Computer telephony integration aims at the integration of computer-based systems, networks, telecommunication systems, PABX , and voice processing systems.
In order to minimise the time needed to develop applications or to port them to different computers or PABXs , there is a need for standards. It is more efficient to develop applications within a familiar development environment than learning a specific programming language and functions for each application.
The first initiative to develop such APIs originated from NOVELL/AT&T in 1993 through a TELEPHONY SERVICES API (TSAPI ). Many PABX manufacturers supported it (ALCATEL, AT&T, FUJITSU, MITEL, etc.). The objectives were to allow Novell-Netware users to access the PABX functions from their workstations.
The second initiative originated from MICROSOFT, and is called TELEPHONY API (TAPI , or MS-TAPI for MICROSOFT-TAPI ). Its objective is to allow each PC user to operate a standard telephone from any Windows-based application (dialling, voice-mail prompts on the PC screen, etc.). Windows'95 incorporates TAPI functions and a development kit.
Many companies offer applications or hardware platforms with TAPI or TSAPI functions (Dialogic, Rethorex).
So the application developer should know what kind of API he gets with the technology he is buying. The ones mentioned above constitute a comprehensive set of interfaces that will be widely available soon.