Viber doesn't ring when screen is locked

[WPCentral Question]

I have Lumia 630, software Lumia Cyan WP 8.1

Viber rings only when app is opened. When I exit app or lock the screen, Viber goes offline. What should I do? I tried to reinstall, but its still the same.

 

[vaib04]

go to battery saver ->usage
select viber and allow always