I have an iphone 3g running 4.0.1 with T-Mobile 4.0 MMS fix by LEI mobile installed and am attempting to tether. When i access my settings > Network > Cellular Data Network my internet tethering section is empty.
When I enter in wap.voicestream.com into the Internet tethering section, reboot and try to tether i never get the blue bar across the top of the screen notifying me that I am tethering from my device.
I think I've read every topic there is in regards to tethering but still don't see an answer to what i'm doing wrong.
I installed a mobile configuration fe from unlockit.co.az. Then I had the same blank in tethering and I reset carrier settings,rebooted and put in epc.tmobile.com. Rebooted again and mine works. Since u already have the other fix maybe just try the other steps.