Dropping Calls

For some reason my phone continuously drop calls, or I get the failed call on my screen. Also people tell me that they called me and on my end my phone didn’t ring and I have no missed calls.

I tried resetting the network, removing and replacing the SIM card, I restarted my phone, closed some of the apps that run in the background but I still having this problem. I also had it on my XR and now again on my new 12 Pro Max.

can someone please help me? What else can I do?