Dark Mode is a display setting that uses light text and icons on a dark background. 

The OnSIP App now has Dark, Light, and Use System options. This can be changed by the indicator near the top right of the screen. Dark and Light Mode have the same functions, features and capabilities.  The only difference is the color scheme.

When Dark Mode is set the indicator will change from the sun to the moon and the background will change to black.

If you choose Use System, this will use the same setting that your device is set to.