Calls Dropping and Audio not coming through

Not certain if this is a T-Mobil or Apple issue, so I’m posting this on both.

This issue started suddenly three days ago, I can call people and it’ll ring and even answer; however, I cannot hear people speaking. They are able to hear me, but I cannot hear them. This audio issue only exists through calls. I can still play videos, music, whatever and hear it through my phone. 

Occasionally, the call will drop as well. I have updated my phone. Restarted it. And even reset my network settings to no avail, I have all my bars at the top of my phone. Any clues what the issue may be?