Activate unlocked Samsung Note 20 5G

I am trying to activate a samsung note 20 that is new and purchased from samsung unlocked. I am an existing customer with a note 8 currently with xfinity mobile service. I called customer service and they were no help no could give any reason other than the IMEI check did not work and could not offer any resolution.
If this can be resolved I will be looking to take my service elsewhere, but would prefer to stay with xfinity and add additional lines.