Can't hear caller and caller can't hear me

Hi,

I can't hear anyone that calls and they can't hear me. When I press the Speaker icon during the call it doesn't work.

I had to switch off vibrate because when someone calls and I press answer, it keeps vibrating on and off during the call.

If I play music, the speaker works just fine.

I can record my voice with the Voice Memos app.

If I press the volume up or down it displays Ringer and not Headphones.

Aeroplane Mode is off. Do Not Disturb is off. Bluetooth is off. Silent is off.

Do Not Disturb > Allow Calls is set to Everyone

Any ideas please?