TAPI interface

What is the TAPI?

The Microsoft Telephony Application Programming Interface is a interface from the 1990s with which any number of applications are able to communicate with phone systems (telephones respectively) via an unified interface, without having exact knowledge relating to the functions of the connected phones. Microsoft has made a set of uniform functions available, which along with the applications (e.g. Outlook, PhoneSuite CTI Client) as well as the phone system developer (pascom TAPI driver) will need to be implemented.

The pascom VoIP Phone System TAPI driver is in this respect not a stand alone programme, but rather dynamic library (DLL) which is either loaded or unloaded according to requests from the Microsoft-TAPI-Server (Telephony service)

Illustration - Tapi Concept

The pascom TAPI can be installed on all windows workstations. The TAPI registers itself with the server using the same user data as the pascom client. The TAPI is therefore not connected directly to the telephone but rather to the user. Should the TAPI send a dial command to pascom then pascom will automatically search for the current phone being used by the user and uses this to make the call. Should the user change work location or telephone, the TAPI does not need to be reconfigured.

TAPI and the pascom Client

The pascom TAPI can be installed on any windows desktop. The TAPI will then register itself with the server using the same credentials as the pascom Client, which means the TAPI is assigned to a user rather than being directly connected to a telephone. When a dial command is sent to pascom via TAPI, pascom will automatically select the current phone of the user and use this phone to make the call. If the user then changes their location or phone, the TAPI will not require any reconfiguration.

When to use …

.. the pascom Client?

  • When you want a complete overview of your colleagues presence info
  • When you want easy access to faxes and voicemails as well as using chat tools
  • When you have a different OS other than windows

.. the pascom TAPI Driver?

  • When you want to use the telephone functions of your ERP systems, Outlook etc
  • When you want to continue to use your application software with TAPI Support

General Information

Supported TAPI Functions

The TAPI Interface specifies a number of call related functions, of which the following are supported by the pascom TAPI:

Function Comments
Signalization of incoming calls Signaling of phone numbers, call directions, further details
Call Origination Initiate calls to a number
Hang Up End calls
Pickup Complete a pick up on a certain extension
Call Termination Automatically terminate calls on the phone

Support OS versions

Client Server
Windows 7 (32bit/64bit) Windows Server 2008R2 (32bit/64bit)
Windows 8 (32bit/64bit) Windows Server 2012 (32bit/64bit)
Windows 8.1 (32bit/64bit) Windows Server 2012R2 (32bit/64bit)
Windows 10 (32bit/64bit) Windows Server 2016 (64bit)

TAPI Versions

The pascom TAPI requires TAPI version 2.1 to be configured within the corresponding operating system. Programs that utilize the TAPI version 3.X can be used in combination with pascom as TAPI 3.X includes backward compatibility to TAPU 2.X. For more information, please refer to the Microsoft MSDN.


1.Ensure no applications are running which the TAPI Interface uses
2.Ensure that telephony services have been stopped.
3.You can install a debug as well as productive version, in that you can easily repeat the setup. This is also possible vice versa

TAPI Software Download

You can directly download the software by using the Service tab within the pascom Commander login screen:

Screenshot - pascom Service Tab

Please note that there are no separate downloads for 32 and 64 versions of the software. The setup process will automatically identify and install the required files.

Installation on a Windows computer

Administrative privileges are required to execute the setup on a Windows computer. From Windows Vista / 7 upwards, the system will automatically ask for the appropriate login.

Start the setup procedure using the file you just downloaded:

Screenshot - start EXE file

Accept the Terms and Conditions

Screenshot - accept AGB

All the necessary components will now be installed

Screenshot - installing files

After the installation has been successfully completed, you will need to configure the connection of the TAPI to pascom

Screenshot - configure TAPI

As stated before, the TAPI will login with the same user data just like the pascom Client

Variable Description
Username username
Password users´ password
mobydick Server IP number of hostname of the pascom Server

You can now confirm the successful installation by clicking on Finish:

Screenshot - successful setup

Installation on a Terminal Server

Configuration of the pascom

Should you wish to install the TAPI on a Terminal Server or on a computer that is used by more than one person, then you will need assign the users, who will connect using the TAPI, with the xmpp.supervisor Role. This means that only one individual XMPP connection will be constructed from the Terminal Server, over which the total communication will be transmitted.

Screenshot - Successful Installation


The setup requires administrative rights for the corresponding server. From Windows Server 2008 onwards, the system will automatically ask for the appropriate login, however, if you are using Windows Server 2003 you will need to login using the appropriate identifier first.

Start the setup using the previously downloaded file:

Accept the Terms and Conditions:

All the necessary components will now be installed

After the installation has been successfully completed, you will need to configure the connection of the TAPI to pascom

As stated before, the TAPI will login with the same user data just like the pascom Client.

Variable Description
Username username
Password users´ password
mobydick Server IP number or hostname of the pascom Server

Now a further dialogue box will appear, in which you will be able to select the users, who should be available later within TAPI applications (e.g. MS Outlook). All the existing users will be displayed within the list. In order to choose a user, one can double click on the desired user or use the buttons in between the two list screens:

You can now confirm the successful installation by clicking on Finish:

Example scenario with Microsoft Outlook

Start Outlook and select the desired contact entry. Using the right mouse button, select the number to call from the drop down menu:

Now the New Call window will appear: confirm the number by clicking Start call.

Now your telephone should make the call.

On terminal server installations, every user must select their “own” line within the TAPI Software (e.g. MS Outlook), before they will be able to complete a call using their phone.

By clicking Dial Options you can select line to be used:

Unattended (Silent) Installation

It is also possible to install the TAPI without needing any GUI interaction. In order to do this, the installations programme must be called up using the following options:

md-tapi-setup-2.00.00.R.exe /S /options=username:password:server.domain.tld

md-tapi-setup-2.00.00.R.exe /S /options=mmuster:123456789:pascom.example.com

If the TAPI user has the xmpp.supervisor Role, all available users will be automatically selected and will then be available within the TAPI application.

TAPI Debugging

If you uncover a problem when using the TAPI Driver, you can use this manual to start a TRACE, which can then be analyzed by pascom and helping in finding a solution.


In order to record the TAPI debug output, you will need the DebugView tool from Microsoft/Sysinternals which can be downloaded here: https://technet.microsoft.com/en-us/library/bb896647.aspx In addition, it is often also a good idea to record the call construction by using the tool “Tapi Master Line Watcher”( http://www.tapimaster.eu/de/leitungsbeobachter.htm) in parallel to the Debug tool

Please note: Should programme behaviour change as a result of the Line Watch tool, then complete the debugging without it.

Install the pascom TAPI Driver in the Debug-Version

In order to be able to record Debug Output, the debug version of the pascom driver must be installed. Whether you have the productive or debug version installed can be easily identified using the configurations dialog.

  1. Go to the command panel > telephone and modem

  2. Go to the “Advanced” Tab

  3. Select the entry “pascom TAPI Service Provider”

Screenshot - pascom TAPI Service Provider

  1. Click Configure
  2. If in the following mask, the warning “WARNING: DEBUG VERSION INSTALLED” appears, then clearly the Debug-Version is installed

Screenshot - logon tapi

Screenshot logon tapi Debug

Should you still not be certain, then please close all programmes and run the setup again. Please take note of the installation notices and during the installation select, “Debug” and confirm this by clicking next. Screenshot - TAPI installation instructions This will replace any productive versions installed with the Debug version

Preforming a Debugging

You now have all the necessary components downloaded and installed, so start the required tools

Open DebugView

  1. Start the DebugView.exe with Administrator Privileges by right clicking and selecting Run as Administrator Screenshot - open DebugView

  2. Under the “Capture” menu, please check the “Capture Global Win32” option. If you did not run the programme as an administrator, a error message will appear now tap Screenshot - Capture Global Win32

Open Line Watcher

  1. Start the programme - no special permissions required
  2. In the Drop Down under the first tab, select the user´s TAPI Line causing the problems
  3. Check the options box “More information”

Screenshot - Line Watcher öffnen

Next, start your TAPI software and follow those steps which lead to the problem. In the DebugView window, a whole range of tasks should be visible. As long as you start or receive a call information should also appear in Line Watcher Screenshot - open Line Watcher Output

Once the test is finished, save both trace outputs from both applications (DebugView and LineWatcher) Screenshot - TAPI Debug Output View

Saving a DebugView Trace

  1. Click on File > Save as
  2. Give it an appropriate name
  3. Save

Saving a LineWatcher Trace

  1. Click on “Save Message Flow”
  2. Give it an appropriate name
  3. Save

You can now send both files to pascom for analysis.