Voicemail problems I upgraded to version 7 and I am getting a voicemail error "failed to fetch Your voicemail from the server"

Excuse this very basic answer first, but it's the simplest fix. Have you checked your Cellular Data feature is still turned on? Go to the Settings app. Select Cellular. Slide the circle to the right.

If it's not this simple fix, some people have had luck with the Reset Network Settings option. Go to your Settings app. Select General > Reset > Reset Network Settings. Lots of people have perfect luck with this, but others have found that the problem recurs.

Another option is to call your carrier. You do not mention who your carrier is, but Voicemail issues are often a carrier issue and not a phone issue. Some people have had luck by calling their carrier, or going on their carrier's website and resetting their voicemail passwords.

Good luck to you!