If you’re buying a used phone, there’s always been one critical thing to look out for: whether the device is stolen. And finding that out is getting a bit easier today. The US wireless industry, through its trade group the CTIA, has launched a tool called the Stolen Phone Checker, which lets you look up whether a phone has been reported lost or stolen.

The site works by looking up a device’s IMEI, MEID, or ESN — unique codes that get assigned to every phone. These are sometimes printed on the back of phones, like the iPhone, but in other cases they can be found somewhere deep in the settings menu.

Stolen phones won’t be able to get service

Checking this out before buying a used phone is important for a handful of reasons. But perhaps the simplest is that if the phone you get turns out to be lost or stolen, it pretty much won’t work. For several years now, US phone carriers have kept a shared database of stolen phone IDs, and they won’t allow those devices to be connected to their network.

The CTIA’s tool isn’t the first of its kind. There are a handful of third-party lookup tools out there — like this one from Swappa — and the big carriers have their own, too. But it sounds like the Stolen Phone Checker is being positioned as the canonical site for looking these things up. And if nothing else, it has the easiest name to remember. So if you’re buying a device off Craigslist, eBay, or some other used phone dealer, be sure to check one of these sites first.