On Monday I have bought the iPhone 3GS. According to the offer it should be unlocked. According to the pretty girl, that was selling me the phone, too. Well accoding to the iPhone itself - not that quite.
I tried two SIM cards before buying it but the activation failed and even not-inserted SIM card was not recognized. Because I had no experience I thought it needs to be connected to the iTunes and some updates or restore should be performed prior to activation. So I have bought it and took home.
I did the update in the evening and still the same. My SIM card was not active. I got No service all the time. The girls had perhaps jailbreak on her phone even without knowing it. She just didn't know anything. And that was the problem.
So next whole day - literally whole day - I was trying to jailbreak and unlock the iPhone 3GS. In order to see if other iOS can be installed and find out what actually the problem is. The motivation was to activate the iPhone without the SIM card.
After several hours of googling and trying some IPSW with redsn0w, I found a way how to get running iOS 4.3.3 and unlock the iPhone for any carrier.
According to software Tiny Umbrella I could install only several versions of iOS 4 and iOS 5.0.1. Apparently there were some SHSH blobs for those systems in the phone or the software found some matches online. I am not quite sure how does this all work. You should check this before doing some downgrades definitely.
This forum discussion helped me the most, mainly this entry by dbleug22990:
1.Use redsn0w to restore the iPhone to ios 4.1(ios 4.1 doesn't require backed up shsh blobs)
2.Use redsn0w to jailbreak the iphone, check the box to downgrade ipad baseband.
3.Use redsn0w to upgrade to most current firmware( this will install a new baseband and alow your phone to activate with supported sim)
So here are the most important steps I did:
I have downloaded redsn0w 0.9.15 beta 3 for Windows. You can download iOS IPSW for example here: http://ipswdownloader.com .
I. So the next step was to restore iOS 4.1 using redsn0w. You have to navigate in Extras -> Even more -> Restore.
II. Then perform jailbreak with Cydia and downgrade iPad baseband. The modem firmware version I had was 06.15.00. You can find the version in Settings -> General -> About in the iOS.
III. The modem firmware was 05.13.04 if I am right. I did a "mistake" and made the update to iOS 6.1.6 using iTunes. Then I realized for sure that this iPhone is locked because it could not be activated with my SIM. So I restored the iPhone again to iOS 4.1. At that point the modem firmware was altered.
IV. I installed ultrasn0w 1.2.8 and voilà - the SIM card was recognized and I had the GSM signal!
V. Then I wanted to upgrade the iOS to version 5. iOS 5.0.1 worked but there was some problems with turning my network on and off every minute. So finally I made restore to iOS 4.3.3 which is quite stable now. Of course after every jailbreak I had to install ultrasn0w.
A - There is some problem with the modem firmware 06.15.00 and GPS module. I realized today that it is not working properly or at all. Probably you need to downgrade the firmware again.
B - I did not want to upgrade to iOS 6 because of personal reasons
C - Be carefull and buy only unlocked iPhone!
Some perhaps useful links:
How to Downgrade iPhone 3GS iOS 6.1 Baseband 5.16.08 to 5.13.04 for Unlocking
Read more: http://www.beijingiphonerepair.com/hack/how-to-downgrade-iphone-3gs-ios-6-1-baseband-5-16-08-to-5-13-04-for-unlocking/#ixzz2w2IE8yX0
How to Jailbreak Your iPhone 3GS Using RedSn0w (Windows) [5.1.1]