Locking an Android phone to a single app (kiosk mode)

First: what is the lock protecting against?

The answer decides which method is enough. If the point is to keep a child inside a game during a bus ride, the simplest option works. If the point is that a person living with dementia should never end up in a browser, in settings or in a banking app, you need something that cannot be tapped out of by accident.

The difference is not sophistication. It is how the phone behaves after a restart, after a system update and after two hundred accidental taps.

1. App pinning — built in, but fragile

Android has a built-in feature called app pinning, under Settings, Security, App pinning. It keeps one app in the foreground until someone actively unpins it.

It does its job, but it was designed for handing your phone to someone for ten minutes — not as a permanent arrangement.

• Has to be switched on manually, and is lost on restart.
• Can be exited with a button combination that is easy to trigger by accident.
• Does not stop the phone dialling or answering the wrong thing.
• Requires someone in the household to know how to turn it back on.

2. Family Link and screen-time tools — they control time, not the interface

Google Family Link and similar tools can block apps and set time limits. They are built for parental control, not for simplifying a phone.

The result is a phone where some things are blocked but the home screen, the notifications and the menus are all still there. For someone who is confused by the interface itself, that solves nothing — and the blocking dialogues can make it harder still.

3. True kiosk mode — the app takes over the phone

Kiosk mode, sometimes called device owner mode, means an app is registered as the phone's owner app. It starts automatically, cannot be exited, cannot be uninstalled without a factory reset, and survives restarts.

It is the same technology used in retail terminals and waiting-room tablets. The catch is that it has to be set up on a wiped phone: an app downloaded afterwards can never take over the device that way, for exactly that security reason.

That is why CallByFace is not on Google Play. The licence is a QR code scanned when the phone boots from factory settings — only then can the screen genuinely be locked.

Turning an Android into a kiosk in practice

The steps are the same whichever kiosk app you use.

• Back up anything worth keeping — the phone gets wiped.
• Remove the previous Google account from the phone, or it will lock itself after the reset.
• Factory reset and stop at the welcome screen.
• Tap the welcome screen six times to open the QR reader.
• Scan the QR code. The phone installs the app and restarts in locked mode.
• Add contacts and photos through the admin menu before handing the phone over.

What you give up with a locked mode

Be honest about this before locking a phone on someone else's behalf. The phone can no longer be used for banking apps, camera, browser or email. There are no notifications from other apps, because there are no other apps.

For someone still using any of that, a locked mode is the wrong tool. For someone who stopped using everything except calling, it is usually exactly what was missing.