iPhone 13 Pro loses network settings

My iPhone 13 Pro loses ability to make phone calls or use internet data when restarted. My account is paid, the SIM card works and resetting network does not help. It lost the ability to make calls and use data last restart and randomly came back in service 3 days later. Now a new restart has started the problem again, no bars for cell service but Wi-Fi works. Resetting network has no effect.