See dear if u have 4.3.3 or later
1: download redsnow form this link:
https://sites.google.com/a/iphone-dev.com/files/home/redsn0w_win_0.9.9b9d.zip?attredirects=0& d=1
2: enter ur iphone in DFU mode by following the same steps in this program
3: check mark in install ipad baseband
4: after done, to make ur sim card work install ultrasn0w from Cydia
That set