There are like three of four threads with this question so maybe you should be helpful to yourself and use search??
Originally Posted by ddarvish
Anyway I will say the same thing I did in the other thread which may help. Just because you probably wont search to find it anyway. The last time I JB my phone I took the SIM out during the process. When I connected the phone to iTunes it tried to verify and without the SIM went into the emergency call screen prompting me to insert a SIM without a lock code or enter the lock code. My phone is locked to Fido and my SIM is Fido so once I put my SIM in the phone did a verify and it was open again. So if yours is on that screen I don't know if any SIM will work or it has to be the SIM that the phone is locked to, in your case AT&T. So if your friend gave you the phone and he has AT&T borrow his SIM pop it into the phone. Once it unlocks you will have to JB and unlock the phone so it can accept any SIM if you have a SIM. If your friend is not with AT&T then look on ebay or kijiji to find an AT&T SIM, I'm not sure if the SIM has to be active or not, but it's worth a shot since all you've got is a paper weight right now.
Another option is to throw the phone up on ebay for sale and use the money to buy a touch if that's all you want, or another unlocked 2G iPhone.