tl;dr: Apple's Assistive Access mode (buried in Settings > Accessibility, introduced in iOS 17 for users with cognitive disabilities) can transform an old iPhone into a customizable "dumb phone" for kids, with large-tile UI, whitelisted apps, and—unlike Screen Time restrictions—a hard block on web browsing that can't be bypassed via messaged links. The author configured his son's iPhone 13 with just Calls, Messages, Maps, Camera, Photos, and Music, retaining Find My tracking without monthly fees. Downsides: it runs sluggishly, disables voicemail, prevents powering off, and occasionally freezes (e.g., in Messages emoji search).