Wi-Fi calling lets your iPhone to place and receive phone calls and text messages with your Wi-Fi network. If you have a weak cellular signal but a solid Wi-Fi signal, your iPhone will automatically switch over and route calls and texts via Wi-Fi.
Apple added support for Wi-Fi calling to the iPhone with iOS 8, and it’s gradually becoming supported by more carriers. You can only use this if your cellular carrier supports it.
Things You Need to Know
You’ll have to enable it before it will do anything because it is disabled by default. Once you’ve enabled it, it will “just work” and your phone will automatically switch to Wi-Fi when necessary. You’ll see this indicated in the status bar. For example, it will say “T-Mobile Wi-Fi” rather than “T-Mobile LTE” if you’re using T-Mobile and your phone is currently connected to Wi-Fi rather than the LTE cellular network. Dial a number or send a text message in the normal way while “Wi-Fi” appears in your status bar and it will connect over the Wi-Fi connection instead of the cellular one.
It’ll automatically switch between cellular and Wi-Fi networks as you move out of an area covered by Wi-Fi, so you don’t have to do anything different or even think about it.
This only works if your carrier supports it. The carrier has to be able to automatically route calls and texts to you over the Internet.
Two Things You Need
There are just two things you need, a carrier that supports Wi-Fi calling: In the US, T-Mobile, Sprint, and AT&T support this. Bell and Rogers support it in Canada, EE and Vodaphone support it in the UK, and 3 and SmarTone support it on Hong Kong. More carriers should support it in the future.
An iPhone 5c or newer: Older iPhones like the iPhone 4s don’t support this. You’ll need an iPhone 5c, 5s, 6, 6s, or a newer model to use this feature.
How to Enable Wi-Fi Calling
To enable Wi-Fi calling, open the Settings app on your iPhone, scroll down, and tap Phone. Tap “Wi-Fi Calling” under Calls and activate the “Wi-Fi Calling on This iPhone” slider.
You should also tap “Update Emergency Address” and make sure your carrier has a correct address. If you ever dial 911 over a Wi-Fi network, the emergency responders will see your call associated with the emergency address you enter here.
If you ever encounter a problem with Wi-Fi calling, you can visit this screen again and disable it with a quick tap.
Using Wi-Fi Calling Along With Continuity
Wi-Fi calling doesn’t usually work with the Continuity feature. You won’t be able to receive calls on your Mac or another iOS device like an iPad if you enable Wi-Fi calling.
Apple is slowly work on this. If you have iOS 9 and OS X El Capitan, you can now use the standard Continuity features along with Wi-Fi Calling. If you’re with T-Mobile in the US. No other carriers yet support this.
You can enable this feature from the Phone screen in the Settings app. Go to the Wi-Fi calling option on the Phone screen, tap “Calls on Other Devices.” Tap “Add Wi-Fi Calling For Other Devices” and other devices signed in with your iCloud account will be able to place and receive calls normally even with Wi-Fi calling enabled. Again, carriers will have to go out of their way to support this currently, only T-Mobile in the US allows this.