Hi, I bought an iPhone 5 from Apple on an AT&T contract and then sold it for a profit on eBay to somebody also on AT&T. They are having a hard time with activating the device as it apparently requires my billing zip and last 4 digits of my SSN to activate. I removed the SIM card before shipping the phone. An AT&T rep told me I have to activate with my info, which will deactivate my own phone line until I go to the AT&T store and ask for a new SIM card. Is this accurate? How can I help my ebay buyer activate his new phone? Thank you!