I Do Not Have Caller ID

We do not have caller ID. I realize this must surprise most of you because I have been getting a lot of calls lately from "you" who don't tell me who you are. I listen intently while you speak, waiting for some clue of who you are, so I don't come across as rude or that somehow you are less important to me than someone's voice that I would recognize right off the bat. I have also been getting messages that say, "Hi this is so and so, when you get this message, please call me back. I am sure you have my number on your caller ID, so I won't leave it. Oh, remember it is urgent." So, for the record, I DO NOT have caller ID. Please state who you are when you call and leave your name and number if you get my machine, if you want a call back. Thank you.