FIX (for those of you still having VVM problems)...
For those of you who don't see a "Profiles" section under "Settings > General", and for those of you who have Reset Network Settings and for those of you who have deleted the BenM.at profile file and are still having issues with VVM, odds are you DID, at some point, try tethering with the 3.0 or 3.0.1 iPhone software, which required that you install a non-AT&T IPCC file, so stop blaming your service provider and/or Apple, neither of whom is to blame for your modifying of your device software from factory installed software.
In your case, here's how to get voicemail back.
1) Disconnect your iPhone from your USB cable and quit iTunes.
2) On your Mac, browse to: 'Macintosh HD/Users/"yourhomefolder"/Library/iTunes/iPhone Carrier Support'
3) Drag all files in that folder to your Desktop. There will probably be one called "ATT_US.ipcc", which is the hacked/modified carrier support file that 3.0 used to allow tethering, which, as previously said is NOT supported by AT&T or Apple (but probably will be in the future).
NOTE - if you modified your original ATT_US.ipcc file and it is still located in that folder with a different name, like "ATT_US.ipcc.old" or something of that nature, then simply delete the one called "ATT_US.ipcc" and rename the old/original file to "ATT_US.ipcc". This will allow you to hold the "Option" key on your keyboard and click "Check for Updates" in iTunes, then manually browse to the folder listed in step 2 and choose that file... much more painless than a full factory restore. If that's your case, as it was for me, don't read any further. If you only have one file called "ATT_US.ipcc", keep reading...
4) Connect your iPhone and open iTunes.
5) Restore your iPhone to factory settings. Then re-sync whatever you want.
6) After all is well, delete the .ipcc files from your Desktop that you dragged there earlier.
Yes, this will involve re-syncing all your data - a long process. Restoring to a previous backup will not help, as that process will restore modified ATT_US.ipcc files - the correct ATT_US.ipcc file will be downloaded and copied to your computer during the restore. Hopefully you didn't delete your original, AT&T-provided .ipcc file and simply renamed it when you modified your software to enable tethering.
