TAPI stands for Telephony Application Programming Interface and is a programming standard provided by Microsoft within their Windows operating system. It allows software developers to produce telephony software that will work with any modem, as long as that modem is TAPI-compliant.

Each modem can be used to establish a data connection using the standard Windows TAPI driver. But for a voice modem to work with Windows TAPI, the modem must have voice drivers and sound devices. The voice drivers are interfaced with Win 9x/Me through UniModem/V(and Win 2k/XP through UniModem 5), Windows' universal modem voice drivers. Audio devices (or Wave Devices) for the voice modem are usually provided by the manufacturer.