Unable to activate Messages and FaceTime with my phone number on iPhone 16 Pro Max

I have been trying to activate my iMessage and FaceTime on my phone number but it only waits for activation and shows error that says ‘An error occurred during activation. Try again.’ and it’s been 2-3 days of constant trying. I watched multiple YouTube videos and comments and tried every possible method and yet it doesn’t work, can some help?

[Re-Titled by Moderator]