Who I have the same questioned this topic

I've read quite a few posts dating back to 2014 from Droid Turbo users experiencing the same unacceptable issue:

1) Incoming calls go straight to vmail

2) No notification of missed call

3) No notifucation of new vmail

4) - or - Vmail notification appears hours later

5) Occurs in strong signal areas - i.e. Five or Four full bars

6) Calls come through on silent. When volume and ringtone has been set.

7) When placing outgoing calls, the call is dropped upon the receiptant answering the call or their vmail coming on.

Android 5.1

On the many threads concerning this issue, VZW responded but failed to offer a viable, working solution.

Had any of VZW's "solutions" resolved this issue for the other Droid Turbo users, well, there'd be no need for me to post this.

*Note: I'm inclined to think this isn't a software issue. How could it be when so many have experienced the same issue since before 2014?