Callers can only hear me some of the time...

I have kind of a bizarre situation which seems unlike others I’ve read on this topic. I believe it has been happening for the last year or so but hard to say for sure.

I will be talking to someone on the phone and they will hear me just fine, then all of a sudden it will get really muffled/static sounding on their end. Then it will go away for a while, and come back on and off throughout the conversation. This happens with normal conversation, speaker phone, and even Bluetooth.

Things I’ve tried:

• Replacing the charging dock
• Thoroughly cleaning the speaker holes/mesh
• Resetting the phone by holding the power/home button
• Disabling “phone noise cancellation”

This has been a hard issue to troubleshoot because it’s only a problem for the person I’m talking to. Everything seems just fine on my end.

Any suggestions on where to go from here? Could this be a network or antenna issue? I have two phone lines with AT&T and when I use my other phone (an Android) it doesn’t seem to be an issue.

Thank you in advance.