Please kindly help! cannot activate iPhone 4

[iNok]

I recently bought an unopened box of iPhone 4 from someone on eBay and I tried to activate it, but it requires billing zip code and last 4 digit of social security number of the owner. I then tried to call the seller. He told me that he also bought the phone from someone else and I also tried to call telephone number shown on activating screen. He refused to give me that information, so are there any way to activate and jailbreak the phone without that information? Please advise. Thank you in advance.