I've never owned a smart phone but sometimes I power off my flip-phone. When I was working I would set the default ring tone to a nearly silent beep then set a

I've never owned a smart phone but sometimes I power off my flip-phone. When I was working I would set the default ring tone to a nearly silent beep then set a custom ring tone for work and the paging system they used. I have no idea if WhatsApp supports this but if you could set custom tones per person or groups of people then you could minimize distraction. If your phone supports it you could also have it mute all sounds during certain hours.