No Service fix for iOs 6.0.1
Have you updated your iPhone 3GS or iPhone 4 to iOS 6.0 or 6.0.1 and are trying to unlock it? We all know that after jailbreaking an iPhone, we can unlock it (If it is on unlock-compatible baseband. See list below) by installing ultrasn0w from Cydia.
You can check your iPhones baseband by going to Settings > General > About > Modem Firmware. Ultrasn0w can unlock following iPhone 3GS and iPhone 4′ basebands:
01.59.00 Ė Only iPhone 4 baseband that ultrasn0w can unlock
If you have updated your iPhone 3GS or iPhone 4 to iSO 6.0 or iOs 6.0.1 and are on one of those unlock compatible basebands, you will be getting no service even if you install ultrasn0w from Cydia. Why is it so? Because the dev team hasnít updated ultrasn0w to be compatible with iOS 6. So is there any solution? Yes, there is a temporary solution to this problem until dev teams updates ultrasn0w. Read on.
Before your proceed, uninstall ultrasn0w and eject your sim card. Open Cydia and go Manage > Sources. Tap Edit and then Add and write down the following.
Hit Add source. Once the source has been added, search cydia for Ultrasn0w Fixer for 6.0 and install it.
Now reboot your device. (Remember: Your device is tethered jailbroken. You will have to boot it using Redsn0w otherwishe it will keep stuck on apple logo) After booting up, again go to Cydia and install ultrasn0w. After ultrasn0w has been installed, insert your Sim card and you should see service from your carrier now.
Fix no service iOs 6.0/6.0.1 iPhone 3GS, iPhone 4