I'm even more intrigued by the whole family sharing two phones and switching sim cards. What's the reason behind it? How does it work?
Probably practicing minimalism
It's vanishingly rare for me. I got a call from a friend today - but I think I otherwise only make or receive a legit phone call every few days. We use social media mostly. Work "calls" are on apps.
A family could probably get away with 2 phones easily, as long as they have home internet.
Now... When I was young and internet was over dial-up, having a single phone line for our whole family caused quite a lot of spats.