My iPhone says device blocked from network service how do i fix it?

I took my AT&T simcard out of my white iphone4 and put it into a newly restored, black iphone4, started it up, and then put the simcard back in my white iphone4. Now when i try to text, it fails, and the calls just say: device blocked from network service: how do i fix this?

You should probably turn it all the way off your restart it. If that doesn't work than contact your go over to AT&T and ask them about it!