Why I can’t hear caller on my phone

Hello,

Do you use any Bluetooth speakers or headphones with your iPhone? I have seen call audto routing cause issues like this. To know for sure check where the sounds is set while on a call.

While on a call on iPhone - Apple Support

"

Adjust the audio during a call

To change the volume, press the volume buttons on the side of iPhone. Or swipe down on the call banner, then do any of the following:

• Mute: Tap the mute button.
• Put the call on hold: Touch and hold the mute button.
• Talk handsfree: Tap the audio button, then choose an audio destination."

This can happen when a Bluetooth device is on but not in your ear. Check Setting App > Accessibility > Touch > Call Audio Routing. Here you can change the default routing.

I hope this helps.