> an old-school landline phone connected to a VoIP box, served by UniFi Talk ($10/month).

That sounds interesting, going to look into it. My son is old enough to be home alone but I don’t want to get him a cell phone yet, but I don’t want to leave him alone without a phone in case of an emergency. Traditional home phone plans from the usual telecoms are way more expensive than I thought they’d be.

What should I be looking for with regards to a VoIP box? Not even sure what to search for specifically,

> What should I be looking for with regards to a VoIP box?

I just bought the one from Ubiquiti. No fuss, works out of the box: https://store.ui.com/us/en/category/managed-voip/products/ut..., though you do need a separate piece of hardware on which to run the UniFi talk app. For me, that was my UniFi gateway (UXG-Max) - I have a lot of UniFi equipment.

There are others that could work - you can look up UniFi Talk supported devices.