Ah, sweet mystery of life, I know you’re calling. I’ve got caller ID.

As you probably know, caller ID tells you the name and number of whoever is trying to reach you. And with this Space Age service, all the fun of picking up the phone has gone the way of, “Hello?”

Perhaps you remember that old-fashioned greeting. It’s what you would utter — a little hopeful, a little tense — when you had no idea if it was your dream date, dad or dental receptionist calling. Today, about 40 percent of all phone subscribers get caller ID, and their ranks keep growing. This means chances are good that the person you are so eager to talk with has spent at least a nanosecond debating whether or not you are worthy of a chat.

And if you happen to be “Mom,” often the answer is — no answer. An informal survey I conducted over the Internet indicates that Mom usually goes straight to voice mail.

And mothers-in-law?

Please. As one friend put it, “My mother-in-law has an uncanny ability to call at exactly the wrong moment, like when my kids are running around killing each other.” Caller ID means never having to pick up and explain, “They love each other. Really. Those are screams of affection.”

Another friend uses her extra second of in-law prep to put on a fake cheerful voice — or flee the room. And several folks admitted they won’t pick up at all when Mom’s number beckons, simply because they know that one conversation can take up a whole evening.

Not to mention several sessions of therapy. There is a reason, notes wiseacre Joan Michelson, that it’s caller ID, as in “id.” It lets us act out all our subconscious aggressions.

Caller ID was invented circa 1988 simply because the phone company is always coming up with new ways to complicate our relationships. First it was call waiting: Do you put Friend A on hold in the hopes that a Friend B of higher quality is calling? And if Friend B turns out to be a dud, how do you get him off without actually saying, “Look, I thought you might be someone better, but — ylch.” Click.

Yep, that really enhanced our lives. Then came voice mail, which allowed us to annoy all callers with the most moronic of messages. (“We’re not home right now” — duh — “so leave a message” — double duh — “at the sound of” — gee, what could it be? The gong? The giant burp? The mariachis? No, by golly — “the beep!”)

And let’s not forget cell phones, which have us enraging absolutely everyone in earshot — which, by the way, usually does not include the person we are talking to. (“WHAT? You’re breaking up. I missed what you just — WHAT?”)

And now caller ID has become a permanent part of the landscape, thanks to the increasingly popular phone service packages that include it, no charge.

Sure, most people say they like it. OK, love it. It lets them prepare witty remarks and save valuable seconds by not having to ask, “Who is this?” And, of course, it screens out telemarketers.

But mostly, caller ID provides a life bereft of life’s little phone surprises. This is progress only if you have already purchased your aluminum siding and talked to Mom earlier in the day.

— Lenore Skenazy’s e-mail address is lskenazy@edit.nydailynews.com.