You probably already know the Apple Watch is great at making phone calls. It’s still something of a secret, though, that you can unleash your inner Dick Tracy by using the Apple Watch as a walkie-talkie. As long as the person on the other line has you as a contact in their Apple Watch’s Walkie Talkie app and has watchOS 5 installed, you can immediately contact them with a real-time voice message regardless of where they are or what they’re doing.

In the wrong hands, of course, this could be maddening. Fortunately, Apple makes it easy to turn the feature on or off, and it’s also easy to get rid of contacts who abuse it. You can also add a complication for easier access.

It’s gimmicky, sure, but Walkie-Talkie does have its uses. On a recent hiking trip, for instance, a friend and I used it to send each other updates after we split up to look for his missing wallet. It beat both calling and texting for by-the-second convenience. I imagine all such uses are that specific (although I could also see parents using it to keep track of kids in an amusement park), but even so, it’s a welcome option in an ecosystem that’s resistant to options.

Here’s how to use it. You don’t have to worry about installing it: if you have watchOS 5, it should already be there.

I had to restart my Apple Watch for Michael’s name to show up after I entered it in my contacts.

If you’re on the other end, you’ll receive a notification saying that a contact “wants to talk with you over Walkie-Talkie.” Press Always Allow to agree—sorry, there’s no middle ground—or Dismiss to decline (or at least put it off.)

Or does he?

If the user on the other end isn’t wearing their Apple Watch or has their contact preference set to Unavailable, you’ll only see the app trying to connect with them, followed shortly by a notice that the person is unavailable.

There is no true “hands-free” mode, unfortunately.

Even if you find Walkie-Talkie useful, you’ll want to disable it on occasion. You might be in a movie theater, for instance, or an important meeting. Apple Watch makes it easy.

Alternatively, you can simply turn on Theater Mode or Do Not Disturb Mode through your Apple Watch’s Control Center. Keep in mind, though, that Silent Mode doesn’t affect Walkie-Talkie, so you’ll still hear dings for incoming calls as well as the voice of the person on the other end.

It’s probably wise to keep this off most of the time.

X marks the spot.

If someone doesn’t respond to your Walkie-Talkie invitation, the invite loiters around until you dismiss it. Annoyingly, these invitations tend to stack on top of the contacts you can already interact with. Fortunately, it’s easy to make them go away.

The nerve!

This story, "How to use the Walkie-Talkie app on Apple Watch" was originally published by Macworld.