Phone number update
I recently bought Iphone 13 and logged in with icloud id however when I was trying to add my phone number it's showing that the number is not available like this. What to do to add the phone number?
iPhone 13
Is that phone number linked to another iPhone?
You can only link a phone number to one iPhone.
Sign in to your Apple ID account page and edit / update your Apple ID details.
-> check what your trusted phone number is.