All but one major U.S. wireless carrier offers Wi-Fi calling to its customers — but that's about to change. Verizon customers will finally get this feature tomorrow (Dec. 8), starting with the Samsung Galaxy S6 and S6 Edge. The feature rolls out to other Verizon handsets early next year.
Wi-Fi calling allows you to phone your friends over your home or office's Internet connection without having to use a separate app such as Viber or WhatsApp. Calls over Wi-Fi generally do not count toward your plan's minutes, and also are handy in areas with limited cell coverage, such as in office buildings or basements. This lets carriers cover more areas, considering the number of public hotspots available today.
To enable Wi-Fi calling on your Galaxy S6 or S6 Edge, you'll have to download a software update, then turn on Advanced Calling from the Settings menu. After that, turn on Wi-Fi Calling. Once that's set up, when you travel out of your 4G LTE network the call will "seamlessly transfer to a known Wi-Fi hotspot when available," according to information from Verizon.
How Wi-Fi Calling Compares on the Big Four Carriers
Verizon is the last of the Big Four carriers to activate Wi-Fi calling on its phones. Sprint and T-Mobile have offered that feature since 2014, while AT&T added the service in October this year. While Wi-Fi calling is only available on iPhone 6, 6s, 6 Plus and 6s Plus (running iOS 9 and up) on AT&T, T-Mobile's service is available on dozens of its Android and iOS phones, as is Sprint's.
Both AT&T and Verizon make it clear that Wi-Fi calling only kicks in when the carrier's cellular network is weak or non-existent, while T-Mobile and Sprint prioritize Wi-Fi over cellular when you're within range of a hotspot.
Verizon and T-Mobile promise that calls will switch seamlessly between 4G LTE and Wi-Fi; AT&T and Sprint both don't support that switching. Calls over Wi-Fi within the United States and to any U.S. number from international locations are free across Verizon, T-Mobile and Sprint, but AT&T only allows free Wi-Fi calls between U.S. numbers. You can call an international number over Wi-Fi on AT&T, and you'll be charged for that call based on your plan, but those abroad can't call U.S. numbers, an AT&T rep told me.
In all, Verizon's Wi-Fi calling is more of a way to extend coverage in areas with spotty reception but that have Wi-Fi, as opposed to the more cost-saving implementation of T-Mobile and Sprint. The latter two carriers have more Wi-Fi Calling-compatible phones and offer a service more similar to that of low-cost carriers such as Republic Wireless, which prioritizes Wi-Fi connections over cellular for its affordable lines.