So I installed Viber on my Ubuntu 14.04 and had the realisation that the notification icon was at the wrong place (top left instead of with the other icons on the tray).
I followed the instructions at Annoying Viber notification and installed the viber indicator program. This was working fine for a while, but at some point (possibly after updates) viber indicator can no longer launch. I tried re-installing it but is still refuses to launch. I can still launch Viber normally but that doesn't help because the indicator is again at the wrong position.
For anyone who may run into this in the future, as of (possibly) version 6 of the Linux client for Viber, the notification is behaving correctly without the need of any other packages to be installed.