Sprint adds Wi-Fi calling to Samsung Galaxy Note 3 with update
If the update hasn't hit your Sprint branded Samsung Galaxy Note 3, there is no need to pout, kick the neighbor's cat, or even kick the neighbor. The update containing Wi-Fi calling is being sent out on a staggered basis, which means that it won't be sent to everyone at once. The carrier says it could take several days for the update to reach your phone.
Sprint has said that it will be adding the Wi-Fi calling feature to additional Android models as the year progresses.
source: Sprint via AndroidCentral