how to upgrade 3gs 4.2.1 to ios5 06.15.00 basebamd

[perezmarco]

hello. I want to update my iPhone 3GS to iOS 5 and maintain the unlock. It currently has the 06.15.00 baseband and is unlocked and jailbroken on 4.2.1. How would I go about this? How would I do it to keep the unlock but still update?

 

[nawras94]

if you have ipad baseband always use snowbreeze to build a ipsw
then go to cydia install ultrasnow
and put your sim card