ZDNet – “Here’s why and how to delete them for good. If you like keeping your phone tidy by periodically deleting old messages and voicemails, you may be surprised to hear that those voicemail messages you deleted two years ago may still be on your phone…Voicemail messages are typically stored in the mobile carrier’s servers; they’re not automatically stored on the phone itself, but they can be backed up to iCloud or a computer..”