I have this question too. Can i switch off or have to uninstall totally from my phone? Since i am using whatsapp, it sufficient for me already. And viber call quality highly depend on both user line quality and stability, which in Msia is quite hard. I want to switch on when i am on wifi only.

i asked this before.. settings page, uncheck display notification icon.. and yes... since it's a background running app instead of push messages, it WILL drain batt life despite what they say in their official website.... not that i believe advertisements like that always also...