When tapping the Voicemail button, iPhone calls voicemail instead of displaying the Visual Voicemail list

#7 reset network settings worked for me! Thank you!

I had this issue too. After talking to Verizon and Apple and trying a few different things, what finally worked for me was going to settings>cellular>cellular data options>enable LTE>voice&data

It was set on data only, switching it to voice & data fixed the issue.

A version of this worked for my on my Verizon Iphone6. Disable voice and data over LTE. shutdown, restart, enable voice and data over LTE. shut down and restart. Worked when Verizon wanted to wipe my entire phone.