Unter Linux sagt er das folgende, vielleicht hilft das ja und es ist möglicherweise unter Windows das gleiche. Ist IMHO ein Lücke in der Dokumentation, da sollte das stehen.
Options:
--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
options.
--exec Execute a command instead of starting a
client instance. Example: --exec dial,*104
(Calls your own Voicemailbox)
--onlySoftphone Run only softphone without client
--noUpdate Disable automatic update. Via Environment:
Set PC_NO_UPDATE to any value.
--forceTouchMode Show UI like touchscreen is enabled
--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.
--logXmppMessages Log complete Xmpp Messages. Via
Environment: Set PC_LOG_XMPP_MESSAGES to
any value.
--logMessageNames Log Message Names. Via Environment: Set
PC_LOG_MESSAGE_NAMES to any value.
--disableHeadsetSupport Set to true to disable automatic headset
detection and controls. Via Environment:
Set PC_HEADSET_SUPPORT_DISABLED to any
value.
--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.
--loglevel <loglevel> Set Logging verbosity. values from 0-5.
Via Environment: Set PC_LOG_LEVEL to
desired 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
value
--minimized Do not open the main window on startup.
Via Environment: Set PC_MINIMIZED to any
value
--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.