As stated, there is no voicemail application anywhere on the device. I have tried installing several but none of the Samsung ones I have found are supported.
Verizon is the service provider but because this is an unlocked version their Visual Voicemail is not supported. They have told me I need to get the app from Samsung. I have tried copying the version from the old Verizon S8 which does install but then says not supported when attempting to run it. I have tried copying the Samsung version from my S10E but it will not install. I have tried to install from a link I found here on the board for version 12.0 but it will not install says it is not supported on the S20.