3G 4.2.1 Unlocking headache :(

[vestax]

Ok before i start yes i have searched for an answer but all the solutions have not worked....
Basically i have an iphone 3g 4.2.1fw and 06.15.0 basband.
jailbroken using redsnow
ultrasn0w installed via cydia
cannot get a signal with any sim? o2,vodafone,t-mobile.
ive installed,un-installed,re-installed ultrasn0w. with sim, with-out sim.

i honestly dont know what to try now as all the replys ive read on other posts say the same thing. the baseband is 06.15.00 and bootloader is 5.9 so theres no going back either
any help would be much appreciated.

[i.Annie]

Do a restore to custom 4.2.1 and then unlock with ultrasn0w again.

Or try going to 3.1.3 stock (not custom) and jb with redsn0w 0.9.4 (and a 3.1.2 ipsw) then unlock with ultrasn0w again.

You might just need a restore as sometimes things just resolve itself that way.