How to Jailbreak, Activate Officially, and Unlock your iPhone 3G in IOS 4.2.1

Ok this is how you do it:

Read step 11 first!!!

1. Download IOS 4.2.1 firmware for your iPhone 3G here
2. Download redsnow 0.9.6b6 here: windows mac
3. Open your iTunes and connect your iPhone via USB to your PC
4. Restore your iPhone 3G by clicking the shift button (windows) and click restore.
5. Select the file that you have download in the step 1
6. Wait for restoring process until finished
7. After it finished, close your iTunes
8. Open redsnow.exe from the file that you have download in step 2.
9. Step 1 in Redsnow: browse the IPSW file that same as in step 1 or 5. Hit Next
10. Select Install Cydia, and install iPad BaseBand (this two option is a "must" checked option) for the rest is an optional if you don't know what those option are, just leave it unchecked.
11. If the warning window emerged when you checked the install iPad Baseband then read it carefully. If you agree and aware of the consequences press Yes, and if you don't agree and don't want to continue, click NO and close the redsnow hence you can not JB, Unlock and activate officially your iPhone.
12. If you want to continue after hit Yes, then hit Next.
13. Follow the instructions from redsnow, and wait until Jailbreak process finished.
14. After it finished, unplug your iPhone from your PC and tap cydia to open.
15. Open Cydia - select user - upgrade essential.
16. Open Cydia again - manage - source - edit - add - http://repo.bingner.com  
17. Wait until finished, after it finished adding bingner's repo, tap manage-source-tap bingner's repo and install both SAM and SAM Prefs.
18. After it finished, restart your iPhone and connect again to your PC via USB cable.
19. If the iTunes automatically open, closed it.
20. Open Redsnow 0.9.6b6 again follow the instruction as in step 8&9.
21. Then now select only "Deactivate" and hit next.
22. follow the instructions from Redsnow (DFU mode: as usual)
23. Wait until finished
24. After it finished unplug your iPhone from your PC
25. from your iPhone Go to Setting - SAM - and tap: de-activate iphone
26. after that restart your iPhone
27. Open your iTunes and plugged your iPhone to your PC.
28. Wait until iTunes officially acitvate your iPhone
29. After it activated, go to cydia and tap manage - sources- and tap ultran0w repo and install ultrasn0w 1.2
30. After it finished, restart your iPhone.
31. Done! now your iPhone is Jailbroken, officially activated, and unlock :-)

G'lak!! have a try!!