If you set up cellular
If your iPhone and Apple Watch Series 4 (GPS + Cellular) or Apple Watch Series 3 (GPS + Cellular) are both connected to a cellular network, your watch can do everything that it normally does, even if your iPhone isn't with you.1 When your watch connects to a cellular network, 
appears in Control Center.
If your watch is connected to a cellular network, but your iPhone isn't nearby, your watch can do the same things that it can when using Wi-Fi.
If you have a Wi-Fi connection
When your iPhone is off or out of range, your Apple Watch can use Wi-Fi networks. When you connect to one of these Wi-Fi networks, 
appears in Control Center. You can still do these things.
Use Siri to get directions, send iMessages, and more.
Send and receive messages.1
Make and receive phone calls.2
Check the current weather.
Track your stocks.
Control your home.
Use apps that support Wi-Fi.1
Set reminders.
Listen to podcasts.
Stream music.
Listen to the radio.
If you can't connect to Wi-Fi, cellular, or your iPhone
When your Apple Watch is disconnected, you can still do these things. For example, you might be hiking in an area without Wi-Fi or cellular signal or your iPhone might be off.
Track your workouts with the Workout app.3
Track your goals with the Activity app.
See the time and use the Alarm, Timer, and Stopwatch apps.
Display photos from synced photo albums.
Make purchases with Apple Pay.
Check your heart rate.
Relax and breathe mindfully.
Listen to podcasts stored on your Apple Watch.
- To receive SMS from third-party apps, MMS from third-party apps, or push notifications from third-party apps on your cellular model of Apple Watch, your paired iPhone must be powered on and connected to Wi-Fi or cellular, but it doesn't need to be nearby. You also need to be signed in to iMessage on your iPhone.
- If you're on Wi-Fi and want to call a phone number, make sure that Wi-Fi calling is turned on for your Apple Watch. Otherwise, try making a FaceTime audio call.
- For GPS accuracy when you walk, run, or cycle outdoors, select the appropriate Workout and bring your iPhone. For GPS accuracy, you can also calibrate your Apple Watch. Apple Watch Series 2 or later has built-in GPS that allows you to get more accurate distance and speed information during an outdoor workout without your paired iPhone.