2.2.1

[mattpreston11]

Is it possible to carrier unlock my 3G with 2.2.1 firmware and baseband 02.30.03 or 2.9 whichever one it is..

Help appreciated

[benflick]

Nope, there are SIM unlocking tools, but most are garbage and hardly work.
Try downgrading the baseband to 2.28.00 for Yellowsn0w to work by getting 3G Fuzzyband Downgrader from Cydia.
Note: this only works on iPhones with the 5.08 bootloader, so don't be surprised if you aren't successful.