So here's my solve path for the personal hotspot missing issue after upgrading to iOS6 from iOS 5.1.1. This is on a iPhone 4S. I have the 4GB data plan plus tethering (personal hotspot).
Summary of fix
- The issue wasnt the phone. It was fixed by Level 2 AT&T by messing with network/account settings. My plan didnt change to 5GB - the 4GB plan I was on is the same now its working. I didnt get a new SIM card, or a new phone. So my suggestion if you face this problem is call AT&T, and escalate the problem up through their support.
Steps Tried
- Turn phone off and on
- Reset network settings
- Restore phone using itunes back to factory defaults. Setup as a new phone.
- Restore phone and recover backup
- Do a reset on the phone (hold down top button and front button).
- Called AT&T and was transferred to Apple. Apple escalated up to a Level 2 support person. Transferred back to AT&T Level 2 support (who fixed the problem).
- Note - apple support and AT&T support apparently cannot be on the same call at the same time (some bogus rule). So they will transfer you back and forth but cant be on at the same time.
- Initially AT&T Level 1 said it was Apple problem (a punt - they couldnt work out how to fix). Apple Level 1 said it was AT&T's problem, so its important to get to Level 2 so they actually try to fix.
So like I said at the top, the key is getting AT&T to fix your account, not the phone issue. They will ask you to turn the phone off, then back on a few times, then reset network settings again. It was the network settings reset that finally fixed it for me, after they monkeyed with account settings a few times.
Good luck!