Looks like Android Lollipop will be heading to T-Mobile Xperia Z1s (C6916) owners soon as a new build number 14.5.B.0.220 has just been certified by the PTCRB. This moves the firmware number from ‘14.4’ Android 4.4.4 KitKat to ‘14.5’ which we’d expect to be Android 5.0.2 Lollipop. We’ll keep you posted once it starts to roll.
Thanks Matthew, Tony and YassineT!