It appears that older devices are also getting a flavor of Lollipop today as Sony Xperia Z1s is receiving its OTA. Even if Sony usually releases a phone every 6 months, few make it to the US market; Z1 is one of those phones rebranded as Z1s by T Mobile. The device is now finally getting Lollipop after all that time of KitKat-ing.
The OTA is available for the T-Mobile Xperia Z1s C6916 and it brings it to version number 14.5.B.0.236. It is based on Android 5.0.2. The update is available via the system menu and you can also find a mirror on the Xperia Blog just in case you want to update manually.
Source: Xperia Blog