Thank you for using Apple Support Communities. It's my understanding you've been unable to set up Visual Voicemail on your iPhone 7. I can see how this would be concerning, especially since it worked on your previous iPhone. You've done a great job trying to get this resolved. I've got a few more steps I'd like you to try.
Please try the steps below, testing the issue after each step:
Set up Visual Voicemail on your iPhone
- Try to call someone to check your cellular network connection.
- Make sure that you set up your voicemail. To check, dial your phone number from your iPhone.
- Call your iPhone from another phone and try to leave yourself a voicemail.
- Go to Settings > General > Reset and tap Reset Network Settings.
If the issue persists, please provide us specific details on any other steps you've done and the results.
Have a wonderful day!