AddTapi.NET TAPI Library

100% Managed Code Telephony in .NET from the Computer Telephony Experts


With AddTapi.NET you can easily add telephony features to your C#, VB.NET or C++ application. AddTapi.NET has everything you need to develop telephony applications such as:

Interactive Voice Response (IVR) Systems
Caller ID Applications
Voice Mail Systems
Phone Dialers
Call Recorders
Notification Systems
Call Tracking Applications
Phone Surveys

AddTapi.NET wraps Microsoft Telephony Application Programming Interface (TAPI) and provides a set of easy-to-use managed classes for developing CTI software. AddTapi.NET supports TAPI 1.3 - 3.2 and works with all TAPI-compatible telephony hardware, from voice modems to advanced telephony boards to TAPI-compatible PBX systems, including:

Dialogic Diva Analog and Digital Boards
Cisco Unified Communications Manager
Avaya IP Office and Avaya Aura
Panasonic KX-TDA and NS
3Com NBX 100
Siemens HiPath
And many others...
AddTapi.NET requires .NET Framework version 2.0 - 7.0 and works with all .NET development platforms including Visual Studio 2005-2022, Visual C#, Visual Basic .NET (VB.NET) and Visual C++.

Why Choose AddTapi.NET?

Easy to use without any TAPI knowledge or telephony programming experience

With AddTapi.NET you can start adding telephony features to your software without spending weeks studying complex TAPI or proprietary telephony hardware API. Unlike other TAPI controls that provide a simple wrapper for TAPI functions, AddTapi.NET does a lot of work under the hood.

100% .NET managed code

AddTapi.NET was designed for .NET from the ground up. AddTapi.NET is written entirely in C# and does not contain any legacy code. Almost all other TAPI controls use old ActiveX technology. With AddTapi.NET you get convenient classes, events and collections that look like a part of the .NET framework. Plus no more problems with ActiveX registration or incompatible DLL versions. AddTapi.NET just works!

Outstanding support by experienced programmers.

Our company has been developing telephony applications for more than 10 years. Our award-winning PhoneTray software is used by more than 100,000 people worldwide. We are small, dedicated and agile. When you ask us a question you will get an answer directly from developers who designed and built AddTapi.NET. And if you need any new features just contact us and we will implement them for you!

Reliable and stable

AddTapi.NET is stable, reliable and trusted by mutli-national corporations and government agenices. Our customers use AddTapi.NET to build computer telephony applications that run 24/7 and handle tens of thousands phone calls per day. AddTapi.NET is even used to manage 911 emergency response call centers!

Just look how easy multi-line Caller ID can be added to your application when you use AddTapi.NET:

Multi-Line Caller ID Using AddTapi.NET

// Initialize AddTapi.NET
// Add event handler for incoming call notifications
TapiApp.IncomingCall += OnIncomingCall;
// Open all available lines to monitor incoming calls
foreach (TapiLine line in TapiApp.Lines)
    line.Open(true, null);

// This method is called when a new incoming call is detected
void OnIncomingCall(object sender, TapiEventArgs args)
    // Display a message to the user
    Console.WriteLine("Incoming call from {0} on line {1}",
        args.Call.CallerID, args.Line.Name);
' Initialize AddTapi.NET
' Add event handler for incoming call notifications
AddHandler TapiApp.IncomingCall, AddressOf OnIncomingCall
' Open all available lines to monitor incoming calls
For Each line As TapiLine In TapiApp.Lines
    line.Open(True, Nothing)

' This method is called when a new incoming call is detected
Private Sub OnIncomingCall(ByVal sender As Object, ByVal args As TapiEventArgs)
    ' Display a message to the user
    Console.WriteLine("Incoming call from {0} on line {1}", _
        args.Call.CallerID, args.Line.Name)
End Sub


Monitor incoming and outgoing calls.

AddTapi.NET monitors incoming and outgoing calls and notifies your application when a new call is received, when a connection to the remote party is established, when a call is disconnected and so on. AddTapi.NET supplies all information needed to develop call monitoring and logging applications.

Answer incoming calls automatically or on request

AddTapi.NET can answer incoming calls automatically after specified number of rings. If you do not need to answer all incoming calls automatically, your application can receive incoming call notifications and decide whether to answer the call or not.

Support multiple lines

AddTapi.NET programming model helps you easily develop scalable applications that work well with any number of lines. You will not believe how easy it is to write multi-line applications with AddTapi.NET until you download the demo version and try it yourself.

Play audio files

AddTapi.NET can play audio files over the phone. AddTapi.NET supports all wave (.wav) files that can be played in Windows, including compressed formats for which the codecs are installed.

Obtain Caller ID and Called ID

AddTapi.NET can obtain caller's name and number on incoming calls. It can also provide called party's name and number if supported by the telephony hardware.

Speak text using TTS (Text-To-Speech) synthesis

AddTapi.NET can "speak" text over the phone using text synthesis. AddTapi.NET supports Microsoft SAPI 5.0 and can use any SAPI-compatible Text-To-Speech engine.

Make outgoing calls

Your application can make outgoing calls using AddTapi.NET. AddTapi.NET detects when a call is answered and reports if there was no answer or the number was busy.

Detect and send DTMF digits

AddTapi.NET can detect DTMF digits on the line allowing you implement touch-tone menus. AddTapi.NET makes it easy to gather a string of digits such as a pin code or an account number. With AddTapi.NET your application can generate DTMF digits to control a PBX or navigate a touch-tone menu.

Record call audio

AddTapi.NET can record audio from phone line to a wave (.wav) file. Other telephony operations such as DTMF detection can be performed while recording is in progress.

Transfer calls

AddTapi.NET can transfer calls to another extension or another number if this feature is supported by your telephony hardware.

Put calls on hold

AddTapi.NET can put calls on hold and retrieve held calls. While the call is on hold the application can use the line to make or answer other calls.

Establish and control conference calls

With AddTapi.NET your application can establish conference calls with 3 or more parties, add additional parties to a conference call and remove participants from a conference call.

Park and unpark calls

AddTapi.NET can park a call and unpark a call parked at the specified extension if this feature is supported by your telephony hardware.

Supports call forwarding

AddTapi.NET can obtain call forwarding information and configure call forwarding for the phone line/extension. Forwarding information describes when incoming calls are forwarded and the destination number(s) for call forwarding.

Detect telephony devices added/removed at runtime

AddTapi.NET detects when a new telephony device is connected or becomes available, allowing your application to work with the device right away without restarting the application. Your application is also notified when a device is removed from the system or becomes unavailable.

Use device-specific features

Many telephony systems provide access to device-specific features using TAPI extensions. With AddTapi.NET you have access to all device-specific functionality provided by the telephony system manufacturer.

Download AddTapi.NET Demo

AddTapi.NET requires .NET Framework version 2.0 - 7.0 and works with all .NET development platforms including Visual Studio 2005-2022, Visual C#, Visual Basic .NET (VB.NET) and Visual C++.

AddTapi.NET has been tested on Windows 11, Windows 10, Windows 8, Windows 7, Windows Vista, Windows XP, Windows Server 2022, Windows Server 2019, Windows Server 2016, Windows Server 2012, Windows Server 2008 and Windows Server 2003.

Fully functional demo version. Demo version run time is limited to 3 hours.

Demo version run time is limited to 3 hours. After 3 hours the demo version stops processing events and the application that uses AddTapi.NET demo has to be restarted to start working again.

AddTapi.NET download includes AddTapi.NET Library, AddTapi.NET Help and C# and VB.NET samples.

Uninstall Instructions

To uninstall AddTapi.NET, open Control Panel, select Uninstall a Program, click on AddTapi.NET in the list then select Uninstall. AddTapi.NET will be removed from your computer.

Order AddTapi.NET

A license is required for each developer who uses AddTapi.NET. Runtime is royalty free. There are no per-server deployment fees.

AddTapi.NET Enterprise (Unlimited lines)

1 Developer License $999    Buy Now!
5 Developer Licenses
(Get 5 licenses for the price of 3)
$2,995    Buy Now!
Site License
(Unlimited developers at one street address)
$9,995    Buy Now!

AddTapi.NET Professional (1-2 lines)

1 Developer License $499    Buy Now!
5 Developer Licenses
(Get 5 licenses for the price of 3)
$1,495    Buy Now!
Site License
(Unlimited developers at one street address)
$4,995    Buy Now!

All prices are in US dollars.

AddTapi.NET Professional is limited to 2 lines per computer/server.

AddTapi.NET Enterprise works with any number of lines supported by the telephony hardware.

60 Day Money Back Guarantee

If you are not satisfied with our product, we will give your money back.

Free updates for one year

All licenses include free updates for one year. After one year new versions are available for purchase at 50% discount. Please contact us to get an update.

Please contact us if you have any questions about ordering.

Licensing Information

Developer and Site Licenses

AddTapi.NET is licensed per developer. A license is required for each developer who will use AddTapi.NET. You are only required to purchase a license for each developer who develops or maintains the portions of your applications which use AddTapi.NET. Site license allows an unlimited number of developers to use AddTapi.NET at one physical street address.

Royalty Free Distribution

The AddTapi.NET license agreement allows you to embed and distribute AddTapi.NET with your application, royalty free. Once you purchase a license for each developer, you may distribute AddTapi.NET with your application without any additional fees.

For detailed information please read the License Agreement.

Authorized Resellers


Outstanding support by experienced programmers

Your AddTapi.NET purchase includes lifetime free basic email support. Premium support subscription is available as well. Please visit AddTapi.NET support page for more information.