Editing Telephony Application Programming Interface (section)

==TAPI 2.x vs TAPI 3.x==
It is a common misconception that '''TAPI 3.0''' (or '''TAPI 3.1''') replaces '''TAPI 2.x'''.

TAPI 2.x and earlier versions were written in [[C (programming language)|C]]; the API uses pointers to structures. Consequently, TAPI 2.x is easy to access from C or [[C++]] applications, but it can be awkward to use from many other [[programming language]]s.<ref>{{Citation |last=Smith |first=Mark |title=markjulmar/atapi.net |date=2025-03-24 |url=https://github.com/markjulmar/atapi.net |access-date=2025-03-24}}</ref>

TAPI 3.x was designed with a [[Component Object Model]] (COM) interface. This was done with the intent of making it accessible to higher level applications such as developed in [[Visual Basic|VB]] or other environments that provide easy access to COM but don't deal with C-style pointers. 

TAPI 3.x has a slightly different set of functionality than TAPI 2.x. The addition of integrated media control was the most significant addition. But TAPI 3.x doesn't include all functionality that TAPI 2.x does, like support for the Phone class.

One very notable issue with TAPI 3.x is the lack of support for managed code ([[Microsoft .NET|.NET]] environment). As documented in Microsoft KB Article [http://support.microsoft.com/default.aspx?scid=kb;en-us;841712 841712], Microsoft currently has no plans to support TAPI 3.x directly from .NET programming languages. However, Mark Smith has provided a managed C++ library called ITAPI3<ref>{{Cite web|url=https://github.com/markjulmar/itapi3|title = ITAPI3 - Managed TAPI 3.0 .NET wrapper|website = [[GitHub]]|date = 15 March 2021}}</ref> and a 2.x wrapper for .NET.<ref>{{Cite web|url=https://github.com/markjulmar/atapi.net|title=ATAPI.NET - Managed library for TAPI development with .NET|website=[[GitHub]]|date=12 November 2021}}</ref> Other developers provide libraries to work indirectly with TAPI enabled PBXs.<ref>{{Cite web|url=https://sourceforge.net/projects/siptapi/|title = Siptapi}}</ref>

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.