Hi, chat isn't down. If you can't access chat you need to wait for 8 days so you get deregister from the server, then you can get chat working again. If you try before 8 days is up the 8 day clock starts again.
@smithyco@tp84: Please can you try heading to Settings > Connections > More Connection Settings > Rich Communications, and make sure that this is toggled on. Similarly, open the Messages app > Tap the 3 dots in the top right > Settings > Chat Features > On > Default Message Type > Automatic.