I've set up voip instances, and not liked it, but would be willing to do it again for my kid. I'd not be willing to set them up (and be tech support!) for all of his friends' families. That's the value proposition here, for me.

We've got a group of parents around us who'd likewise like to delay their kids' smartphone access for as long as possible - but if a smartphone (or even a dumbphone with no meaningful parental controls) is the only way for kiddo to make calls, then I know some of them will defect. Selling them all on this kit (or something like it) would keep the agreement intact for a while longer.