The main functions that TAPI can enable are the basics required for setting up calls, conducting conference calls and forwarding calls. In addition, typical office functions, such as database access, are made possible via Computer Telephony Integration (CTI). TAPI can be used for ISDN, analogue telephony, mobile telephony and voice over IP.
As part of the integration of telephony applications on computers, the TAPI can initiate calls from a PC, view data on incoming calls or indicate the status of extensions. In the Windows environment TAPI is the central component of Computer Telephony Integration, exchanging data with the telephone system. Communication with the telephone system is managed by the TAPI Service Provider (TSP). For example, email programs, such as Microsoft Outlook or IBM Notes, often use the TAPI to access software phone functions from within the software. One example of this is the function that allows stored contacts to be called directly with just a mouse click. Journal functions allow the person dealing with the call to directly enter contact data into a system during a call. This enables other users to immediately see the complete call history of a customer. This helps call centres to work much more efficiently.