Here is the TRUE FIX for AT&T, Visual Voicemail and Tethering without jailbreaking. I finally tried it enough times and it works in this scenario:
Install the “pre-configured” AT&T Profile from the Ben.M site using mobile safari from your iphone.
MOST IMPORTANT PART!
DO NOT REBOOT YOUR PHONE UNTIL YOU MANUAL RESET NETWORK SETTINGS – SETTINGS -> GENERAL -> RESET -> RESET NETWORK SETTINGS.
If you reboot the phone before doing this, it seems to permanently save the wrong VMM settings. If you reset the network settings before rebooting, it reverts back to the old APN config but leaves the Tethering app installed.
I’ve tested this 10 times now and it seems to be the right steps. It did not work for me until I followed these steps exactly.
To clean this up and retry things, go into Settings / General / Profile and remove the Unsigned app. This will automatically clean the tethering support off your phone (without even rebooting).
I think this explains why a lot of people have had mixed results. Some people (like me) assume you needed to reboot the phone in order to get the Tethering working first. Other people are following step by step, but none of the steps mention the dangers of rebooting before doing the 'network reset'.
I hope this clarifies the process for anyone having trouble.
Good luck and stay safe!
