So i have an iphone 3gs that had 3.1.3 on it, jailbroken, but not sure if the shsh blobs were backed up on cydia and i updated to 4.0.1 and i dont have a sim card for it. i have a t-mobile for it, but im not sure if there is a way i can somehow restore it to 3.1.3, or even 4.0 and go into cydia and do ultrasn0w. When i restored it will now just sit at, no sim card installed or if the t-mobile one is, says it cant be used duh because its not unlocked. i just need this jailbroken and unlocked on the newest firmware. can someone help? thanks also if i cant get it unless i need a sim card, can i just use a friends from att and pop it in and it just works? not sure how the sim part works on that. caz if it works that way cant i just jailbreak it and go to cydia and be able to unlock?