iPhone Calls Going to Voicemail on iPhone 13

when I received calls on my iphone 13 pro, the phone rings one time and goes straight to voicemail. If the caller calls back, the call is received and I can pick up. I have had apple run hardware and software diagnostics (no hardware issues), AT&T has changed out my SIM card and even transferred to me an e-SIM, I have hard reset my iphone, with no success. I took my SIM card and tried on another iPhone and the problem continued. I tried someone else's SIM card in my iPhone with no issues, thus no issue with the iPhone. AT&T cannot solve. Anyone else have this problem?