Called, left no message

Called and left no message (6/29/2016 6:38PM) on my work phone after hours.

Called 7/5/2016 @ 7:30 PM. Mass caller Robo voice was on the line, so I hung up.

They have been calling for weeks, sometimes multiple times a day. We never answer and they do not leave a message. Caller I.d. comes up as IMC. Finally I tried calling back to see who they are. The automated message says "You have reached the National Rifle Association" and says something about important news.

Getting calls from 423-4048. No one is there. It's annoying