The OnePlus 5T is sold globally but if you purchase your handset from China, chances are, it'll arrive with some unfamiliar software. Luckily, it's quite easy to convert from HydrogenOS to OxygenOS.
Hydrogen os RSS
An update to HydrogenOS 3.0 has been released for both the OnePlus 3 and 3T bringing additional improvements and optimizations, but stops short of bringing the OS up to Android 7.1.1 Nougat.
Hydrogen OS 3.0 - which is based on Android 7.0 Nougat - is now available for OnePlus 3 and 3T devices. The update contains a number of improvements and functionalities including call recording.
While many users are anxiously waiting for Android 7.0 Nougat, OnePlus is currently working on a new version of its operating system, OxygenOS 3.5, which is still based on Android 6.0.1 Marshmallow.