The Android 4.3 OTA update for Sony Xperia Z is being pushed to the T-Mobile users as we speak. The roll out of the new firmware version has been officially confirmed by the US carrier on their support page.
The T-Mobile Sony Xperia Z Android 4.3 OTA update is labeled 10.4.C.0.797 and, as usual, is being rolled out in stages, meaning that only some of the T-Mobile customers will be able to download and install it right away. If you didn’t receive the system update notification, you might as well want to check for it manually under Settings > About Phone > Software Update > Check for updates. Alternatively you can grab the USB cable, connect your Xperia Z to the PC, then check for the new software update via Sony’s PC Companion app.
The T-Mobile Sony Xperia Z received the Android 4.2 update back in November, but in the meantime, the Android 4.3 update has been rolled for the international variant in December. Seeing T-Mobile rolling the same firmware update about two months later, is pretty typical for a US carrier.
According to T-Mobile’s support page, the Android 4.3 update for Xperia Z will bring software stability improvements, tweaks for the UXP Air interface, a redesigned WiFi Calling UI, 5 bars instead of 4 in the signal bar, and Nuance XT9 will be replaced by Swiftkey.
You should also know that the new firmware has a size of 308 MB, so we are advising you to download it using a stable WiFi network. T-Mobile also advises its users to have their battery charged to at least 50%.
For what it’s worth, Sony promised that they will bring the Android 4.4 KitKat update to the Xperia Z, but they failed to reveal when the update will be actually rolled out. Probably, the folks at T-Mobile will roll it out about a month or two after the new software hits the international variant of the phone.