Chosen Solution
I can’t hear the person I’m calling and I have my volume as high as it will go
Can you hear them on loud speaker or head phones? If you can it would point to a faulty earpiece flex assembly or the top speaker.
If you are having difficulties hearing people from your earpiece speaker could be many things. My first thought is that there might be some debris clogging up the speaker grill. Could also be a faulty top speaker flex assembly, as was mentioned already. For a more thorough list of issues I would recommend having a look at the iPhone No Sound page which has a pretty extensive list of ways to try and isolate this issue.
