After more than 15 years covering everything Apple, it’s with a heavy heart we announce that we will no longer be publishing new content on iMore and the iMore forums will be closing as of November 1st, 2024.
Did you set up your voicemail already? If not, you box isn't active yet. If so did someone leave you a message yet? You go to the phone.app and the button on the right is the voicemail button.
As far as myVerizon, you need to install from the app store.