T-Mobile has posted the changelog for an over-the-air update now rolling out to Xperia Z1s owners. The primary new feature is the inclusion of in-flight texting support. This way users can communicate with folks on the ground for free via Gogo thanks to a partnership T-Mobile debuted a couple months back.
This isn't all the OTA has to offer. The update will provide the Xperia Z1s with Wi-Fi calling enhancements, which are always a nice thing to see considering the carrier's reliance on Wi-Fi networks to complement its cellular network.