Page "Telephony Application Programming Interface" Paragraph 16

One often overlooked reason an application developer might choose between TAPI 2. x and TAPI 3. x should be the hardware vendors recommendation.

Even though TAPI provides an abstract model of phone lines, telephony applications are still heavily impacted by the specific behavior of the underlying hardware.

Troubleshooting behavior issues usually requires both software and hardware vendors to collaborate.

Because there is almost a 1: 1 relationship between the TAPI Service Provider ( TSP ) interface and the TAPI 2. x interface, collaboration is often easier if the application is designed using TAPI 2. x.

Experience with TAPI 3. x varies significantly between hardware vendors.