I have a Samsung Galaxy S9 from Samsung (unlocked, no carrier software).
I had the device on AT&T until last week.
Although I setup my Verizon Voicemail, I just kept getting errors in visual voicemail ("Sorry, we're having trouble connecting. Make sure you have a good signal and try again. If you still can't connect, please contact Customer Service.")
I FIXED THIS MYSELF. I'M POSTING BECAUSE OF THE TERRIBLE ANSWERS FROM VERIZON.
Cust Service told me that "it's not possible to make visual voicemail work because the necessary software is only in the Verizon build and you don't have that".
I won't bother to explain all the reasons they're totally wrong. Instead, here's how to reset visual voicemail so you can redo setup on Verizon.
Go to device settings > apps
Clear data cache
Uninstall app updates
Update app from Galaxy store
Run through setup
Save any visual voicemail messages from old carrier before starting and all will be good.
I don't know why Verizon tech support say this is impossible.
n1njade, first and foremost, we are thrilled to have you as a member of the Verizon family. We apologize for the experience you endured and we thank you for the steps you provided to fix the Visual Voicemail issue you were having. While some features may not be available on unlocked phones, there may be workarounds. I went ahead and submitted your feedback to the correct department for internet review. While we have you here, do you have any other questions or concerns?