It appears that T-Mobile hasn’t blocked Internet Tethering on the iPhone 4 that runs iOS 4. We tested just now with a T-Mobile SIM card (chopped and converted to a micro SIM) and successfully enabled internet tethering over Bluetooth and USB. This is on a SIM free 16GB iPhone 4.
To get the menu option to appear in the network settings menu, you need to go to the Cellular Data Network settings menu and enter the APN, Username and Password. For T-Mobile it’s the following settings…
Internet Tethering:
APN: general.t-mobile.co.uk
Username: t-mobile
Password: tm
Once entered the Internet Tethering option appears on the menu before and when enabled you can switch Tethering on. It tells you if Bluetooth is disabled and gives you the option of USB Tether if you cannot use Bluetooth. When active a blue bar pulses just below the status bar in blue informing you that tethering is active. After testing over 3G, it works very well!
From my understanding it appears that T-Mobile do not impose any restriction on Tethering and if you have a price plan with data, you can Tether your phone to your computer.
Update: In the TOS is forbids using your phone as a modem. However, they don’t block tethering on the iPhone unlike other networks. We’ll need to wait for their iPhone 4 plans to come out and see if tethering is bundled in with that.
The plan on the converted micro SIM we used is a Combi 25 with an Internet Plus added which was simply added about 3 years ago when I first got the SIM card so that my Tytn II could have “unlimited” internet.
T-Mobile in the UK hasn’t revealed prices yet for the iPhone 4, so we do not know if this is just an oversight or if T-Mob are happy for users to use tethering on their regular plan.
This no longer works, does anyone have a bypass??
Not yet. Seems to have been locked sometime in Jan or Feb. Only option seems to be to pay for it.