iPhone rings twice then goes to voicemail
Just recently, when I called my mom it would ring twice and go straight to voicemail. At first I thought she put her phone on do not distrub. But then I spoke to her and she said it wasn't. I tried calling her when she was right beside be, which worked, but then when I was away it would ring twice and go straight to voicemail but she could call me. I could call her with facetime audio but not the regular call.
[Re-Titled by Moderator]
iPhone 6 Plus, iOS 10.0.2