Over the past year, T-Mobile has unleashed a series of bold new initiatives aimed at stealing customers away from wireless giants AT&T and Verizon. So far, fellow underdog carrier Sprint has responded with… Framily Plans. However, leaked documents obtained by AndroidCentral suggest that Sprint is planning to step up its game a little bit in the near future by offering its subscribers Wi-Fi calling, a feature that essentially lets you have unlimited calling as long as you can hook up to a Wi-Fi network. Of course, T-Mobile has had Wi-Fi calling available in some capacity for years so Sprint isn’t exactly breaking new ground here. AndroidCentral’s leaked documents suggest that the first Sprint devices to get access to Wi-Fi calling will be the Samsung Galaxy S4 mini and the Samsung Galaxy Mega.