AT&T announced Wednesday it will support calling over a Wi-Fi network from the LG G4 phone, with other Android devices to follow.
Wi-Fi calls recently became available to customers using iPhones and other iOS 9.3 devices on all four major U.S. carriers, which includes AT&T, Verizon, Sprint and T-Mobile. That iOS update first became available March 21.
Wi-Fi calling is ideal for places were there is limited or no cell coverage. Many indoor spaces don't provide good cellular connections, so Wi-Fi calling is a suitable alternative. Travelers abroad can reduce roaming costs by using Wi-Fi calling as well.
"Wi-Fi calling is a feature that customers want, so that's the most important reason for carriers to do it," said Roger Entner, an analyst at Recon Analytics.
T-Mobile advertised Wi-Fi calling as a replacement for inconsistent cellular service as early as 2007 before getting a permit from the Federal Communications Commission to do so.
AT&T explained that its Wi-Fi calling requires a compatible device and a postpaid wireless account set-up for HD Voice as well as the Wi-Fi connection.
Users on AT&T's Wi-Fi calling system can make and receive calls and texts and keep the same phone number. The bill for a call is based on the number being called. For AT&T customers, making a call on a U.S. number to another U.S. number is free, even if the customer is overseas, according to an AT&T blog and a separate online description.
After T-Mobile, Sprint began offering Wi-Fi calling services earlier than the much-larger AT&T or Verizon, although there are differences between what the carriers offer and the devices they support. Verizon now lists 13 smartphones that support Wi-Fi calling on its website, including six Android phones-- the Samsung's Galaxy S7 and S7 Edge and Note 5 and the HTC 10 and LG G5 and V10.