Calls repeatedly, does not leave message

Calls almost daily, but never leaves message.

Calls cell regularly, leaves no message.  Called back from land line - it is the NRA

Called 2 days- no message

Here I am, in 2017, as I did in Oct. of 2015, reporting that this same number, is calling, and leaving no message. I NEVER pick up for unknown numbers. In leaving no message, they assure themselves that I will NEVER return their call.