USUALLY WHEN THEY call, they begin with a formal introduction, telling you their name and the namen of their organization and then, because they have learned the hard way that they must not stop, they plunge on, telling you why their cause is so good and why you have to write about it. More often than not the caller is a woman and more often than not the conversation is kept general. They will talk of "the people" who need help, or "those people" or "our people" - that sort of thing. It is never "I" or "me" or "us." and they never say, as the lady finally did the other day, that they are talking about themselves and that life has suddenly become very perilous. She blamed it on being a woman - an aging woman.

Normally, I start to doodle on my pad when I get these calls. There comes a time when you get tired of causes - tired of yet another oppressed, deprived group. There seem to be so many lately that you want to say after a while that, yes, life is tough, but really I don't think that Maine should be returned to the Indians and I don't think that being nonwhite is requisite enough for admission to law shcool - that sort of thing. But the groups that really get you are the groups you didn't think had a case at all. Women are probably the best example of that, and it took some time, frankly, to see things from their point of view - understand that the most protested and pampered group among us could also be among the most exploited.

So here was this lady on the phone with a new cause - aging women. Not old women or old ladies or women wasting away on the shaded porches of nursing homes, but aging women, whoever they might be, and how the world was picking on them. What they needed, she said, were laws - laws that guaranteed them a piece of their husband's pensions in the event of divorce. That was just for starters. She ocntinued and I recalled some of the aging women I had seen around. I saw them sitting on park benches, wearing the minks of yesteryear, calling each other darling and dearie and I didn't feel in the least bit sorry for them. But then something the lady said jarred me.

I had been to a party and there had been a lady there named Kay McGrath who had once run for the City Council from the wealthiest part of town. I had a bone to pick with her and it had to do with the fact that her area is always asking for money. She conter-attacked. She told me not to be deceived by the figures. There were people in her area who were very poor. Mostly, she said, they are the old and what she asked me to do, more or less, was close my eyes and recall those times in the Safeway or the Giant when you see an old lady come slowly down the aisle, pick up an item like it was made of fine glass, find the price and then put it down because it has gone up a penny or two.

But for me the old lady who came to mind was the one who once lived down the hall. She was rich and her apartment was huge and every year, or so we were told, she bought herself a new mink. Then she would sit in the mink and rock herself in a chair and fall asleep smoking, burning holes in the fur. One day someone came and tried to collect on a bill and then someone else tried to collect and then it was discovered that the old lady had no money at all. So they took her away to some home and then someone came and put red tags on the furniture. They sold it all. She had some magnificient stuff.

Anyway, that was something like what the lady on the phone was talking about and so I asked her about the old ladies - the old ladies on shrinking budgets and fading hopes. Could she find me one? And this is what she said. She said she was one of them. She told me that she had been affluent once, a housewife once, the wife of a foreign service officer who had played by the rules. She had a master's degree and a head on her shoulders, but she had given up her career to set a table and mix drinks and now in her 58th year, they were divorced. She got some things and he got some things, but one of the things she did not get was a piece of his annuity. The law here says she does not have to get it and her husband would not let her have it.

Now her voice was no longer matter-of-fact and official sounding. Instead, there were pauses and what sounded like gulps of air. She told me how much she lives on and while it is not exactly poverty, it is also not the affluence she had come to know - not the nice and secure life she had every reason to expect. And then she got to the worst part. There was no margin for sickness - no insurance. One illness, one slip on the cold winter's ice and she really would be poor.

"I was a depression child," she said, "and now I've come full cycle - not poverty, actually . . . " She broke off the sentence there and then she said. "The thing is, I'm terribly insecure. Poverty, I see that ahead of me."

By now the pauses were longer and the breaths deeper and so now it was I who wanted to get this thing back on a business-like footing. So I asked for her phone number and then I repeated her name to make sure I had it right and sometime before I hung up I called her Mrs. Her voice stiffened. "Ms.," she said.

She's earned it the hard way.