on 22-05-2013 12:20
Sometimes it happens on my Android but it's usually after I've listened to the voicemail and deleted it. The notification disappears only to reappear after a few mins thinking I've not listened to it. When I call voicemail again and have no messages it usually disappears.
on 22-05-2013 12:23
Well, it's happened a few times, maybe six times in the 2 weeks since I got the phone.
I've never received a voicemail message in that time, not a real one, but keep getting these alerts that there is voicemail but there is nothing.
on 22-05-2013 12:46
I would try to reset you network settings :
Settings > General > Reset > Reset Network Settings.
Then switch your voicemail off by dialling 1760 and switch back on by dialling 1750.
Check by dialling your mobile from another phone.
If it continues to give problems then go to the genius at your nearest Apple store.
Link is here. It may well be worth a try.