My telephone exists for my convenience, not yours.
I've always found telephones to be awfully obtrusive. As did Alexander Graham Bell, the man who invented the silly thing. He hired a secretary to answer his, and then planted them both outside his office so that he could work without interruption. Ring, ring, ring, drop what you're doing and answer me, whatever it is, it just can't be as important as answering me, answer me, answer me...
If your call is business-related and the current time in my time zone does not fall within standard business hours (09:00-12:00 and 13:00-17:00, Monday through Friday), then you might as well hang up right now. I will not pick up, I will not listen to your message, I will not return your call.
(Thoughtful business callers will realize that since I'm probably not at home during standard business hours, calls made during those hours are of little use. Good. You're catching on.)
Don't waste time telling me the current time. My answering machine timestamps messages automatically, as most machines do these days. Even if it didn't, the time of your call is irrelevant unless it is somehow pertinent to the message itself. Do, however, remember to...
Identify yourself. You may know who you are, but that doesn't mean I will. The words Call me spoken rapidly into my answering machine may not provide sufficient information for me to even consider doing so. Which reminds me...
Don't leave a message whose information content can be summarized as Call me. You're the one who wanted to say something... Say it!
My telephone exists for my convenience, not yours.
I said that already? Oh, well, please leave a message after the beep...