Apple has just released iOS 1
The good news is you do not have to worry about this mistake now. Apple says the group FaceTime is permanently disabled on iOS 12.1.3 and macOS 10.14.2 as well as older versions of the software.
The bad news was that you could not use the FaceTime group for more than a week while Apple was working on the repair. As Apple's system status page finds out, Group's FaceTime servers are back online and you can re-make FaceTime group calls-but only after the update.
To update an iPhone or iPad, go to Settings> General> Software Update on your iPhone or iPad and install the update. On a Mac, go to Apple Menu> System Preferences> Software Update.
After you install the update, you can feel safe. Enable FaceTime on your iPhone, iPad or Mac.
On an iPhone or iPad, go to Settings> FaceTime and turn FaceTime on. On a Mac, start FaceTime and choose FaceTime> Turn FaceTime On.
You must repeat this step on every iPhone, iPad, and Mac you own. The option is controlled separately for each device.
This fix was originally scheduled to arrive last week, but Apple delayed it. Now it's finally time. This delay did not put anyone at risk, as Apple had already shut down the FaceTime server group, but now iPhone, iPad, and Mac users can re-use the FaceTime group errors in FaceTime. Disable now