Re-activate your Visual Voicemail account. This will force the Voicemail client to send an activation message to the Server again. Once re-activated, all pending messages should be able to download again.
Option(1):
- Settings/Applications/Manage Applications/Voicemail/Clear data
- This will wipe out your old Inbox messages but your filesystem will come clean
Option(2):
Some suggested to use Visual Voicemail Compose screen and send it to the following address:
activate@vvm.sprint.com