewrite code to match each type of telephony hardware that their program could be used for. As more developers create applications that can work across an array of hardware, network administrators have more choice in deploying CTI, conferencing, and IP telephony solutions.