If you want to check iPhone unlock possibility there are few ways to do that. There are different methods of unlocking starting from easiest software methods (ultrasn0w unlock), SIM card interposers and totally extreme ones like changing baseband physically. Peaople are ready to do everything to get their phones unlocked. If you want to unlock too but not sure what to start with, this guide will help you. Firstly you have to check your baseband firmware version you're on.

To check iPhone unlock availability you can:

• Open Settings and go to General->About and scroll down until you see the modem firmware version
• Grab f0recast from iH8sn0w.com. Just connect your phone to PC, run the tool and it will tel you what baseband you are on
• Get TinyUnbrella from official site. Run it, choose your phone and look for your baseband version under 'installed baseband' line

Second and third options are preferred when your phone cannot boot or you can't look for your bb version for some reason. When you know your bb version you have to check if it can be unlocked: iPhone 3G/3GS Baseband Firmware Unlock 4.26.08 3.0/3.0.1 Yes (Ultrasn0w) 5.11.07 3.1/3.1.2 Yes (Ultrasn0w/blacksn0w) 5.12.01 3.1.3 Yes (Ultrasn0w) 5.13.04 4.0/4.0.2/4.0.3 yes (Ultrasn0w) 5.14.02 4.1 None *See below on how to unlock if here 5.15.04 4.2.1 None *See below on how to unlock if here 5.16.01 4.3 None *See below on how to unlock if here 5.16.02 4.3.X None *See below on how to unlock if here 5.16.05 5.0/5.0.1/5.1 None *See below on how to unlock if here 6.15.00 Custom Firmware or redsnow method yes (Ultrasn0w) iPhone 4 Baseband Firmware Unlock 1.59.00 4.0/4.0.1/4.0.2 Yes (Ultrasn0w) 2.10.04 4.1 Gevey Sim 3.10.01 4.2.1 Gevey Sim 4.10.01 4.3.X Gevey Sim 4.11.08 5.0/5.0.1 None 4.12.01 5.1 None iPhone 4S 1.0.11 5.0 None 1.0.13 5.0.1 None 2.0.10 5.1 None * Bb can be downgraded ONLY if you have iPhone 3G with 5.8 bootloader. To find out run either f0recast or TinyUnbrella. If you're lucky to have that version of bootloader on your phone - use Fuzzyband from Cydia to get your bb downgraded. You can always check if the unlock available from the original sources: Dev-Team Blog MuscleNerd (MuscleNerd) on Twitter sherif hashim (sherif_hashim) on Twitter Stefan Esser @i0n1c pod2g@pod2g Or use my personal twitter list of most powerful iPhone/iPad jb and unlock hackers