Here's what to do. To confirm enter the account information that you used when you purchased the iPhone. Follow these steps: 1  Make sure that the phone number is the one that you used when you purchased the iPhone. 2  Then tap next. 3  Enter your billing zip code and the last four digits of your Social Security number.4  Then tap Next. Make sure that the phone number is the one that you used when you purchased the iPhone. 2  Then tap next. 3  Enter your billing zip code and the last four digits of your Social Security number. 4  Then tap Next.