This is normal as Apple make the sense of ios to upgrade the baseband too, but this is not the time to wait for the unlock or downgrade the baseband, because its already out and at your hand.
jailbreak Process 
IMPORTANT FOR UNLOCKERS
During this process you can update your baseband to the 06.15 version. If you are on 05.14 or 05.15 or higher you will need to do this to unlock. You do not need to do this for jailbreak only. Please read the following very carefully before deciding whether to do this.
1. There is no way to come back down from 06.15, and there’s no hiding the baseband version from Apple. You’ll be voiding your warranty in a very obvious way.
2. If some future baseband comes out with a critical fix, you won’t be able to update to it if it remains down in the 05.xx sequence (then again, you wouldn’t update to it if you wanted to keep your unlock anyway).
3. Starting with FW 4.2.1 if you have 06.15 on your iPhone you won’t ever be able to restore to stock firmware (it will fail). You’ll need to only restore to custom IPSWs (then again, if you’re unlocker you should already be doing that).
4. There are reports that 06.15 may disable your GPS. The iPhone Dev-Team is currently working on a fix.
Don’t update to 06.15 if you don’t need to! Only do this if you need the unlock and you’re stuck on 05.14 or 05.15, and you’re willing to assume the above risks.
Step One
Create a folder on your desktop called Pwnage
Download RedSn0w from here and place it in the Pwnage folder. Likewise, download the latest 4.2.1 firmware from below and place it in the same folder.
4.1.0 (3G): iPhone1,2_4.1_8B117_Restore.ipsw
4.1.0 (3GS):iPhone2,1_4.1_8B117_Restore.ipsw
4.2.1 (3G): iPhone1,2_4.2.1_8C148_Restore.ipsw
4.2.1 (3GS):iPhone2,1_4.2.1_8C148a_Restore.ipsw
Extract the RedSn0w zip file into the same folder.
Step Two
Connect your iPhone to the computer and launch iTunes.
Select your iPhone from the list of devices on the left. Now hold down Shift and click the Restore button. Restore is preferred as it won't create any wasted space on your iPhone.
Navigate to the Pwnage folder on your desktop and select the 4.1 / 4.2.1 firmware ipsw. Click the Choose button to continue.
Step Three
Once iTunes has finished updating your iPhone to the desired firmware open the Pwnage folder on your desktop and launch the redsn0w application from the redsn0w folder we extracted earlier.
Step Four
Once RedSn0w opens click the Browse button
Step Five
Select the 4.2.1 firmware ipsw we placed in the Pwnage folder on our desktop then click Open.
Step Six
Once the firmware has been verified click the Next button to continue.
Step Seven
RedSn0w will now prepare the jailbreak data
Step Eight
From this window you can select the jailbreak options you would like.
Verbose boot displays detailed information on boot of your device and is generally only needed by developers and advanced users.
Make sure Cydia is selected. For this tutorial we will also select Custom boot logo and Custom recovery logo.
When you click to select each custom logo option a dialog window will appear asking you to select the image. Locate the image you would like to use then press the Open button.
*Remember the rules for boot logos are: RGB or Grayscale format with Alpha channel and dimension below 320x480.
Notice that RedSn0w can Enable multitasking, Enable homescreen wallpaper, and Enable battery percentage. If you do not need multitasking we would recommend deselecting it as it makes your iPhone 3G run very slow.
If you read the warning above and you would like to update your baseband to the 06.15 iPad version for unlock then check Install iPad Baseband. Click Yes when prompted to confirm your decision.
Click the Next button to continue
Step Nine
Please plug your iPhone into the computer and make sure its OFF then click the Next button
Step Ten
RedSn0w will now guide you through the steps to get into DFU mode. You can find more help with DFU mode here
Hold down both the Home button and the Power button for 10 seconds.
Release the Power button and continue holding the Home button until RedSn0w detects the device.
Step Eleven
RedSn0w will now downloaded the iPad baseband if needed and your iPhone will reboot
Step Twelve
RedSn0w will then begin uploading the new RAM Disk and Kernel.
Step Thirteen
Once this is complete you will be notified that RedSn0w is done. Click the Finish button. When your iPhone finishes rebooting (5 minutes or so) it will be jailbroken with Cydia on the SpringBoard.
NOTES:
If you have problems with RedSn0w on Windows Vista or Windows 7. Right click the executable and set it to run as administrator in Windows XP compatibility mode.
UNLOCK:
You can now follow this tutorial if you want to unlock your device.
*As usual a big thanks to the iPhone Dev-Team for their hard work and contribution to the iPhone community.
UNLOCK Process
These are instructions on how to unlock the iPhone 4, iPhone 3GS, and iPhone 3G for use with any GSM cellphone carrier using UltraSn0w. This will work with the iOS 4.2.1 firmware if you are on the 06.15.00 baseband.
Before you can follow these instructions you must have a jailbroken iPhone and you must be on the 04.26.08, 05.11.07, 05.12.01, 05.13.04, 06.15.00, or 01.59 baseband(modem firmware).
To find your firmware and modem firmware(baseband) versions you can follow this tutorial.
If you are on T-Mobile remember to turn off 3G before starting...
Step One
Press to launch Cydia Installer from your SpringBoard.
Step Two
Press to select the Manage tab at the bottom of the screen.
Step Three
Press to select the large Sources button
Step Four
If the ultrasn0w repo is not present press the Edit button at the top right of the screen. Otherwise, skip to Step Nine.
Step Five
Press the Add button at the top left of the screen.
Step Six
Enter repo666.ultrasn0w.com/]ultrasn0w.com as the source url and press the Add Source button.
Step Seven
Once the source has been added press the large Return to Cydia button.
Step Eight
Press the Done button at the top right of the screen.
Step Nine
Press to select repo666.ultrasn0w.com from the list of user entered sources.
Step Ten
Press to select ultrasn0w from the list of packages
Step Eleven
Press the Install button at the top right of the screen.
Step Twelve
Press the Confirm button at the top right of the screen.
Step Thirteen
After installation completes successfully press the large Restart Springboard button.
Step Fourteen
You should now be able to insert the SIM of your choice!
If there is no WIFI, still you can unlock your iPhone without WIFI, just need to download two different files to be install at your iPhone via iSprite or via Cyder2.
Download ultrasn0w_V1.2 and mobile substrate from here
And download iSprit from here
Essential download- Recboot_V1.1
Download Cyder2 from Megaupload, Rapidshare, MediaFire
Thanks
ultrasn0w
iF this tutorial help you just leave me a thanks for further.
