This phone number is already in use issue
So I recently had my phone stolen and got a new one with the same number and is says it has an account already using it what do I do?
iPhone XR, iOS 14
Are you using a different Apple ID on your on your new iPhone than what was on your old iPhone? If you are using a different / new Apple ID, then that could be the reason that Apple is telling you that your phone number is associated with another Apple iD. Try using the same Apple ID that you used with your old iPhone and see whether that helps.
Axel F.