Motorola Droid Turbo :: Calls Going Directly To Voicemail

This past week my phone has been sending some calls straight to voicemail without even listing that someone called (no one in the recent call list). I'm trying to figure out if this is a network issue or a software/hardware issue. I've made sure that none of the callers I've missed are on the "straight to voicemail option" (I actually don't have that setting for anyone). I've checked my sound options to make sure they are turned up (and made sure it's not set to priority...I hate that new lollipop feature), and I've checked the radio signal strength. Everything seems to be in order. I tried to call the person back who left me the message and it rang several times, then gave me an error message saying that the call couldn't be completed. This happened twice and then I finally got through the third time. After that I made a call to someone else to see if it went through. It did.