From V.E.R.A. -- Virtual Entity of Relevant Acronyms (February 2016) :
TAPI
Telephony Application Program Interface (Intel, MS, WOSA, CTI)
From The Free On-line Dictionary of Computing (30 December 2018) :
Telephony Application Programming Interface
TAPI
(TAPI, or "Telephone Application
Program Interface") A Windows 95 Application Program
Interface enabling hardware independent access to telephone
based communication. TAPI covers a rather wide area of
services from initialising the equipment (e.g. a modem) and
placing a call to voice mail or control of a remote
computer.
[Telephone or Telephony?]
(1995-12-05)