I don't have an answer to your problem, but I would recommend trying Google Voice. You can download the app and then set up online. Instead of using your regular voicemail it will forward to google voice. It will transcribe it for you, give you a list of who you have messages from (each message is one click away from a listen and you can fast forward and rewind), receive those messages via text or email, and still get a notification icon. I love it. If they don't speak clearly the transcribe doesn't do well, but you can usually get the idea of the message.