What’s required before you start:
Ultrasn0w 1.2.8 (only for compatible basebands).
LINKE ultrasnow 1.2.8 - Download - 4shared - asif tcn
iPhone 4 baseband 01.59.00 (that ultrasn0w supports), or 03.10.01, 02.10.4, 04.10.01 (Gevey SIM unlock method). iPhone 3GS is also for the solution on basebands 05.12.01, 05.13.04, 05.11.07 and also the famous iPad baseband 06.15.00.
Important note: Remember to back up your files before you start with any such guide.
First Part: Custom IOS 6.1.3 firmware for Baseband preservation
Step 1: Download IPSW for iOS 6.1.3 for iPhone 3GS or iPhone 4. It’s recommended that you take the official download route and save it for later use.
Step 2: Download Sn0wbreeze 2.9.14 and launch it.
Step 3: Select browse and search for the IPSW iOS 6.1.3 file downloaded in step 1.
Step 4: Select next after sn0wbreeze identifies the file.
Step 5: Select one of the follow modes:
Expert mode: baseband preservation, activates and jailbreaks.
iFaith Mode: iOS custom firmware built and attaches it to the saved SHSH blobs.
Simple Mode (mostly recommended): jailbreaks, hacktivates and preserves the baseband.
Step 6: Select Yes when you’re asked that you want to hacktivate or otherwise and wait for the process to complete.
ur desktop is going to display the custom firmware once the process ends. Before you go ahead and restore your device, the iPhone SHOULD BE PLACED into DFU mode through iREB. This makes it easy for the phone to accept custom firmware and bypass the error message displayed during restoration. iREB is located on sn0wbreeze’s menu bar and is available after the custom firmware is built.
First of all, make sure you’re in DFU mode before restoring. The black screen stands for DFU mode. Next, open iTunes, tap shift on the computer keyboard and select restore. Choose the custom firmware that was made. The file name is going to be like sn0wbreeze_iPhone+xxxxx.
Second part: Ultrasn0w 1.2.8 iOS 6.1.3 unlock via Cydia
Open Cydia and head over to Manage > Sources > Edit > Add: ultrasn0w.com.
Locate ultrasn0w 1.2.8 and install it.
Restart the phone but use iBooty to start iPhone as A4 and new 3GS phones have tethered.