whats ya baseband mate ? im my daughters ive just downgraded is 5.12.02 ive just tried fuzzyband and ultasn0w and no look but i did find this
100% working 4.1 3G bootloader 5.08 modem 5.14.02 downgrade and unlock !
solution. just download this
Ice - 5.12.02 extract the ice2-05.14.02.cert
copy it to your fuzzyband folder in iphone using ifunbox or winscp or diskaid. then run again fuzzy.
besure you have mobilesubstrate and ultrasnow already installed (cydia)
for BL 5.08 3g only.
fuzzyband folder is loacated in private/var/stash/applications