phone only works on Wifi network, but not on cellular network
Hi all, For the last day or so, my iPhone is only functional (make /receive calls, apps) when it is on Wifi connection. When no Wifi available, is it as if it is on "Airplane mode". Nothing works. Have checked and reset the network settings, cellular is on and I am out of options. My service is with Xfinity Mobile. Any suggestions? Could it be the hardware?
Thanks.
needless to say, phone is fully updated. iPhone 11 Pro Max
iPhone 11, iOS 15