- Backup the iPhone using iTunes
- Try this method.
- If that didn't work, then try the following steps.
- Upgrade your iPhone 3GS to 6.1.3 using iTunes
- Download Redsn0w 0.9.15b3 from here
- Download iOS 6.0.0 IPSW from here
- Open up Redsn0w, select Extras then Select IPSW
- Select the downloaded iOS 6.0.0 IPSW
- Now, from the main screen in Redsn0w just click Jailbreak and make sure you follow the instructions that will appear on the screen. Select install Cydia.
- If Cydia is not installed then go to extras hit select IPSW again and click the same 6.0 and then click just boot
- After booting connect to the internet through WiFi
- From Cydia install p0sixspwn and ultrasn0w.
- p0sixspwn will untether the jailbreak.
- ultrasn0w will unlock the provider and allow you to use your SIM.