*skip to step #4 if you already unlocked your iphone.

1. Upgrade to OS 3.0 using this custom FW, already jailbreaked w/ Cydia and ICY. Download iphone OS 3.0 FW.
2. Use Cydia or Icy, add source repo666.ultrasn0w.com
3. Install Ultrasn0w
4. Download the http://www.unlockit.co.nz/IPCC/t-mobile.ipcc
5. Make sure itunes is not running
6. if you are on:
(Mac) – open a terminal and type in..
defaults write com.apple.iTunes carrier-testing -bool TRUE
(Windows) – open up a command shell and type in:
“%ProgramFiles%iTunesiTunes.exe” /setPrefInt carrier-testing 1
This should now allow you to update your iPhones IPCC file in itunes 8.2 via Shift-Update (Windows) or Command-Update (Macintosh) in itunes. Choose the IPCC File and install
7. Use iPhone browser and go here to Enable Tethering and MMS Unlockit.co.nz. It does it automatically, and took 5 seconds to work. (Continue -> Custom -> Carrier: US T-mobile (1st one) -> Change to YES for MMS option -> press Create profile button)
8. on iphone, go to Settings -> General -> Cellular Data Network:
Cellular Data:
apn: internet2.voicestream.com
username:
password:

Visual Voicemail:
apn: internet2.voicestream.com
username:
password:

MMS:
apn: wap.voicestream.com
username:
password:
MMSC: 216.155.174.84/servlets/mms
MMS Proxy 216.155.165.50:8080
MMS Max Message Size:
MMS UA Prof URL:

(fyi: setting wap.voicestream.com for Cellular Data screwed up my internet connection, it tells me that i need to upgrade my internet service. stupid! i’m on $9.99/mth plan for 50mb & 200 sms/mms. And t-mobile doesn’t have visual voicemail, so Visual Voicemail setting doesn’t matter)
9. Reboot iphone, and you should see the camera icon when you’re in SMS application -> Create new SMS

10. To use Tethering, on iphone go in Setting -> General -> Network -> Turn on “Internet Tethering”

11. Turn on Bluetooth and pair with your laptop if you want to connect via bluetooth.

It works for me – sending and receiving. Very good quality. I tried sending and receiving to Sprint & Verizon phones. AT&T doesn’t work, so didn’t try yet. Let me know if you’ve try on the other service providers. Have fun and good luck.