I've a used iphone 3GS. I tried to jailbreak it for firmware 4.0 yesterday following instructions here: http://www.youtube.com/watch?v=q4L0ZMP_nzo Now, the phone is jailbroken now and the sim card is in the phone, but it is not taking any cell phone or wifi signal it seems. Is it locked and do I need to activate it ? if so, how do I do it ? Both iphone and sim card (AT&T) are used. After jailbreaking, in iTunes, I chose "set it up as a new phone". How do I get the phone to work now ????