Getting message "Could Not Activate Cellular Data Network"

I have a new iphone se. My carrier is Page Plus which is a Verizon MVNO. Have used it for years. For two weeks my new phone worked fine then suddenly I can't access the cellular network. I get the message above.

Steps taken:

Toggled airplane settings, toggled wifi, toggled cellular = did not work

Deleted carrier profile, turned phone on and off, reinstalled carrier profile. Did not work.

Reset Network Settings. Did not work.

Called Apple and they ran diagnostics - found no phone issue, no carrier issue, no SIM restriction.

I did a full restore = in effect wiped phone and started over.

Called (again) the carrier, they ran some updates, told me to do all the things I have already done.

I order a new SIM card and installed it today. SAME PROBLEM.

WIth the WIFI off I can make phone calls, i CAN'T send texts or access the internet.

I read something about APNs but my phone doesn't seem to have the MOBILE DATA option anywhere.

I am out of ideas. I have an appointment at the Apple store but want to know if anyone has seen this persistent error.