Incoming calls to my iPhone 16 Pro going to voicemail

I’ve been having an issue with my phone when clients or someone calls me. It goes straight to voicemail and they call back and it still does the same. This is an ongoing issue. I thought it was the carrier issue but it seems to be a software issue I just updated to the newest software the 18.3.1 and still having the same issue

[Re-Titled by Moderator]