Voicemail not working on iPhone 6s. How do I fix this?

I bought a refurbished iPhone 6s and have not received any voicemails since. I just received a message today that a potential employer called and left a voicemail, but I don't see anything.

I went under "Phone" in Settings and the only option is to change Voicemail Password. I tried and I got an error that said Voicemail is unavailable. What the heck?

Nnaybe you should take your phone back to the store and get another one that will work

Try opening the phone app itself and then in the settings should be voicemail which can tap on to setup. Far as the voicemail unavaliable error try resetting the network settings to fix the issue

Contact your service provider and ask them to send you a settings update & telling them you are using the 6S.

They can send a specially formatted text message that configures the phone properly for their network; that will often fix such problems.