Sprint's iPhone customers will gain access to Apple’s enhanced Wi-Fi calling feature with the newly released iOS 9.1.
The capability, which is supported on iPhone 5c and later, enables users to make and receive calls from multiple devices with a single number.
Other countries/carriers supporting Apple's Wi-Fi calling include: Canada (Bell, Rogers), Hong Kong (EE, Vodafone), UK (EE, Vodafone), Saudi Arabia (Zain), Switzerlan (SALT, Swisscom), US (T-Mobile)
https://support.apple.com/en-us/HT203032
http://www.sprint.com
