My iPhone goes to voicemail when others call me

Have you accidentally enabled Do Not Disturb mode? If you see a moon in the top right of your screen (next to your battery), this means that you will not receive notifications (including incoming calls), and it will go to voicemail.

Use Do Not Disturb on your iPhone, iPad and iPod touch – Apple Support

See this thread https://discussions.apple.com/thread/251919073

I am having the same issue: when someone call's me my phone immediately goes to voicemail. I have followed the above suggested guidelines and my phone is not in the do not disturb mode. I am trying to better understand if it is a phone setting issue or a network issue. Please advise.

Thanks