You probably know it's good practice to have a password, PIN number, or fingerprint check protecting your phone. Otherwise any stranger, relative, or work colleague can simply pick it up and start playing around with your banking apps, email account, and perhaps even more worryingly, your social media apps.
The lock screen on iOS and Android blocks access to all of this personal information, but it can still reveal more than you might think. That's because Google and Apple have tweaked the lock screen to allow easy access to some of your phone's main features, including Siri and the camera app. Here we'll explain what can be accessed, and how to adjust the lock screen settings to make it a better barrier.
There is a balance to strike though. Having some shortcuts on the lock screen adds an extra level of convenience for you. And if you lose your phone, you'll want to leave some clues for whoever finds it so it can be returned to you. We'll explain how you can do that as well.
Lock screen settings for iOS
Siri has become more and more important for iOS since her introduction back in 2011, and so by default, Apple lets you launch the program straight from the lock screen with a "hey Siri" command. This is fine if you want to check the weather or look something up on Wikipedia without unlocking your phone. But, while the lock screen blocks a lot of common Siri commands—relating to messages, emails, and other private information—there are some potentially problematic requests that still work.
You (or anyone else) can ask Siri, "What's my name?" to see a phone owner's name and mobile number, or "Who do I call most?" to see a list of recent calls. Presumably Apple leaves these options open so that, if someone picks up your phone, they can try and get it back to you. In practice, however, this allows a complete stranger to access your locked phone and discover who you are, where you live, and even where you've parked your car. If you'd prefer to protect this information, then head to the Siri menu in Settings and toggle the Access When Locked switch to off.
Even without Siri, you can still give strangers who find your phone a chance to return it. Head to the Health app that comes as part of iOS. Tap Medical ID, then Create Medical ID, and you can specify someone in your address book as an emergency contact. This info can be accessed from the emergency dialer part of the lock screen. It's useful if you're caught up in a medical emergency, as well as those times when you've just left your phone on the bus.
In addition to Siri, anyone can launch a phone's camera from the lock screen too, with just a swipe to the left. It's not possible to go back through old photos, but someone could take new pictures. The only way to prevent this is to disable the camera completely, via the Restrictions menu under General in Settings—so it's your call.
There are a few more settings to be aware of, which you'll find under the Touch ID & Passcode menu in Settings. From here you can enable or disable the Today View (news summaries, weather reports), the Notifications View, Siri, Apple Wallet, and Reply with Message, which could potentially let anyone instantly reply to a message without unlocking your iPhone's screen.
Lock screen settings for Android
Over on Google-powered phones, the options are pretty similar, but also differ in the details. With so many versions of Android around, it's not as easy to provide definitive instructions, but these apply to the latest (7.0+) version of stock Android. You should be able to adapt them to your own phone without too much trouble.
By default, the Android lock screen doesn't let you access any kind of private information. While you can launch Google Now or the Google Assistant, no answers will be given until you unlock your phone using a PIN code, fingerprint, or whatever other method you've set up.
Android will let you get past your lock screen with voice alone, but it must be your voice. To enable this ability, go to Security in Settings and tap Smart Lock, then choose Trusted voice. Obviously, this won't work for anyone else who isn't you.
You can launch the camera from the lock screen without any verification, although, as on iOS, access to the photo and video library is blocked. There's also no way to turn this off on the lock screen, so you just have to live with it—enjoy the extra convenience you get from quick access to the camera, even if your friends can fill up your phone with selfies whenever your back is turned.
One option you can change relates to notifications that appear on the lock screen. If you don't want anyone to see potentially revealing information, go to Settings, choose Notifications, and tap on the cog icon. Here you can choose to block lock screen alerts completely or just restrict "sensitive" ones (typically notifications from messaging apps). You can also disable notifications on an app-by-app basis from the Notifications menu.
Finally, Android also has a way to leave some contact information on the lock screen for those who might find your phone and want to return it. From Settings, tap Users then Emergency information. Here you can add any of your own info (name, address, blood type) as well as one or more contacts from your address book. As on iOS, these details are accessible to anyone from the emergency dialer part of the lock screen. To leave a simpler, one-line lock screen message, go to Settings, Security, and tap the cog icon next to Screen lock.