I use Phonetag and it works beautifully for what you are ultimately trying to do. However, You have to pay for it, but it's great for visual voicemail and you also get every voice mail sent as an e-mail attachment, not to mention it transcribes the voice mail to text so if you're in a meeting you can read it. It's cost $$ and you have to have sprint forward your calls. But if you really need it, (like i do) you'll need to pay for it.
Check it out if you want:
http://www.phonetag.com/