How to Unlock a G600
- 1). Replace the existing SIM card of the phone with one from another wireless network provider. For instance, if the Samsung G600 is locked to AT&T, insert a SIM card from T-Mobile or another network provider.
- 2). Power on the phone.
- 3). Type "*2767*3855#."
- 4). Wait for the phone to restart, after which you will see a menu on the screen.
- 5). Enter "*7465625*638*00000000*00000000#."
- 6). Type in the new code "#7465625*638*00000000#." Your Samsung G600 will now be unlocked.
Source...