xfinity voicemail has never worked on my line

I have been with Xfinity mobile for 2+ years. Until this week, I had a Samsung A53; this week I transitioned to a iphone 14 pro. I have NEVER been able to get voicemail set up on this phone line; I have never had a problem with voicemail prior to switching to Xfinity mobile. I have spent hours on the phone trying to get this set up with each phone and each time I am on the phone with a representative they say they have fixed it and it will work - and surprise, it never does. I switched to the iphone and they assured me that it would work within 24 hours of activating the device, that didn't work.