How to activate my iPhone 4S without a SIM card?

[alineunzelman]

I got this phone and I'm not sure what the carrier is...I have AT&T SIM card but get this message saying it that my server is temporally unavailable... What do I do?

 

[Alli]

When are you getting that message? Where did you get the phone (if you're in the US, there's a good chance it's an AT&T phone).