A new update has started hitting the Asus Zenfone 2 Laser (ZE601KL) smartphone. It arrives as version V21.40.1220.2153, and brings along a couple of bug fixes and a new security patch. Specifically, the issue where-in the LINE app volume could not be changed in handsfree mode has been fixed. The other volume-related fix has been described as "fix when playing music volume burst issue." In addition, the update also improves Bluetooth performance and updates the GMS apk. Details related to security patch aren't available. Source | Via
Source: http://www.gsmarena.com/new_zenfone_2_laser_update_fixes_volumerelated_issues-news-25991.php