Not a working number
I have recently started getting a problem with my att phone voice call, whenever someone calls me and if I am unable to pick up call or just disconnect. A call gives the message as "Not a working number" rather than it diverting it to my voicemail. I have called three times after spending hours in waits to customer service and all they are unable to address the issue. Please help me fix this issue.
things tried already: 1. reset voicemail box twice 2. restart phone 3. reset network settings. 4. my phone is uptodate as per current version of the software.