I didn't know twitter had calls at all. Is this a popular feature for paying users? How do people use it/what do people use it for? What do twitter want people

I didn't know twitter had calls at all. Is this a popular feature for paying users? How do people use it/what do people use it for? What do twitter want people to use it for (beyond 'give us more data')? Allowing calls from anyone sounds like a bad time lol From someone who doesn't use twitter it sounds like a really weird thing to try jam into a short-form social platform? If anyone does have any insight (beyond the clearly terrible direction of twitter) I'm curious