While the ZenFone 4, 5, and 6 product lines are not considered to be Asus' flagship devices, the Taiwanese company still rolled out the Android 5.0 Lollipop updates via over the air download to bring the products up to date with the current smartphones in the market today. 

Users of the ZenFone 4, ZenFone 5, and ZenFone 6 devices were actually not expecting to receive the mobile operating system upgrade this soon since early reports claimed that Asus was having a hard time fixing the issues with the Lollipop rollout. 

Just last week, Asus India issued a statement claiming that the Android Lollipop upgrade for the first-generation ZenFone devices has been delayed to further improve the system, as well as work on the issues that could affect seamless user experience. But since the upgrade became available earlier than expected, it means that the Taiwanese mobile phone maker managed to iron out the bugs that they earlier announced. 

Currently, the latest Android 5.0 Lollipop update with build number V3.23.40.52_20150522 was sent out to two ZenFone 5 variants, the A500CG and the A501CG. Then the firmware that comes with the build version V7.3.3 and V3.23.40.52_20150522 also arrived to upgrade the mobile operating system of ZenFone 4's A400CG/CXG model as well as ZenFone 6's A600CG and A601CG variants. 

To download the new update, ZenFone users should respond to the update notifications with a "Yes, Download" option to initiate downloading. After that, they should select the "Install now" option. Once finished, the device will automatically restart and the new operating system will be up and running for the device after that. 

On the other hand, the manual OTA update can be achieved by following these instructions: Go to "Settings," then choose "About phone," and select "System update," and click on "Check now." 

Aside from OTA downloads, users can also opt to link their ZenFone devices to their PCs to upgrade to Android 5.0 Lollipop.