It's been a few months, but OnePlus is again updating its 2015 flagship to a new version of the OxygenOS software, v3.5.5. The OTA brings a slew of new things, the most notable being VoLTE support. This update comes with a few caveats, which we'll get into after the changelog.

  • Enabled VoLTE functionality for select carriers
  • Added App Lock
  • Added Battery Saving Mode ( Settings > Battery > More )
  • Added Gaming Mode ( Settings > Developer Options )
  • Added Additional Options for the Alert Slider.
  • Redesign of the Volume Adjustment Bar
  • Shelf Optimizations
  • Updated OxygenOS UI
  • Updated Interface and UI of the Clock app
  • Updated Android Security Patch Level to 1/12/16
  • Increased System Stability
  • General Bug Fixes

Those changes bring the OnePlus 2 more in line with this year's flagship(s), which is great to see. However, the forum post does specify a few things to keep in mind when upgrading to this new version:

  • Clock, Calculator, and Messages will be REPLACED by stock OnePlus apps if you have never updated the corresponding Google apps. But you can download these apps from Google in the Play Store even after the replacement.
  • Many of the phone settings will be restored to default after upgrading to 3.5.5, for instance device name, ringtones, accent colors, and status bar battery indication will all be reverted to default settings.
  • After updating to 3.5.5, basic functions like WiFi connectivity, Network and Fingerprint might be affected if users flash back to 3.1.0. Users will have to use a special 3.1.0 downgrading version and flashing tool that will wipe all data from the phone. You should back up if you want to revert to older versions from 3.5.5 without losing data.

It is possible to downgrade back to v3.1.0 if something goes wrong with this update. OnePlus has graciously provided instructions to do so. The company is also keen on user feedback, so be sure to provide some after you've had a chance to play around with the new version.