Are calls on Whatsapp/FB/Zoom over cellular network made on IMS protocol?

Not sure even if my question makes sense or not. I am new to the IMS framework and just want to learn its utilisation.

My understanding of it is that the Internet services (like browsing, or watching YouTube videos etc.) is a different ball game, whereas IMS only provide services like VoIPs, and Internet callings (like Zoom, Whatsapp, Skype etc.)