Sprint said Apple’s iOS 9.1 system update enables single-number calling across Apple devices when connected to WiFi. With iOS 9.1 installed, Sprint’s iPhone customers will be able to make/receive calls from their primary number on the iPhone, iPad, iPod Touch, Apple Watch, or Mac computer.
Sprint says the feature requires several steps to enable. Customers must install the latest OS on each device; sign in with the same Apple ID across devices; initiate WiFi calling on the primary device; and assign secondary devices to the account. Calls made over WiFi don’t count against plan minutes or mobile data allotments.
The feature is free to use. Apple distributed iOS 9.1, watchOS 2.0.1, and Mac OS 10.11.1 earlier.