Incoming calls going straight to VM

[Android Central Question]

When someone calls me, my phone don't always ring because the calls are going straight to VM and I'm not notified of texts. Also, after my new update my fitbit is showing the caller "unknown" when I have the people listed in my phone and it wasn't doing that before the update.

 

[B. Diddy]

Welcome to Android Central! Which phone? How's your cell reception when this happens? Does it only happen intermittently, or all the time?