As soon as your calls makes it to a cell tower it gets encapsulated and routed over a telco’s network. Any call you make from one call provider to another will traverse the internet. And depending on the extent of the thought experiment for disabling the internet, you could include disabling individual telco’s networks as well, meaning you won’t be calling anyone… except for maybe someone on the same tower as you.
People generally use apps and such, but as far as I’m aware most phones still come with a phone number these days
What’s your point?
As soon as your calls makes it to a cell tower it gets encapsulated and routed over a telco’s network. Any call you make from one call provider to another will traverse the internet. And depending on the extent of the thought experiment for disabling the internet, you could include disabling individual telco’s networks as well, meaning you won’t be calling anyone… except for maybe someone on the same tower as you.