I am trying to set up an iPhone 4s , but I can't set it up because the SIM card I'm using keeps saying that it is invalid. I think the phone is locked to a US cell carrier. I would like to be able to activate it and jailbreak it so I can unlock it. Can anyone point me to a tutorial on how to do this please.I have watched a couple of videos on doing it by using the emergency call feature , and entering a certain code. I wasn't sure if these tutorials were still valid , though.