Can't hear

See this, If you hear no sound or distorted sound from your iPhone, iPad, or iPod touch speaker - Apple Support

Hi jpsst,

If your call connect successfully but you can’t hear anyone on the other end or they can’t hear you - make sure

• the volume is turned up high enough
• you do NOT have “MUTE” activated
• have the person call you and verify you can hear them and they can hear you.

I have a variety of similarities to your issue. I have an iPhone 11 with iOS 14.2, and when I am using a Bluetooth earphones like airPods, powerbeats3 and Powerbeats pro, etc... this issue happens almost every time and when it does I can’t even use the iPhones speaker or the earpiece on the phone. I always have to go to Bluetooth and unpair all my Bluetooth devices, close down all open apps and the reset “Network Settings” which should reset phone but if not, turn your phone off and turn it back on after one minute. I hope this helps.