Unavailable male type one: this is the type my friend Audrey had plans with the other night. He's a writer. Even before their first date, he sent her a list of his day's activities, ending with how, at 6pm, he was going to "dedicate a plaque to Edith Wharton, then have some Japanese food with the dean of Columbia University, and maybe a few glasses of sake, blah blah blah."

What kind of writer writes "blah blah blah"? In his case it means: "I'm too busy to write down all the mundane details, but I'm really trying to impress you with my very important schedule." That way you know you had better be grateful that he's making time for you.

Unavailable male type two: this man is unable to make plans more than five minutes in advance. I went out with one and he drove me insane. Every time I'd try to make a plan, I felt like I was asking him to set a date for the wedding. When he did commit to getting together, it was never a time or a place - just a general idea of when it might happen. For instance, he'd say: "Tuesday should work." Then on Tuesday he'd e-mail: "I have to meet someone for a drink in the early evening, then there's a birthday party in the East Village I have to go to, so I'll call when I'm done." Then, when he never called, the next day he'd say: "Well, I wasn't done till 2am and didn't want to wake you up." Very thoughtful.

Unavailable male type three is always busy. My friend Joanna is so fed up hearing how "busy" her dates are, she now refers to it as "the B-word". As in: "He used the B-word, so I dumped him." She actually runs her own business. So how much busier can he be? Some men will always be busy, even if they're unemployed.

I went out with someone who, when I asked how he was, his answer never varied: "Stressed." I'd ring to see what he was up to. "Can't talk, stressed." He was stressed in the morning, stressed in the evening. Eventually I told him to call me when he wasn't so stressed. After a month of silence, I moved on.

Unavailable male type four will give the impression he's available, but he's not. He'll agree to go away for the weekend, but will be on the phone, looking at his watch the entire time. I challenged this once and asked: "Somewhere else you'd rather be?" It taught me a lesson: don't ask a question if you're not ready for the answer.

Unavailable male type five is the "tired" man. He's closely related to the "stressed" man and "busy" man and he'd love to go away for the weekend. But he's too tired. There's a limit to how fast you can drive a car. How about a limit on how many times a day one person is allowed to say they're tired? Over five times and you're ticketed.

And here's something I've learnt. Call a busy man at 11pm and say you want to talk: he's tired. Call him at 11pm and say you're in the mood for sex and he's on his way over in a taxi before you've even finished the sentence.

Occasionally I'll get a call from a man I know who has a block on his phone number. What shows up on the caller ID is: "unavailable". It doesn't get more obvious than that, does it?