Call quality issues - iPhone X

I'm having call quality issues, people I am speaking with can't hear me well or it sounds like I'm far away. I don't use voice often, but its become UNBEARABLE now when I do. Software is 12.3.1. I've tried the following and it did not solve:

• LTE (on/off)
• WiFi (on/off)
• Case (on/off)

I use ATT but I don't think its the carrier. I have 1 month left on warranty, but before I took it back, thought to see if anyone has SOLVED thier situation.

Thanks.