Receives call but once answered the caller goes straight to voicemail

[Android Central Question]

About a week ago this starting happening. I have a Samsung Galaxy phone with Verizon service and every time this one person calls who has an Iphone 6S and they have Sprint service, my phone rings and I go to answer the call but the call ends and the person goes straight to my voicemail. This only happens to her. We can text back and forth, I can call her but when she calls me the phone rings and I go to answer it and the call ends and she goes into my voicemail. What is the issue here?

 

[B. Diddy]

Welcome to Android Central! Open your Contacts app, select her contact entry, and tap the Menu button -- is she set to go straight to voicemail?