One of the neat features of iOS 9 is the ability to make and receive calls via Wi-Fi. AT&T, T-Mobile, and Sprint now support this feature, with Verizon saying that it's coming soon. The advantage of this feature is that you can make and receive calls in situations where you have a good Wi-Fi connection but a weak or nonexistent connection to your cell phone service. Also, when you make a Wi-Fi call with T-Mobile's service, it doesn't count against your minutes. This feature is available on the iPhone 5s and later.
To enable Wi-Fi calling, go to Settings > Phone > Wi-Fi Calling and switch it to the On position.
You'll then see several screens that ask you to confirm that you want to enable this feature, including one that alerts you to issues regarding emergency services. (For example, if you have Airplane Mode on and Wi-Fi enabled, or if you have no cellular data access, emergency services won't be able to locate you as easily. You may be asked to provide an address where you'll likely be making Wi-Fi calls.)
Once you've enabled this feature, you can also then use your iPad, iPod touch, Apple Watch, or Mac (running El Capitan) to make Wi-Fi calls. We'll show you how to do this in a future tip.
