How Do I Figure Out What My Firmware Is On My Unactivated Iphone

I have an unactivated iPhone that i need to unlock, but i can't figure out what firmware it is running. I can't get on the homescreen and go to settings, the general and find it out there cuz i don't have at&t. And when i plug it into itunes it says insert sim or activate account or something and doesnt let me do anything.