AddTapi.NET 5.0 is available

New version 5.0 of our computer telephony library AddTapi.NET is available for download from To upgrade the purchased version of AddTapi.NET please send your serial number to Here is a list of new features in AddTapi.NET 5.0:

Conference call support

AddTapi.NET 5.0 adds support for conference calls with three or more parties. The application can use TapiLine.SetupConference or TapiCall.CompleteTransfer resolved as a 3-way conference to setup a conference call. Additional parties can be added to the conference using TapiCall.PrepareAddToConference and TapiCall.AddToConference methods.

Audio playback and text-to-speech in Windows service applications

This version includes new audio engine that supports audio playback and text-to-speech in applications that run as a service. With AddTapi.NET 5.0 you can develop Windows services that play .wav files and speak to the callers using text-to-speech. Both TapiCall.Play and TapiCall.Speak can be used in Windows service applications without any problems.

Line device state information

New version adds TapiApp.LineDeviceState event that fires when the state of the line device changes. The application can use this event to find out when the line goes out-of-service and back in-service (TapiLineDeviceStatus.IsInService property), when the line is connected/disconnected to TAPI (TapiLineDeviceStatus.IsConnected property) or when the message waiting indicator turns on/off (TapiLineDeviceStatus.IsMsgWaitOn property).

Device-specific information about the line status

Version 5.0 adds TapiLineDeviceStatus.DeviceSpecificInfo property to obtain device-specific information about the line status. Avaya IP Office system uses this property to provide a lot of additional information about the line/extension, including call forwarding/DND information, number of read/new voicemail messages, user login information and much more. Please contact us for more information and we will provide a code sample that shows how to use this feature of the Avaya IP Office phone system.

Separate assemblies for .NET 4.x and .NET 2.0/3.x

Starting from version 5.0, AddTapi.NET assemblies located in the installation folder are compiled for .NET 4.0 and will not work with earlier versions of .NET Framework. If your application is targeting .NET 2.0 or 3.x, please reference Traysoft.AddTapi.dll located in the NET2 folder of your AddTapi.NET installation.

Other small fixes and improvements

– Incoming calls were reported as outgoing on some phone systems with non-standard TAPI drivers.

– Implemented a workaround for outgoing calls on Tadiran Coral IP PBX. The TAPI driver for the Coral system does not list any addresses that support outgoing calls and AddTapi was showing an error.

– Version 5.0 uses 8kHz 16-bit audio format on Avaya IP Office for better audio quality.

TapiApp.OutgoingCall event was not fired when establishing dial-up connection.

Published by

Michael Rakita

I am the founder and CEO of Traysoft Inc. I also design and develop software, provide customer support, manage our websites and do everything else including posting on this blog :-)

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