Use Walkie-Talkie on Apple Watch
Walkie-Talkie is a fun, simple new way to connect with another user with a compatible Apple Watch. Like using a real walkie-talkie, press a button to talk, and release to listen when you’re ready for them to reply. Walkie-Talkie requires that both participants have connectivity—through a Bluetooth connection to the iPhone, Wi-Fi, or cellular.
Note: Walkie-Talkie is not available in all regions.
Invite a friend to use Walkie-Talkie
Open the Walkie-Talkie app
on your Apple Watch for the first time.Scroll down the list of contacts, then tap a name to send an invitation.
When your contact accepts the invitation, you can start a Walkie-Talkie conversation when both of you are available.
To add another contact, tap 
on the Walkie-Talkie screen, then choose a contact.
Have a Walkie-Talkie conversation
Open the Walkie-Talkie app
on your Apple Watch.Tap your friend’s name.
Touch and hold the Talk button, then speak.
If your friend has made themselves available, Walkie-Talkie opens on their Apple Watch and they’ll hear what you said.
To adjust the volume while you’re talking, turn the Digital Crown.
Talk with a single tap
If you have difficulty keeping your finger pressed on the Talk button, you can use a single tap to talk.
Open the Apple Watch app on your iPhone.
Tap My Watch, go to General > Accessibility, then turn on Tap to Talk.
When this is on, tap once to talk, then tap again when you’re finished talking.
Remove contacts
In the Walkie-Talkie app on your Apple Watch, swipe left on a contact, then tap X.
Make yourself unavailable
Touch and hold the bottom of the screen, then swipe up to open Control Center.
Scroll up, then tap
.
Or, in the Walkie-Talkie app on your Apple Watch, scroll to the top of the screen, then turn off Available.
Turning on theater mode also makes you unavailable for Walkie-Talkie.
For more information, see the Apple Support article Use Walkie-Talkie on your Apple Watch.