So here is the scenario - I bought an iPhone 3gs in 2010 in US with AT&T connection and used it till 2012. After completing 2 years I asked AT&T to unlock it, they accepted my request and provided following instruction to unlock it. 1.[SIZE=+0] [/SIZE]Take a backup using iTunes 2.[SIZE=+0] [/SIZE]Erase everything 3.[SIZE=+0] [/SIZE]Restore from back up However I never did that while in USA. Now I am back in India and want to unlock my iPhone so that I can use it with other SIM cards. What I have with me now are 1.[SIZE=+0] [/SIZE]iPhone 3gs with OS 3.1, 2.[SIZE=+0] [/SIZE]An AT&T SIM that has been cancelled(I terminated the service when I left USA) 3.[SIZE=+0] [/SIZE]An AirTel 3g SIM (Airtel is the official iPhone service provider in India) With the above information, can someone please guide me through the steps to unlock the 3gs model ? P.S I am not sure if AT&T unlocked it but I confirmed with Apple that they have unlocked it.