How to upgrade modem firmware to 6.15.00

[BahamaGirl]

Hi,

I have successfully used the GreenPois0n jailbreak on me 3GS iphone with 4.2.1 and modem firmware of 05.15.04. I now need to upgrade the modem firmware so that I can unlock with ultrasn0w. Is it possible to do without using Redsn0w - I don't want to have a tethered jailbreak.

Thanks,
BG

[NBG]

You can easily update phone with redn0w, just uncheck install cydia and check install ipad modem.Phone will be untethered after this.

[BahamaGirl]

Hi,

Thanks for the info - but i have tried two versions of Redsn0w and the program keeps crashing mid way through the process. Can you tell me what I am doing wrong. I have run in XP compatibility mode and as Administrator. Anyone have any other ideas??

Thanks

[safinge]

Hi, I have an iPhone 3G, with iOS 4.2.1, and baseband 05.15.04

I've also tried the Greenpos0n, redsn0w, cydia, Ultrasn0w, etc... and I've successfully jailbroken my phone, but I haven't been able to unlock ti to use any SIM Card.

I've tried doing the redsn0w jailbreak again with the iPhone iPhone1,2_4.2.1_8C148_Restore.ipsw, but the redsn0w just keeps crashing midway when rebooting the iPhone on DFU mode.

Please, let me know if I'm doing something totally worng, or if there's some other way to unlock iPhones....