Can’t hear calls on iPhone 12pro unless I put it on speaker.

Does anyone know how to fix this issue? I’ve been seeing that me and a couple of people have the same problem whenever I get an incoming or outgoing call I cannot hear anything unless I put it on speaker. But the speaker that I hold to my ear I cannot hear nothing it’s completely blank I have reset my phone messed with the sound settings did everything possible is it just a glitch or what’s going on? How can I fix it as it’s very annoying.