Desktop Client Installation

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How to install the pascom desktop UC client on Windows, macOS and Linux.

Modify Your Firewall

Many companies do not have any Internet access restrictions and can therefore immediately start using the [pascom desktop UCC client}( “pascom Desktop Mobile Unified Communications”) without needing to make any alterations to their Firewall.

However, should you choose to, you can specify which internet services your company network is permitted to access by opening the following ports and allowing the pascom desktop client access in order to ensure that your pascom phone system operates optimally:

Configure Firewall / Port Overview

Windows Installation

System requirements: Windows 8.1, 10 or 11 (64bit) including the most up-to-date patch levels.

The Windows installation process does not require any admin privileges and be performed directly in the home-directory of the currently logged in user:

Windows QoS Settings (Optional)

In order to achieve the maximum voice quality, the pascom client marks all voice data accordingly with QoS flags.

With the exception of Windows, this happens automatically on all other platforms.

The following group policies “Policy-based QoS” are required under Windows to mark the packages accordingly.

The group policies are created under the following path:

Local Computer Policy > Computer Configuration 
> Windows Settings > Policy-based QoS
Policy 1 Policy 2 Policy 3
Policy Name pascomSIP pascomRTP pascomXMPP
 Application Name  pascom Client.exe   pascom Client.exe  pascom Client.exe
 Protocoll  TCP and UDP   UDP  TCP
 Source Port  *   *  *
 Destination Port    5060:5062   30000:35000  5222
 Source-IP    *    *  *
 Destination-IP  *   *  *
 DSCP Value  24   46   24
 Throttle Rate  -1   -1  -1

Terminalserver Installation

System requirements: Windows Server 2008 R2 64bit or higher

When using this installation method, the automatic pascom desktop client updates will be deactivated, even without setting the noUpdate command line option. You will need to download and deploy the newer clients versions manually.

(Optional) On the Microsoft Terminal Server it is possible to install the pascom desktop client directly in the programmes directory instead of the corresponding user’s home directory.

The disadvantage of this type of installation is that you will need to manually perform all pascom desktop client updates, as the updates require admin rights. The advantage of terminal server installations is that you can save upto ca. 100MB storage space per user.

  • Download the Windows Desktop Client
  • Open the command prompt as an Administrator
  • Start the setup and specify the install directory


pascomClient-setup.exe /D=C:\Program Files (x86)\pascom Client

Use RDP Split Mode on Terminal Server


Using the command line parameter --rdp or by setting the environment variable PC_RDP to 1 it is now possible to disable softphone and video support for the client on the Terminal Server. This allows the client on the Terminal Server to use the softphone of another client instance for telephony.

This allows e.g. to start one client instance within an RDP session and another one on the host computer. The instance running within the RDP session has the --rdp flag set, the outer one does not. Thus, a headset connected to the PC can be used for telephony.

What does this do?

  • Better audio quality, as the audio does not have to be transferred to the RDP session
  • Headset control (e.g. Accept via button on headset) works as a result.
  • Integrations in software running on a terminal server (e.g. Outlook, DATEV) still works.
  • Less CPU load on terminal servers, since audio and video are encoded and decoded via the client on the respective terminal device.
  • Call control is fully possible via each of the clients.

The feature works across platforms (Windows, macOS, Linux) and is not limited to RDP sessions.

Mac OS

System requirements: macOS High Sierra 10.13 or higher

  • Download macOS Desktop Client
  • Run the pascom Client.dmg file
  • Drag the pascom icon (red) on to the Applications folder
  • As soon as the copy process has been completed, you will be able to start the client

Installation on MAC with Apple M1 Silicon CPU

As soon as you want to install the pascom client on a MAC with Apple M1 Silicon chipset, the installer will ask you to install the Rosetta 2 program. This program ensures that you can use applications designed for a Mac with Intel processor.

Linux Installation

System requirements Ubuntu 18.04 LTS or higher. Other Linux distributions may work, but are however neither tested nor officially supported by pascom.

  • Download the Linux Desktop Client
  • Unzip pascom_Client.tar.bz2 in the home directoy
  • Create Ubuntu Application Icon with
  • Start the client via the Application Icon


tar jxvf ./Downloads/pascom_Client-7.17.10.R.tar.bz2

Windows Installer Command Line Parameters

Parameter Explanations
S Enables an installation in to run in the background, without displaying any dialog windows.
D=PATH Enables the defining of the installation folder, i.e path. This parameter must always be the last parameter in the command line and only supports absolute file paths

Desktop Client Environment Variables and Command Line Options

The pascom Desktop Client supports a range of command line options and reacts to a nummber of environment variables on all operating systems.

Using the --help parameter for more information on which options and envirnoment variables are supported by your version of the pascom desktop client.


- PC_SCALE_FACTOR=<value>: Set this environment variable to override automatic DPI Scaling value. Useful if you have a Setup with multiple Monitors and non-integer scaling factors. Value is a real, e. g. 1, 0.75, 1.5, and applies as second factor to the Scaling Value QT Calculated. Example: Your screen is at 150% scaling, QT would calculate a factor of 2. So VALUE needs to be 0.75 to get to the correct real scaling of 1.5

- PC_SCENE_GRAPH_BACKEND=<value>: Set this environment variable to switch the backend used for rendering the ui. Useful if the default backend produces graphic errors on your setup. Do not set or leave empty to use automatic (Software on Windows, OpenGL on other platforms). Possible Values are: software, d3d12, openvg, opengl

- PC_QSG_RENDER_LOOP=<VALUE>: Change the used opengl render loop by setting `QSG_RENDER_LOOP` internally. Defaults to 'basic' if not set. Possible Values are: basic, windows, threaded


  --userDir <userDir>                Set user directory. Via Environment: Set
                                     PC_USERDIR to desired value
  -h, --help                         Displays help on commandline options.
  --help-all                         Displays help including Qt specific
  --exec                             Execute a command instead of starting a
                                     client instance. Example: --exec dial,*104
                                     (Calls your own Voicemailbox)
  --noUpdate                         Disable automatic update. Via Environment:
                                     Set PC_NO_UPDATE to any value.
  --forceTouchMode                   Show UI like touchscreen is enabled
  --debugMode                        Debug Mode. Via Environment: Set
                                     PC_DEBUGMODE to any value.
  --pcRendererMode <pcRendererMode>  Change the used rendering backend.
                                     Possible Values are: opengl,
                                     openglSoftware, software. On Windows there
                                     are addition modes: angle, angleD3D9,
                                     angleD3D11, angleWarp. Via Environment: Set
                                     PC_RENDERER_MODE to desired value.
  --rdp                              Disable all video and/or audio
                                     functionality on this client instance. Via
                                     Environment: Set PC_RDP to any value
  --disableHeadsetSupport            Set to true to disable automatic headset
                                     detection and controls. Via Environment:
                                     Set PC_HEADSET_SUPPORT_DISABLED to any
  --logSennheiserMessages            Log all communication from and to
                                     Sennheiser HeadSetupApplication. Via
                                     Environment: Set PC_LOG_SENNHEISER_MESSAGES
                                     to any value.
  --logPolyMessages                  Log all communication from and to Poly /
                                     Plantronics Hub Application. Via
                                     Environment: Set PC_LOG_POLY_MESSAGES to
                                     any value.
  --useCustomNotificationsAsDefault  Do not use native notifications by
                                     default. Via Environment: Set
                                     PC_USE_CUSTOM_NOTIFICATIONS_AS_DEFAULT to
                                     any value.
  --iceServers                       STUN/TURN Servers to use, comma separated.
                                     Via Environment: Set PC_ICE_SERVERS to
                                     desired value.
  --disableVideo                     Completely disable video support. Via
                                     Environment: Set PC_DISABLE_VIDEO to any
  --user <user>                      Override login username. Via Environment:
                                     Set PC_USER to desired value.
  --password <password>              Override login password. Insecure, please
                                     use PC_PASS environment variable instead
  --server <server>                  Override login server. Via Environment:
                                     Set PC_SERVER to desired value.
  --minimized                        Do not open the main window on startup.
                                     Via Environment: Set PC_MINIMIZED to any