Method #1 (from Youtube's reda92)

1. Install Yellowsn0w thru Cydia, keep your Third-Party Sim in the iPhone
2. Reset Network Settings. 99% of your success rate will depend on this. (LF: you can find this in settings - general and to the bottom you'll see a "reset" menu in which you can find this)
3. Reboot your iPhone
4. Wait a little over a min.
5. Remove your SIM card and re-insert it back in
6. Wait 30 sec.
7. Turn on Airplane mode and wait 10 sec. (This is important as well)
8. Turn of Airplane mode, you should see "searching." Start smiling, as the T-Mobile carrier will start appearing.
9. Make a call!

Method #2 (from to Deli_gt at hackint0sh):

1. Recover your iPhone to the 2.2 firmware.
2. Quickpwn it with Installer and Cydia installed
3. When phone is ready, connect to your Wifi. Got to Cydia. When it opens, ignore the update for Cydia and install Mobileterminal and, after that, Sbsettings.
4. Turn off data roaming and 3G in Sbsettings!
5. Install Yellowsn0w from Installer.
6. Slide your finger from the top-left to right on the screen to get Sbsettings open
7. Press the power button in Sbsettings and from the popup restart button.
8. When the iPhone resets, wait for 20-30 seconds and open up Mobileterminal
9. Go to terminal and type:
yellowsn0w -c
yellowsn0w -q
airplane mode on
airplane mode off

If you get "open: Resource busy" just repeat the command where you got it from.
If the command "yellowsn0w -q" keeps loading for more than 20sec and your terminal looks similar to pics from Flickr: deli_gt's Photostream then move to next step.

10. Go to Settings. Turn Airplane Mode on. Wait 10 secs and it should start searching for the network. It should find the network and everything should be ok.

If not, and the iPhone still shows the four dots for the signal, repeat steps 8 and 9 but first exit mobile terminal totally by holding down the home button until it closes. If that doesn't work either try the following:

Open up the Terminal and type:
yellowsn0w -c
yellowsn0w -r
yellowsn0w -q
airplane mode on
airplane mode off

Method #3 (Mine):

1. install itunes 8 if not available and reboot pc.
2. put Sim in the phone and update to 2.2.0 firmware using iTunes and close iTunes.
3. using Quickpwn 2.2 select the same firmware to jailbreak.
4. disconnect phone from pc.
5. install sbsettings using wifi. (sbsettings is better than bosspref)
6. go to installer add source of http://i.yellowsn0w.com
7. now u see yellowsn0w 0.9.4 or search to find and install
8. bring sbsettings disable all functions except phone. (3g, bluetooth, EDGE, Wifi shoud be red and Phone will be green in color.)
9. reboot using sbsettings.
10. unlock the screen after 1 min.
11. Take out your Sim and insert it and dont touch the screen.
12. wait for exactly 5/6 min

----------------------------------------

If neither of these tricks work, again, you should definitely hit up the Yellowsn0w report and see how other people have gotten their iPhones to unlock on the various carriers. It beats searching through pages and pages of forum posts, trust us!
Give a detailed report to DEV-Team http://report.yellowsn0w.com/submit.php

AT&T 16 GB Phone now working on Rogers Canada Network, every thing works.
I used the first method.
Thanks SSKZK.

white 16GB iPhone now working on tmobile germany & vodafone germany. 1rst method used. great work!!

Dope man,just guessing hope it works on me as the past 2 people had it done

dude, the yellowsn0w -q command gives me this:
Unknown message (0xe3ff8000)
open: Resource busy
this looks like a freakin windows error......... what?
16 gig 3g, 2.2, Cosmote RO, yellowsnow 0.95

Yes Im getting the same message after entering yellowsn0w -q but no sucess after leaving things here.

Rach

Enter airplane mode and try this again.

Thanx for this info. This tutorial works for me (resetting network). 'cause im struggling for unlocking my iphone for almost an hour still cant get it. But when i read this and try to reset the network, i saw the the "magic word" SEARCHING . Until it shows up the T-mobile network.

Method #1 (from Youtube's reda92)

1. Install Yellowsn0w thru Cydia, keep your Third-Party Sim in the iPhone
2. Reset Network Settings. 99% of your success rate will depend on this. (LF: you can find this in settings - general and to the bottom you'll see a "reset" menu in which you can find this)
3. Reboot your iPhone
4. Wait a little over a min.
5. Remove your SIM card and re-insert it back in
6. Wait 30 sec.
7. Turn on Airplane mode and wait 10 sec. (This is important as well)
8. Turn of Airplane mode, you should see "searching." Start smiling, as the T-Mobile carrier will start appearing.
9. Make a call!

THANKS DEV TEAM

the error message is still there even if I try -q with airplane mode on

Try turning airplane mode on and airplane mode off straight away. Hopefully you should see searching.