Some carriers support Wi-Fi calling to make and receive calls and text messages from locations where your cellular signal is poor or not available. Contact your carrier to confirm that they support Wi-Fi calling for your phone.
Calls and texts that are made over a Wi-Fi network use your existing cellular rate plan, even when roaming:
When connected to a Wi-Fi network, your phone automatically switches between cellular and Wi-Fi networks for calls and texts based on the signal strengths.
If your carrier supports Wi-Fi calling, you need to turn it on.
Tap Wi-Fi calling.
Depending on your carrier, the Wi-Fi calling setting may be in your Phone app 

If you don’t see this option, your carrier doesn’t support this feature.


Make sure that:
Depending on your carrier, you’ll see a Wi-Fi calling icon in the status bar, start and end call buttons, or the active call status indicator when your call is over a Wi-Fi network.
If you're not connected to Wi-Fi, calls use your carrier’s mobile network.
If you're outside your carrier's network and want to use Wi-Fi calling instead of roaming on another carrier’s network:
Other reasons why Wi-Fi calling may not work:
Calls to 911 are made over Wi-Fi only if the cellular network is unavailable.
Your phone is associated with an emergency address used by emergency responders when you make a call to 911 over Wi-Fi in the US. It's important to change this address when you change locations.
911 calls made over Wi-Fi may be delayed or unsuccessful if:
Learn how to update your emergency address.