The change log for the over-the-air update is as follows:
- Android 4.4.4
- HD Voice Icon
- International Wi-Fi Calling Support
- Google Security Patches
The version number for this update is G900PVPU1ANK4. As usual with these OTA firmware releases, it may take a few weeks for every Galaxy S5 device on Sprint's network to receive this update.
Source: Sprint Thanks to Reynaldo for the tip!