Can't hear my phone calls. How to fix it?

"iPhone 6 can't hear caller issue is more common then you think. There are a lot of different causes for it.

I assume you took the plastic cover off? I have seen many cases where the issue of not being able to hear is because the person hasn't taken the film off the new phone.

Try to plug in some headphones and take them out, it might correct the issue.

Put some pressure to where the ear piece is connected, the connection might have gotten loose.

Check to see if blue tooth is connected. Turn it off.

Do a hard restore without the sim card being in the iphone 6.

Make sure ios is updated.

Is this iPhone unlocked? As in can you put any carrier on it? It might be for a specific carrier like AT&T or Verizon.

This iPhone 6 might not be compatible with your carrier as it is from America."

Go to voicemail. Put on speakerphone. Rapidly tap mute and speakerphone about 10 times. This worked for me when nothing else would.

There is a repair issue, that covers this. However this appears to be some kind of software thing, and possibly related to carriers. Like just previously stated. You're using an overseas carrier, where this phone was intended for an American carrier

I tried everything listed above. Nothing worked. So out of desperation I literally ran the tip of my tongue across the ear speaker several times. Then I dried it on my shirt and blew in it a couple times. Worked!!

Solved mine by sucking on the earpiece. Crazy but it was recommended on line for iPhone 4, so I tried it on my iPhone 6, and it worked. I felt rediculous, but it worked like a charm.

Try going to settings/Cellular. Then from there Enable LTE to Voice & Data. Not to sure if that will help but it cleared up the same problem I had with my 6. I live in the U.S though..