Jailbreak iphone 3GS 4.2.1 without changing BaseBand 05.15.04

[Sethide]

2. greenpois0n does NOT support anything after 4.2.1 and 4.3.x support is not as high a priority as iPad 2 work.

By gpadmin on April 10, 2011
Source:
http://greenpois0n.com/2011/04/10/welcome/

So here is some possibilities:
1) Do NOT update your FW and JB it with greenpois0n.
OR
2) Update your FW to 4.3.2 and Wait for the new greenpois0n to JB

 

[cobaltrich27]

iPhone Dev-Team Updates RedSn0w to Perform Untethered Jailbreak of iOS 4.3.2

Good point! I just check mine, it is indeed factory unlock
Thanks for the tips.

Just go here and follow the guide:

http://www.iclarified.com/entries/index.php