No word on update for original Galaxy S4 on the carrier
The tri-band Galaxy S4 (that's the one with Sprint Spark capabilities) is the latest Sprint device to get the recently-introduced Wifi Calling feature. This means after the update you'll be able to make completely free calls when connected to Wifi without the potential of using up your minutes if you don't have an unlimited talk plan.
Best of all the service itself is free, with no strings attached — your phone will handle the move to Wifi calling seamlessly in the background. The update for Wifi Calling will be rolling out to all tri-band Galaxy S4s (sorry, the original Galaxy S4 isn't included in this rollout) starting today, with all updates being completed in a few weeks.
Sprint still plans to bring Wifi Calling to additional devices throughout the year, but it's good to see it at least getting to the most popular devices first.