iPhone 7+ intermittent call silence / inability to answer incoming calls

I have an iPhone 7 Plus running 13.5.1 that has become randomly crazy. At random, my iPhone will not be able to answer incoming calls or place outgoing calls. It visually acts like it can.

For example, if I attempt to answer an incoming call, the screen will show that the call is active, the call timer runs, but my phone will still be ringing and vibrating at the same time as the call clock runs. The other party has no idea I’ve answered and it goes to voicemail for them.

Likewise if I make a call, the phone will place the call I'm trying to make, the person on the other end will see that I'm calling them, but there’s no ringing and then when the party answers I hear nothing, and people on the other end tell me they are getting an echoing sound from me.

The only remedy is to power off the phone and turn it back on; then the phone will behave normally in regard to calls. But at random, the problem will return with no rhyme or reason as to cause.

In addition, when the phone works stops working my camera functions will also become inoperable- I cannot take a photo or start a video no matter how many times I press, hold and plead with the white/red button- only a restart of the phone will resolve.

Also when these symptoms present my microphone dictate feature will also stop functioning. I can hit the button and the Mic line Displays but nothing registers and now text displays, again resolves with reboot.

i have tried wiping the phone and restoring, wiping the phone and then manually installing apps one by one and only restoring photos, messages and contacts from cloud without app data. Neither approach has worked to resolve. This issue has been present through multiple iterations of iOS 13.x