Please help unlock 3gs firmware 4.2.1

[vietkool]

finishing 4.2.1 with Redsn0w (0.9.6b5) method. then I add ultrasn0w to unlock. after install ultrasn0w then reboot device but the phone keep on searching network ( 3G off)
firmware now 4.2.1 (8C148a)
modem 05.15.04

please anyone help

[Simon]

That baseband cannot be unlocked, you would need to update to the ipad baseband to unlock.

[vietkool]

I got it unlocked now. the modem upgraded to 06.15.00. is this required to tethered everytime turn off/on the device?

[Simon]

Depends on what bootrom version you have.

[vietkool]

i disconnect the usb cable from iphone, then turn off and on again after loading the apple logo then going to phone with few second of searching network, it popup T-mobile which mean I dont need to use tetheret rite? (does is do anything with WIFI cuz i have it "on" when it reboot ?

[Simon]

If you can reboot and still get signal from tmobile then you are untethered.

[vietkool]

ok, I think i am luck out. Did reboot and get signal fine without using Redsn0w to reboot.

thanks

[Simon]

No prob