I've spent days going over forums and Apple documentation on this issue. Bottom line, if you're with Wind, you cannot activate your phone number for Message or FaceTime.
So today, I spent hours on the phone with Wind and Apple to try and get to the bottom of the issue.
I had to go through rounds of discussion to prove all remedies had been tried and failed and that this was an Apple/Wind problem that would only be solved by them working together to identify the problem and fix it.
I persisted until I finally escalated the issue to the point where Apple is "opening a ticket" to address the problem with Wind.
They said to give it a few days.
Fingers crossed....