Carrier Use ATT Unlimited SIM

[Sparticu$]

I have a Samsung Galaxy s3 on att with unlimited data when I put the sim in my ipad it says I have run out of data. I'm assuming I need to edit the apn settings of my ipad but I don't see the option under cellular settings. I have an att ipad 4

 

[Nautilus007]

I have heard if you attempt to do things like this with an iPhone unlimited sim to an iPad, they downgrade you. Not 100% but I'd be careful.