After several frustrating attempts to get my T-Mobile (usa) SIM to work with a friend's iphone3G. I finally got it to work thanks to a lot of information being shared on the forum.

- Older T-mobile SIM such as 37.05A, 38.01E, OCS_2.3, OCS_2.4 works easily with yellowsn0w.
- Newer SIM (such as 267028, 525033, 39.xx) is harder to get going.

With newer SIM, there are many methods/steps people have posted in the forum. Unfortunately, they did not work for me (see image below) My T-mobile SIM has code: 267028.



The following steps described below worked for me:

1. iphone 3G restored with 2.2 fw and quickpwn'ed
2. Install SBSettings
3. Install MobileTerminal
4. Turn off 3G on phone
5. Install yellowsn0w
6. Use SBSettings to reboot phone
7. After reboot, turn ON airplane mode
8. Use mobileterminal and run "yellowsn0w -c"
9. Turn OFF airplane

Phone should begin searching .... and lock onto T-Mobile.

More tests performed after that were:

- turn off phone, turn on phone, got T-Mobile signal right away (did not have to airplane on/off)
- Remove t-mobile sim, insert subbed AT&T SIM, got AT&T signal. Turn on 3G, got 3G with AT&T.
- turn off 3G, remove subbed AT&T SIM and put back T-Mobile SIM. Got T-Mobile right away (did not have to airplane on/off)

- Put in epc.tmobile.com into data cellular network (using tzones). I can check stock, weather, youtube, and safari

- Use PDAnet 1.4 on iphone3G + my macbook, I can surf on the macbook via tzones just fine.

i'm having the same problem too. ( having the 4 dots with no carrier) . After messing around with terminal and rebooting several time i started working. However, i let the battery drain out the other day and when i turned it on same problem again. I will try your exact steps to see if it will work.

@romseadood,
You should try yellowsn0w 0.9.6 !!!
It just released and supposed to fix/improve a lot.

Or you can try my method for fun. If that does not work then go to 0.9.6. Let us know