Facebook has launched its new Home app to turn Android devices into dedicated 'Facebook phones' in the UK.
Once installed, the app takes over the Android home screen of various phones including the Samsung Galaxy S3, the upcoming S4 and the HTC One.
Home is designed to replace a user's home screen, integrated text messages into Facebook chats and making social updates the focus of the device.
With Home installed, users will see their Facebook news feed as soon as they wake up their phone, and use the new 'Chat Heads' concept to talk to friends even when using other apps.
The app is now available for supported phones - and others with a bit of unofficial tinkering - from the Google Play store in the UK.
Facebook says:
"Home isn't a phone or operating system, and it's also more than just an app. Home is a completely new experience that lets you see the world through people, not apps."
Meanwhile Facebook has not yet confirmed a UK release date for the HTC First, a phone with the software pre-installed.
But it has updated its iOS app for iPhone and iPad, bringing 'Chat Heads' and other new features to Apple devices.
The update also includes "Stickers", an enhanced version of emoticons which are available to purchase from a dedicated 'Sticker Store'.