Problems with calls

[Anton1]

I have a problem. Sometimes when I call someone, I don't hear them, but they hear me. It's not about the device, because it's new and in perfect condition. What is the problem? Is there any way to stop this?

P.S. Everything goes back to normal when I call back.

[pgn]

Have you got a cover on your phone, that perhaps is blocking the tiny speaker opening for your earpiece, @Anton1?  Is it the same hands-free?

Have you checked your cellular signal is good? This app can help with some of the work: https://www.o2.co.uk/apps/my-network