Thumbs down Note 3 Missing Calls/Delayed Texts

I've searched around but i can't seem to find a solution. My note 3 is missing calls, and not notifying me. When someone calls it rings on their end but my note 3 doesn't seem to be getting the signal, but i get their voice-mail a few seconds later. This is just ridiculous, how can a $700 phone fail to complete the most basic function of a phone.
Now, let me just say that I have excellent coverage in my area, and my previous phone did not have this issue, i'v also tried factory resetting and even exchanged the phone! if anyone else is having this issue, please share.

Again, this is my second note 3! i exchanged the first one for the same issue, but its happening again after the exchange! This is really frustrating.