Block all without viber

Hello,

I want to block all website (http and https) but only open viber on mobile/pc.
So please someone advise me, how I can block all, except viber.

Regards,
Nishadul

Then the user would just use facetime/facebook, whatapp, skype, lync or other app that you can do video/talk trough internet.
It looks like it uses https, its it will be hard to block.

Here is a thread with same question:
http://forum.mikrotik.com/t/how-to-block-viber/80166/1