T-Mobile's update for the Samsung Galaxy S5 will turn on the VoLTE feature on the handset. The feature allows T-Mobile users to make/take calls over the carrier's LTE pipeline, leading to clearer calls for customers. Of course, if your area or phone doesn't support the service, you won't notice a difference despite the update. Note that T-Mobile's support page, which you can see in the slideshow, incorrectly lists the OS build number on the Galaxy S5 as being Android 4.2.2 instead of the correct Android 4.4.2. The size of the update is 30.60MB.
Two versions of the Samsung Galaxy S5, and two different updates. We do suggest using a Wi-Fi network for either update, and you should have your battery charged over 50%. You can let us know your feelings about the changes to either version of the phone, by dropping us a line in the box below.
oth the Verizon and T-Mobile version of the Samsung Galaxy S5 receive maintenance updates
source: Verizon, T-Mobile via AndroidCentral (1), (2)