Separating text messages from "visual voicemail" in At&t HTC A9?

[AC Question]

I want to use two separate apps, one for voicemail, and another for text messages. The "Messages" and "Visual VM" app appears to be one-in-the-same. The primary complaint is that the app always seems to open up into the "All Messages" window that jumbles VM & TM all together. I'd like it to open into the VM column if I use the VM icon (which it does, kinda) or open into the SMS/Text column if the "messages" icon is used, which it does not do if the VM was opened previously. How do I get it do display what I ask for and only what I ask for?