The Viber Chat is missing a very simple but important feature. It only supports phone numbers, but not bot URLs. Bots can be created at: partners.viber.com
Here's the difference. The URL format for a phone number viber link is:
viber://chat?number=+{PHONE-NUMBER}
The URL format for a viber bot link is:
viber://pa/info?uri={BOT-USERNAME}
It'd be super easy to implement ;) Would that be a possible feature added in the near future?