OnePlus is cooking a new Oxygen OS build from scratch since past couple of months. They have already provided few updates to the new build. OnePlus 3/3T has received a new Open Beta update with some changes.
The main and most important feature that have embedded in the new update is the intro of new Dialer App. Both the devices, OnePlus 3 and 3T has received new build version 15 and 6 with many changes.
There are some other changes like new action bar for Messages and Settings. Thre qare some optimizations, related to Bluetooth, night mode, and high power usage notifications. The User Interface for Messages, Settings, and Contacts has also been optimized.
The builds are available for download and you can hit the source links below in order to download them.