It’s surprising how a lot of smartphone users don’t know their devices have built-in trackers. I used to be one of those people, too paranoid to turn on location services, clueless it can be tweaked per app.

Until I lost an iPhone 4s to pickpockets and could do nothing about it.

What rubbed salt in the wound was the knowledge that I could have, had I simply prepared the correct settings on my phone beforehand.

For iPhones running the latest iOS, just turn on the Find my iPhone app under the iCloud settings, and download the free apps. From there, you can use your Apple ID to track your device on iCloud.com.

The feature has already proven useful to me. Recently, someone made the mistake of taking my second iPhone, then simply trying to deny it. We found some pretext for him to move, monitored, to another street.

The tracker, which I logged onto from my laptop and from a friend’s phone, clearly followed his change of location. He was left with no choice but to fess up and return the phone.

The tracker gets as specific as up to a building on a street on Google Maps. With that, you can soon single out a thief on the move.

On iCloud.com, you can also remotely play a sound on your phone, even when it’s been placed on silent. Triggering Lost Mode, meanwhile, will allow you to see not only the current location of the phone, but the route it passed to get there.

It will also allow you to display, on the phone, a contact number and a message. What that message will be—pleadings or threats—is up to you.

Some Samsung smartphones have similar locators. After signing up for a Samsung account, tweak your security settings to turn on the Remote Control. Use the Samsung account to log on to Samsungdive.com, and track, ring, leave a message on, or lock your phone from there.

I tried it on a Galaxy S3, and found you can even set a call forwarding number from online.

I haven’t tried Blackberry phones, but a quick online search shows they also have a similar app called Blackberry Protect.

Sadly, I found that once the phone is turned off, and without cellular data or Internet connection, the tracker shuts down.

So once you discover your smartphone is missing, act fast.

But I wouldn’t advise you to go after thieves or robbers. Enlist the help of police or security guards quickly, highlighting that your stolen device has a tracker. With such a solid lead, they’re more likely to act.

If you decide to give up the phone for lost, you can wipe it remotely online, too. But call your network to have the phone deactivated completely.

Of course, the best preparation is still simple precaution and presence of mind. A smart person trumps a smartphone any day. As much as possible, keep your devices hidden and close to you.

Under threat, just hand the device over. Keep your wits about you when you report the crime to the nearest police precinct. Describe the perpetrators as accurately as you can. Log on to the tracker from there.

And if you’re brave or desperate enough: Go sic ’em.