Ever wondered why it's not possible to dial a phone call from a Windows application using your VoIP Account? So did we, and we solved the problem: Download and install SIPTAPI to initiate calls from your favorite TAPI application (e.g. MS Outlook or CRM applications).

Problems with SIPTAPI? -->SIPTAPI FAQs

Do you need support? --> SIPTAPI Support


SIPTAPI is a TAPI Service Provider (TSP) for MS Windows. SIPTAPI enables you to initiate phone calls from TAPI applications (like MS Outlook) via your SIP PBX or with common SIP VoIP phones.

SIPTAPI itself is not a complete SIP phone, but acts as a "3rd Party Call Controller" on your SIP devices, instructing them to call the desired phone number. See the following figure for details:

SIPTAPI Versions

SIPTAPI comes in 2 flavors, either as "free" or as "commercial" version. The free version supports a single line only. The commercial version supports multiple lines and thus is suitable for Windows terminal servers. Furthermore, the commercial version supports inbound call indication.

Number of SIP lines140+
Support for terminal serverneinja
Inbound call indicationneinja
Source code & project filesjaja
Screenshot of the configuration dialogScreenshotScreenshot

You can download the free SIPTAPI from the Sourceforge project website (see link on top of this page). Please contact us for information about the commercial SIPTAPI.


Supported operating systems (32bit and 64bit):

  • Windows 2000
  • Windows XP
  • Windows Vista
  • Windows 7
  • Windows Server 2003
  • Windows Server 2008

SIPTAPI should be compatible with every SIP-conform device that supports call transfers (REFER method). SIPTAPI is sucessfully tested with:

SIPTAPI should be compatible with every TAPI application. SIPTAPI is known to work with:

Documentation and Support

SIPTAPI comes with an installation manual and a tutorial which describes the details of SIPTAPI.

See SIPTAPI Support for details how to debug your problems.

Integration with Proprietary Systems

The SIPTAPI software is not a complete TAPI application - SIPTAPI is only a "TAPI provider". To use the Windows telephony features you also need a "TAPI application" which uses the TAPI providers to initiate calls. The most simple and universal available TAPI application is "Phone Dialer" (dialer.exe) which comes with Windows. Another worth mentioning TAPI application is the freeware "Phoner" (do not confuse with Phoner Lite). Phoner is especially useful for testing purposes as it is used for SIPTAPI testing. Using Phoner you can find out if the problems are within SIPTAPI or your proprietary TAPI application.

If your CRM application supports TAPI natively, there is no need for an explicit TAPI application.

But if your CRM application does not support TAPI, or for example you use a web-based CRM application, there is another useful tool: dial.exe. dial.exe is a small command line utility which initiates phone calls using the default TAPI dialer (usually dialer.exe). dial.exe can be integrated via the command line or via the callto: and sip: URL handler. Note: dial.exe can not be used on Windows terminal servers (Citrix).


SIPTAPI is open source, licensed under GPL version 2.


SIPTAPI is open source. Thus, feel free to download the source code and add new features yourself. The source code is hosted in the SVN Repository at Sourceforge.

Please see SIPTAPI.txt how to build SIPTAPI yourself.

If you need extensions for SIPTAPI but do not have the time or resources yourself we're happy to implement your feature requests time & material basis. For further information and pricing, please contact klaus.darilion (at) with a description of the required work.