answered on other device

For the past week when anyone calls me it goes to a voicemail that has not been set up. My voicemail is set up... I can also make calls and receive and send text. In my call log it says "answered on another device." I already shut off device sharing for calls. I also erased my iPhone and turned it back on. I reset my password for my Apple ID. I am at a total loss why this is happening. I only see my devices on my Apple ID. I have two step verification and never saw a notification of a hack. SO WHAT IS GOING ON. I have seen threads of this, but no resolution. It has been a week and I sat on the phone with apple and Virzion for 4 hours. Just have a erased phone now. Please help me. I am so upset.