I suggest that you follow the tech's suggestion. Also, you might want to try this: Go to Settings > Calls > look for noise suppressions, try to turn it off and see if it changes anything.

Thanks you guys for your input. The first phone was purchased in Mid July. It took me a while to realize the problem was my phone. We did the test and Verizon decided to replace the Sim Card. That didn't work so they replaced the phone........and it's acting the same way. Tech scheduled a ticket to investigate the network and I am waiting.  Just wondered if I was the only one with this problem. I have seen some others have had the same problem? Tech also suggested to shut off HD voice?

How's your network signal during those calls? Also, are you using a phone case? If you are, try to remove them. You should also check the mic if there's anything stuck in it.

I have samsung galaxy J7, but I don't have any sort of problem like this. It might be problem with your speakers.