I get at least 3-4 calls a day from this number.  They never leave a message and when I call back there is no answer.  
Same type of calls from 321-281-5713

Same number, same deal

couple of calls from this number - no one speaks

Seems like I've been getting more and more of these calls and I'm not sure why....  Usually I don't answer them but today I did.  After saying hello a couple of times, with no response, then heard some nose breathing into the phone, I said "are you going to speak?" - they then hung-up.