AT&T (NYSE: T) and Verizon (NYSE: VZ) are now offering their iPhone customers international calling services through Wi-Fi connections for no extra change. The service is available to the carriers' iPhone users who upgrade to Apple's (NASDAQ: AAPL) new iOS 9.3 operating system.

"With the latest software update for your phone you can use Wi-Fi Calling when traveling outside the U.S. This means you can call back to the U.S. or receive incoming calls, with no airtime charges," AT&T said in a text message to some customers. "When you call international numbers, your rates will be the same as those in your smartphone plan or your international package."

AT&T first began offering Apple's iOS-based Wi-Fi calling service in the United States, Puerto Rico and the U.S. Virgin Islands late last year. With iOS 9.3, AT&T is expanding the service for international calling.

As for Verizon, iOS 9.3 represents the official start of the carrier's support for Apple's Wi-Fi calling service. Verizon in December started offering Wi-Fi calling on some Android devices, starting with the Samsung Galaxy S 6 and Samsung Galaxy S 6 Edge, rolling it out as a software update in phases. In February, the carrier confirmed it would also support Apple's iOS Wi-Fi calling service in the future.

Wi-Fi calling allows customers to use Wi-Fi hotspots to make voice calls in areas where a cellular signal is tough to get, such as deep inside a building. Once the iOS service is set up, which customers can do via their settings on their iPhones under phone settings and Wi-Fi calling options, customers' phones will use Wi-Fi calling automatically in places where they have limited or no cell signal alongside a Wi-Fi connection. Wi-Fi calling works in the background, allowing users to make and receive calls like they would on the carrier's cellular network.

AT&T launched the service last year after receiving a limited waiver from the FCC for the agency's requirements to support text telephony (TTY) technology on wireless networks "to the extent that they use Internet Protocol (IP) technologies." Verizon too has received the FCC's waiver.

Both Sprint (NYSE: S) and T-Mobile US NYSE:TMUS) have offered international Wi-Fi calling on Apple's iOS platform for more than a year.

Apple released its new iOS 9.3 operating system this week in conjunction with the announcement of its new iPhone SE and its new iPad Pro. The new iOS operating system offers "Night Shift," which promises to auto-adjust users' screen color temperature at night, as well as improvements to Apple's Touch ID, News, Notes and CarPlay offerings.

For more:

- see this Engadget article

- see this RCR article

Related articles:

Confirmed: Apple's iOS 9.3 beta includes Wi-Fi calling on Verizon

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