I've restored manufacture settings on my iphone 4, but never updated the software. How do I unlock it now?

I received my upgraded phone, so restored my manufacture settings on my old iphone 4 so that I could sell it. I never updated the software on the iphone 4. The phone is now locked and just informs me to plug into itunes or make emergency call. When I plug into itunes nothing happens. How do i unlock it??