If you pay a fee, say like ten creds you can leave a message for someone. But it has to be like their cube number. Like R-10 or something. And then the person who is staying in that cube, or checks into that cube, gets it when they enter the cube.
You walk in the door and an automated voice says, "You have a message. At 12:35 WCT <Blah> left you a message that says, "I'm coming after your punk ass, narc, just you wait and see." or something like that.
I can see lots of craziness like mixed up messages because you got the cube number wrong or the person didn't pay the rent and the wrong person gets it.
Though I like NLM too.