Two Step Authentication method for Apple ID no longer works.
My nonagenarian father is trying to figure out his iPhone and his computer, (it's a constant process) and has an Apple ID to connect to all his info and download apps, etc.
However, the two-step authentication number he used was for a land line to his old home.
That phone number is no longer available, and he can no longer log into to his Apple ID.
What are his options? How can he change the two-step number?
Thanks.