You can now use AT&T’s Wi-Fi calling anywhere in the world, but only with the iPhone 6

Skype and Viber are great for staying in touch when you’re traveling, but it’s not the same as having international service from your carrier. Now, AT&T customers have another option with the new International Wi-Fi Calling feature. It’s only available to customers who have an iPhone 6 or newer with iOS 9.3, and you have to have Wi-Fi for it to work, though.

Once the feature has been activated in Settings, users will be able to use Wi-Fi calling from anywhere in the world. Wi-Fi calling will be used automatically, even if you’re connected to another mobile network. That ensures that you won’t have to pay high roaming fees. The feature can be handy within the U.S. too, in places where the cellular signal isn’t very strong, like when you’re in a basement or an elevator.

One of the great things about Wi-Fi calling from mobile carriers is the fact that it’s built in — you won’t need to download, install, and sign up to a new app or service.

It’s important to note that the feature really only works if you’re calling a U.S. number. If you make a new friend while traveling abroad and call them, you’ll still be charged international calling fees. The service also has restrictions in a few countries, like China, India, Turkey, and Israel. Thankfully, the person that you’re calling does not need to have Wi-Fi calling, too for the feature to work.

“You can make calls to domestic numbers and receive calls with no additional charge and no impact on voice call airtime usage,” says AT&T on its website. “For international calls, the rates from your calling plan or international long distance package apply.”

While the feature is only limited to a select few iPhones, it’s certainly a nice addition to see, and it’s likely that AT&T will expand it to other phones as time goes on.