Does virtual sim still require an underlying physical sim (to provide cellular data) or WiFi access?

Question

I am a bit confused on the concept of virtual sim as explained in this Quora post. My current understanding is that a virtual sim relies on a cell phone app to generate virtual phone numbers. But typically cell phones will need to connect to the Internet to communicate information with some remote service, right? So does this mean that a cell phone running a virtual sim still requires either WiFi access or a physical sim that provides cellular data access?