Even though Samsung has been pretty quick in rolling out the latest version of KitKat, Android 4.4.4, to its major devices yet Sprint subscribers are still waiting for the update on their Galaxy S5 units. The carrier itself has not revealed when it would be rolling out this update so there’s a bit of confusion at this point regarding the release timeframe.
If you absolutely must have Android 4.4.4 on your Sprint Galaxy S5 SM-G900P then there’s an unofficial solution. A pre-release build of this update has been leaked online by an “anonymous donor,” and while its not an official release it is said to be stable enough to use as a daily driver.
Link to the download file and install instructions are available at XDA forums. Since its going to be a full store which deletes data stored on the device it would be best to backup any and all data before proceeding with the update.