AT&T enables international Wi-Fi calling with iOS 9.3

Apple iPhone owners who updated their device to iOS 9.3 are being notified via text message of AT&T's international Wi-Fi calling feature, a service that allows users to place calls to — and receive calls from — the U.S. without incurring airtime charges.

In free texts sent out to AT&T customers on Tuesday, the U.S. wireless provider said its latest carrier software update extends months-old Wi-Fi calling capabilities beyond domestic borders. The feature is sure to be well received by jet-setters keen on avoiding high international roaming charges. AT&T notes calls to and from international numbers will be charged at rates commensurate to a customer's smartphone package or international calling plan.

Aside from the obvious cost benefits, Wi-Fi calling is useful in areas with poor cellular coverage, a common occurrence in when traveling abroad. While supported in many countries, the feature is currently restricted in China, Cuba, India, Iran, Israel, North Korea, Pakistan, Saudi Arabia, Sudan, Syria, Turkey, the United Arab Emirates and Vietnam.

To enable Wi-Fi calling on iPhone, visit Settings > Phone > Wi-Fi Calling and toggle the "Wi-Fi Calling on This iPhone" switch to the on position. Users activating the service for the first time might have to navigate through an initial setup process. Currently, the feature is limited to iPhone 6, iPhone Plus, iPhone 6s and iPhone 6s Plus models.

Once Wi-Fi calling is enabled on a user's iPhone, and when connected to a Wi-Fi network, the system automatically reroutes incoming and outgoing calls over the Internet. Subscribers can use their regular phone number with the service, so there is no need to remember a special access number or download a special app.

AT&T first introduced Wi-Fi calling on iPhone last year, first rolling out access to a select group of beta testers before opening access to all eligible customers in October.