AT&T on Wednesday announced it is launching Wi-Fi calling for Android.

The service – which allows users to make and receive calls and text over Wi-Fi – will initially be available on just the LG G4, but will “soon” become available on other Android devices, AT&T said.

AT&T said billing for Wi-Fi calls is based on the number you’re contacting. Calls over Wi-Fi from a U.S. number to another U.S. number will be free of charge, even if the user is overseas, AT&T said. AT&T’s Wi-Fi calling can be used across the U.S., Puerto Rico and U.S. Virgin Islands, as well as “most” international countries, the carrier said.

Text messages sent over Wi-Fi count against a customer’s rate plan the same as regular text messages, AT&T said.

Wi-Fi calling was first offered by AT&T last year, but until now was only available on compatible iPhones running iOS 9. Wi-Fi calling-enabled iPhones include the iPhone 6, 6 Plus, 6s, 6s Plus and SE. The service is available to AT&T postpaid customers only.

AT&T’s roll out of Wi-Fi calling has lagged significantly behind that of competitors like T-Mobile and Sprint, partially because the carrier delayed its roll out of the service to wait for an FCC waiver for text telephony (TTY) requirements. That approval came in October of last year.

T-Mobile and Sprint did not file for an FCC waiver before launching their Wi-Fi calling services in June 2007 and early 2014, respectively. Sprint, which initially offered Wi-Fi calling on Android devices, opened the service for iOS in April 2015.

Like AT&T, rival Verizon also waited for a TTY waiver from the FCC before rolling out Wi-Fi calling for Android devices in December 2015. Verizon expanded its Wi-Fi calling service to include the iPhone 6 and all newer models running iOS 9.3 in March of this year.