They call me 10 times a day on my cell phone, it is annoying I tell them to stop and I am on the do not call list. Thinking about reporting them to the FCC.

they call, i answer, they don't say anything and hangs up .  

when i don't answer, they leave a blank 3-5 second message.

they call 4 -5 times a day.  early in the morning to the night time.

They call.  I answer.  Nothing is said.  They hang up.
-OR-
They call. I don't answer.  They leave a blank 5 second message.