what do i do?

[Benz63amg]

so i bought me an iphone 4s with my friend's upgrade, i turn the iphone 4s and in the activation screen it says his phone number, i called at & t and im on the phone with them right now, they transfered me to apple, is there nothing that can be done or do i have to go into an apple store?

 

[r.j.s]

Put your SIM in it and give your friend the SIM currently in the phone.