Elliesunshine Said:
"My sister’s calls go directly to voicemail any phone doesn’t ring when she calls. I receive all the other calls but when she calls it goes directly to my voicemail and I just see a missed call. she is not blocked"
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Troubleshooting Calls Going to Voicemail:
A. Start Here: If you can't Make or Receive Calls on your iPhone - Apple Support
B. "No Service":
Is "No Service" shown on the top-left corner of your screen? If so, go here to fix that: If you See No Service or Searching on your iPhone or iPad - Apple Support
C. Install a Cellular Update:
It might be prompting you for a cellular update to install. So, go here for that. Update your carrier settings manually on your iPhone or iPad - Apple Support
D. Update the iOS Using a Computer: