I can't verify Apple ID with the cellphone number
My son has a new phone after destroying his old one, and he had a different phone number to the one that was used previously for his Apple ID. When we went to set up his Apple ID on his new iphone, it asked for verification through the old phone number, which he can't use. How can we get around this? He doesn't have any other trusted device signed in to his Apple ID.
iPhone XS