AT&T started rolling out the Android 5.0.2 Lollipop OS update to the 2014 edition of Moto X. Following the rollout by Verizon and US Cellular, AT&T began seeding the new firmware to the handset since Motorola is one of the first Android OEMs to receive the upgrade. 

The Android 5.0.2 Lollipop OS update for AT&T Moto X (2014) has a software number 22.21.34 and the file is as big as 600 MB. 

According to AT&T's changelog, the Android 5.0.2 Lollipop OS will bring the new Material Design, New Interruption, Downtime settings, and Overview space. In addition, the smartphone will also have the new lock screen notifications that will allow users to customize their notifications for each app and Quick Settings. Other improved features of the OS are security improvements, performance boosts, dynamic status bar, Smart Lock, Screen Pinning, better battery statistics, battery saver mode, and more. 

AT&T users will receive the OS upgrade in phases, which means that some handsets will get the update earlier than others. If the smartphone is ready, the user will receive a notification that the update is now available for download and they just have to tap to install. If no notification is received, users can do a manual check in the phone's Settings > About phone > Software updates > Check now. 

It is best to download the operating system via Wi-Fi network and the battery should have at least 50 percent battery juice.

While the latest Moto X (2014) is now enjoying the latest operating system, its predecessor, the Moto X (2013), is still waiting for the update. According to @motorolasupport, the update for the handset is not ready yet, and the tech company has not announced any specific date for its rollout.