A common problem that many people run into is the iMessage / FaceTime activation errors. This error can happen due to many different reasons, but there are a few commons ways you can fix this. The very first way to fix this is to make sure you are connected to a reliable network. If you are connected to a super slow network, or a network that is spotty, you may not be able to activate iMessage or FaceTime. A quick way you can see if your network is reliable is to open up your web browser and load a website, if it takes a long time then chances are the network isn’t reliable and you should connect to a better network.
Another option you can do is to reconfigure your timezone in settings. Go To Settings > General > Data & Time and make sure that the timezone you’re in matches the specific timezone chosen in your settings app.
Another option you have is turning on and off iMessage. Go Into Settings > iMessage, at this point toggle on and off the iMessage, this will restart your iMessage and might fix the issue.
The same thing can be done for FaceTime issues as well, go into Settings > FaceTime, and toggle on and off the FaceTime toggle. This will restart your FaceTime and might fix your iMessage / FaceTime activation errors.