Help....4s activate problems

Hello

Just got an iPhone 5. I want to give my old 4s to my son. I've reset the 4s but when we now try to activate it it wants me sign in with the id used to set the pone up. Its gives me an old email address which i have no access to and i suspect it was another account i set up before i realized the importance of these things.

Problem is i cant re set the password as i cant get to the email account and when i go through the security it wont accept my date of birth....Help

Thanks