A few years back, reports of thieves taking selfies with stolen iPhones were commonplace. Now smartphones come with lockout features and encryption tools that give their owners control over the device from afar. This includes the power to wipe the phone of all data, keeping it safe from thieves or whoever picks up your lost device.

What you may not realize is that these “remote wipe” software services usually require you to activate the feature. Here’s how.

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If you own an Apple iPhone:

● Go to Find My Phone and set up an account for each device using your Apple ID. This feature requires you to activate iCloud, Apple’s online backup service for photos and other data.

● Once you have iCloud set up, you’ll be able to monitor each device in this online account. If you wind up needing to erase all the phone’s data, you’ll head here. Before getting rid of the data, you can enter your phone number and a message, which will be displayed on the erased device’s screen. You decide what the message will say.

● Before erasing the phone, make sure it’s actually stolen and not just sitting next to your locker at the gym. Try to find your phone by playing a sound or locating it on a map. If you’re lucky, the guy on the spin bike you were using an hour ago will hear your phone ringing while you’re simultaneously seeing your gym come up on the map.

● If your phone is lost, tell your mobile service provider so you can avoid any unexpected charges.

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If you own an Android phone:

● Open the Google Settings application on the phone. (This is not the same as the general Settings application for the phone itself.)

● From Google Settings, turn on Android Device Manager. Check off the boxes that allow you to remotely locate the device, remote lock and erase.

● The Device Manager icon will pop up. You’ll see a map indicating where your phone is (most likely, it will say “In your hand”) and options to ring the phone, locate it or erase it.

● If your phone is running Android 4.1 or higher, turn on location access. It’s in Google Settings under Location. This is handy if you want to use one Android device to find another device, perhaps a tablet you own. If your phone is indeed lost, go to www.android.com/devicemanager on any web browser and log in to your Google account. The device manager will locate your phone on a map, make it ring loudly for five minutes or allow you to erase it remotely.

How to wipe other phones:

● To remotely wipe a Windows phone, log into your Microsoft account at www.windowsphone.com and click Find My Phone in the upper-right corner. From there, it’s fairly easy to ring, lock or erase your phone.

● BlackBerry devices are often managed by corporate IT directors. If you lose a BlackBerry, it’s best to immediately report the loss to your employer and allow them to manage the process.

Related: Your Email Got Hacked — Now What?

Greg writes about personal finance, business and technology. His work has appeared in Businessweek, Newsweek, Forbes, Bankrate and a variety of trade ​publications.