I'm sorry your unable to activate your visual voicemail. I reply on mine too and I'll be happy to get this fixed for you. Have you tried to power cycle your iPhone 6s off and on? What happens when you dial *86?
Follow us on Twitter @VZWSupport
If my response answered your question please click the ?Correct Answer? button under my response. This ensures others can benefit from our conversation. Thanks in advance for your help with this!!