Voicemail

Why do I only see 'call voicemail' button on my phone app> voicemail? I am unable to setup my voicemail on this **** phone; it is iphone 11 with Ios14.0.1.

i spent 1 hour on phone with several apple reps and they couldn't even understand me it doesnt show setup / greeting or anything.my provider confirmed that it is activated for myself. How do i get my calls to divert when i am busy? I tried calling myself from several phones it is not working at all