You can share your Viber screen during audio calls by using the desktop version of the Viber. When you get connected through an audio call, here you get the option of the share screen.
Tap on it and all your screen will be shared via chat box to your fellow. This feature is active only on the Desktop version. It is not available in the phone version.
While using the Viber on desktop you can share any screen and file. It makes communication easy and you can resolve problems on your computer conveniently.