Error when I am active FaceTime on my iPad Pro

If having difficulties with FaceTime activation on your iPad, this support page should be helpful in resolving the problem:

If you get an error when trying to activate iMessage or FaceTime – Apple Support

What is the model number of your iPad? Settings>General>About>Model.

You may have to scroll to see the entry for Model.

Since iOS 12.2, the Model Name is displayed as well as a generic model code